Note: Descriptions are shown in the official language in which they were submitted.
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
VERGENCE WEIGHTING SYSTEMS AND METHODS FOR TREATMENT
OF PRESBYOPIA AND OTHER VISION CONDITIONS
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit of and priority to U.S. Provisional
Patent Application
62/101,436 filed January 9, 2015, the contents of which are incorporated
herein by reference in its
entirety. Full Paris Convention priority is hereby expressly reserved.
[0002] This application is related to U.S. Patent Application No. 13/732,124
filed December 31,
2012, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0003] Embodiments of the present invention relate generally to goal functions
or visual
function diagnostic metrics, and particular embodiments provide methods,
devices, and systems
for mitigating or treating vision conditions such as presbyopia, often by
determining a treatment
shape based on selected weighting values for certain viewing distances.
[0004] Presbyopia normally develops as a person ages, and is associated with a
natural
progressive loss of accommodation, sometimes referred to as "old sight." The
presbyopic eye
often loses the ability to rapidly and easily refocus on objects at varying
distances. There may also
be a loss in the ability to focus on objects at near distances. Although the
condition progresses
over the lifetime of an individual, the effects of presbyopia usually become
noticeable after the age
of 45 years. By the age of 65 years, the crystalline lens has often lost
almost all elastic properties
and has only limited ability to change shape. Residual accommodation refers to
the amount of
accommodation that remains in the eye. A lower degree of residual
accommodation contributes to
more severe presbyopia, whereas a higher amount of residual accommodation
correlates with less
severe presbyopia.
[0005] Known methods and devices for treating presbyopia seek to provide
vision approaching
that of an emmetropic eye. In an emmetropic eye, both distant objects and near
objects can be
seen due to the accommodation properties of the eye. To address the vision
problems associated
with presbyopia, reading glasses have traditionally been used by individuals
to add plus power
diopter to the eye, thus allowing the eye to focus on near objects and
maintain a clear image. This
approach is similar to that of treating hyperopia, or farsightedness.
[0006] Presbyopia has also been treated with bi-focal eyeglasses, where one
portion of the lens
is corrected for distance vision, and another portion of the lens is corrected
for near vision. When
1
3328654 vl.Active
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
peering down through the bifocals, the individual looks through the portion of
the lens corrected
for near vision. When viewing distant objects, the individual looks higher,
through the portion of
the bi-focals corrected for distance vision. Thus with little or no
accommodation, the individual
can see both far and near objects.
[0007] Contact lenses and intra-ocular lenses (IOLs) have also been used to
treat presbyopia.
One approach is to provide the individual with monovision, where one eye
(usually the primary
eye) is corrected for distance-vision, while the other eye is corrected for
near-vision.
Unfortunately, with monovision the individual may not clearly see objects that
are intermediately
positioned because the object is out-of-focus for both eyes. Also, an
individual may have trouble
seeing with only one eye, or may be unable to tolerate an imbalance between
their eyes. In
addition to monovision, other approaches include bilateral correction with
either bi-focal or multi-
focal lenses. In the case of bi-focal lenses, the lens is made so that both a
distant point and a near
point can be focused. In the multi-focal case, there exist many focal points
between near targets
and far targets.
[0008] Surgical treatments have also been proposed for presbyopia. Anterior
sclerostomy
involves a surgical incision into the sclera that enlarges the ciliary space
and facilitates movement
of the lens. Also, scleral expansion bands (SEBs) have been suggested for
increasing the ciliary
space. Problems remain with such techniques, however, such as inconsistent and
unpredictable
outcomes.
[0009] In the field of refractive surgery, certain ablation profiles have been
suggested to treat the
condition, often with the goal of increasing the range of focus of the eye, as
opposed to restoring
accommodation in the patient's eye. Many of these ablation profiles can
provide a single excellent
focus of the eye, yet they do not provide an increased depth of focus such
that optimal distance
acuity, optimal near acuity, and acceptable intermediate acuity occur
simultaneously. Shapes have
been proposed for providing enhanced distance and near vision, yet current
approaches do not
provide ideal results for all patients.
[0010] To evaluate the effectiveness of a refractive correction, such as with
a spectacle lens,
contact lens, intra-ocular lens, or laser refractive surgery procedure, it may
be desirable to consider
a merit function, or gauge of optical quality, that can determine such
effectiveness. Gauges of
optical quality are discussed in copending patent application numbers
60/431,634, filed December
6, 2002, 60/468,303, filed May 5, 2003, and 10/738,358 filed December 5, 2003,
the disclosures of
which are hereby incorporated by reference. Merit functions may be used in
evaluating post-
corrective measurements, and in predicting the effect or outcome of a proposed
corrective
2
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
procedure. While the merit function may be objective, it may also desirable
that the merit function
have a good correlation with subjective test results such as visual acuity,
contrast acuity, and the
like. The following optical metrics can be or have been used as possible
optical metrics or merit
functions: high order (HO) root mean square (RMS) error; Strehl ratio;
modulation transfer
function (MTF) at specific spatial frequencies; volume under MTF surface up to
a certain spatial
frequency; compound MTF; encircled energy; and wavefront refractions. Other
goal functions or
visual function diagnostic metrics are available for characterizing lenses and
other optical systems,
including visual acuity such as logMAR, refractive error such as sphere and
cylinder, and contrast
sensitivity (CS). However, many of the currently used goal functions are
difficult and
cumbersome to implement with current clinical methods, and are insufficient in
utilizing currently
available clinical data and in providing guidance to the administration and
diagnosis of reported
visual difficulties.
[0011] In light of the above, it would be desirable to have improved methods,
devices, and
systems for treatment and/or mitigation of optical defects, based on improved
goal functions such
as a compound modulation transfer function. The goal functions should be
easily implemented
with existing clinical data, and with clinical data that is currently being
generated by present
measurement techniques. Optionally, it would be desirable to have improved
methods, devices,
and systems for treatment and/or mitigation of presbyopia and other optical
defects. It may be
desirable to provide improved prescriptions in the form of practical
customized or optimized
prescription shapes for treating or mitigating vision conditions such as
presbyopia in a particular
patient.
BRIEF SUMMARY OF THE INVENTION
[0012] Embodiments of the present invention encompass systems and methods for
determining
optimizer values that involve factoring in the variation of the optical metric
over a range of testing
points, or vergence, to account for the distance vision, intermediate vision,
and near vision. In
some cases, various weighting protocols can be implemented to that assign
different weighting
values for different viewing distances. Such techniques can be used in various
types of treatment
modalities, including without limitation refractive surgery, contact lenses,
intraocular lenses,
spectacle lenses, and other vision correction approaches such as inlays,
conductive keratoplasty,
and the like.
[0013] In some cases, systems or methods as disclosed herein can be used in
conjunction with
therapeutic protocols that involve providing a patient with a presbyopia
treatment if the residual
accommodation of the eye exceeds the threshold residual accommodation
calculated for the eye,
3
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
for example as discussed in U.S. Patent No. 7,762,668, the content of which is
incorporated herein
by reference. In some cases, systems or methods as disclosed herein can be
used in conjunction
with multifocal therapeutic protocols for presbyopia. In some cases, systems
or methods as
disclosed herein can be used for treating pre-presbyopic patients. In some
cases, the vergence
weighting protocols disclosed herein can be used on conjunction with vision
treatment approaches
such as those described in U.S. Patent Application No. 10/872,331 filed June
17, 2004, U.S. Patent
Application No. 11/156257 filed June 17, 2005, U.S. Patent Application No.
12/126,185 filed May
23, 2008, and U.S. Provisional Patent Application No. 62/035,874 filed August
11, 2014, the
contents of each of which are incorporated herein by reference.
[0014] Embodiments of the present invention provide devices, systems, and
methods that use
improved goal functions for mitigating or treating vision conditions in a
patient. The goal function
can reflect optical quality throughout a vergence range. The goal function may
also comprise a
ratio of an optical parameter of the eye with a diffraction theory parameter.
Relatedly, the goal
function may also comprise at least one parameter selected from the group
consisting of Strehl
Ratio (SR), modulation transfer function (MTF), point spread function (PSF),
encircled energy
(EE), MTF volume or volume under MTF surface (MTFV), compound modulation
transfer
function (CMTF), and contrast sensitivity (CS).
[0015] In some instances, these techniques can be carried out in conjunction
with treatments
provided by any of a variety of laser devices, including without limitation
the WaveScan System
and the STAR 540 Excimer Laser System both by Abbott Medical Optics Inc., the
WaveLight
Allegretto Wave Eye-Q laser, the Schwind Amaris TM lasers, the 217P excimer
workstation by
Technolas PerfectVision GmbH, the Mel 8OTM laser by Carl Zeiss Meditec, Inc.,
and the like. In
some cases, embodiments provide techniques for using laser basis data during
refractive surgery
treatment procedures which can be implemented in such laser devices.
[0016] In one aspect, embodiments of the present invention encompass systems
and methods for
treating a vision condition of an eye in a particular patient. Exemplary
methods may include
receiving a vision requirements specification selected for the particular
patient, where the vision
requirements specification includes a first weighting value for a first
viewing distance within a
vergence range and a second weighting value for a second viewing distance
within the vergence
range, and determining an optical surface shape for the particular patient.
The optical surface
shape can be based on the vision requirements specification and an optical
metric. Methods can
also include treating the vision condition of the eye of the particular
patient by providing a
treatment to the patient, where the treatment includes or is based on a shape
that corresponds to the
4
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
optical surface shape. In some cases, the first viewing distance is a near
vision viewing distance,
an intermediate vision viewing distance, or a distance (far) vision viewing
distance. In some cases,
the second viewing distance is a near vision viewing distance, an intermediate
vision viewing
distance, or a distance (far) vision viewing distance. In some cases, the
first weighting value is
different from the second weighting value and the first viewing distance is
different from the
second viewing distance. In some cases, the first weighting value is greater
than the second
weighting value. In some cases, the first weighting value is less than the
second weighting value.
In some cases, the first viewing distance is greater than the second viewing
distance. In some
cases, the first viewing distance is less than the second viewing distance.
According to some
embodiments, the optical metric is a composite optical metric. In some cases,
the optical metric
includes a compound modulation transfer function (CMTF) parameter having a
combination of
modulation transfer functions (MTF's) at a plurality of distinct frequencies.
In some cases, the
first and second weighting values are members of a weighting value
distribution that is linear
across a vergence range that includes the first and second viewing distances.
In some cases, the
first and second weighting values are members of a weighting value
distribution that is non-linear
across a vergence range that includes the first and second viewing distances.
According to some
embodiments, a step of treating the vision condition of the eye of the
particular patient can include
a procedure such as ablating a cornea of the eye of the particular patient to
provide a corneal
surface shape that corresponds to the optical surface shape, providing the
particular patient with a
contact lens or a spectacle lens having a shape that corresponds to the
optical surface shape, or
providing the particular patient with an intra-ocular lens having a shape that
corresponds to the
optical surface shape.
[0017] In another aspect, embodiments of the present invention encompass
systems and methods
for generating an optical surface shape for use in treating a vision condition
of an eye in a
particular patient. Exemplary methods can include receiving a vision
requirements specification
selected for the particular patient, where the vision requirements
specification includes a first
weighting value for a first viewing distance within a vergence range and a
second weighting value
for a second viewing distance within the vergence range. Further, methods can
include generating
the optical surface shape for the particular patient, where the optical
surface shape is based on the
vision requirements specification and an optical metric. In some cases,
methods may also include
determining a procedure for treating the vision condition of the eye of the
particular patient based
on the optical surface shape. In some cases, the procedure can include
ablating a corneal surface
of the eye of the particular patient to provide a corneal surface shape that
corresponds to the
optical surface shape, providing the particular patient with a contact lens or
a spectacle lens having
5
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
a shape that corresponds to the optical surface shape, or providing the
particular patient with an
intra-ocular lens having a shape that corresponds to the optical surface
shape. In some cases, the
first viewing distance is a near vision viewing distance, an intermediate
vision viewing distance, or
a distance vision viewing distance. In some cases, the second viewing distance
is a near vision
viewing distance, an intermediate vision viewing distance, or a distance
vision viewing distance.
In some cases, the first weighting value is different from the second
weighting value and the first
viewing distance is different from the second viewing distance. In some cases,
the first weighting
value is greater than the second weighting value. In some cases, the first
weighting value is less
than the second weighting value. In some cases, the first viewing distance is
greater than the
second viewing distance. In some cases, the first viewing distance is less
than the second viewing
distance. According to some embodiments, the optical metric is a composite
optical metric. In
some cases, the optical metric includes a compound modulation transfer
function (CMTF)
parameter having a combination of modulation transfer functions (MTF's) at a
plurality of distinct
frequencies. In some cases, the first and second weighting values are members
of a weighting
value distribution that is linear across a vergence range that includes the
first and second viewing
distances. In some cases, the first and second weighting values are members of
a weighting value
distribution that is non-linear across a vergence range that includes the
first and second viewing
distances.
[0018] In still another aspect, embodiments of the present invention encompass
systems and
methods for establishing an optical surface shape for use in treating a vision
condition of an eye in
a particular patient. Exemplary systems can include nn input that receives a
vision requirements
specification selected for the particular patient, where the vision
requirements specification
includes a first weighting value for a first viewing distance within a
vergence range and a second
weighting value for a second viewing distance within the vergence range.
Systems can also
include a data processing module having a processor and a tangible non-
transitory computer
readable medium, where the computer readable medium is programmed with a
computer
application that, when executed by the processor, causes the processor to
establish the optical
surface shape for the eye of the particular patient. The optical surface shape
can be based on the
vision requirements specification received by the input and an optical metric.
In some cases, the
computer application, when executed by the processor, causes the processor to
determine a
protocol for treating the vision condition of the eye of the particular
patient based on the optical
surface shape. In some cases, the protocol includes a photodisruption
procedure for a corneal
tissue of the eye of the particular patient, where the photodisruption
procedure is configured to
provide a corneal surface shape that corresponds to the optical surface shape.
In some cases, the
6
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
protocol includes a contact lens or a spectacle lens procedure for the eye of
the particular patient,
where the contact lens or spectacle lens procedure involves a lens having a
shape that corresponds
to the optical surface shape. In some cases, the protocol includes an intra-
ocular lens procedure for
the eye of the particular patient, where the intra-ocular lens procedure
involves a lens having a
shape that corresponds to the optical surface shape. In some cases, the first
viewing distance is a
near vision viewing distance, an intermediate vision viewing distance, or a
distance vision viewing
distance. In some cases, the second viewing distance is a near vision viewing
distance, an
intermediate vision viewing distance, or a distance vision viewing distance.
In some cases, the
first weighting value is different from the second weighting value and the
first viewing distance is
different from the second viewing distance. In some cases, the first weighting
value is greater than
the second weighting value. In some cases, the first weighting value is less
than the second
weighting value. In some cases, the first viewing distance is greater than the
second viewing
distance. In some cases, the first viewing distance is less than the second
viewing distance.
According to some embodiments, the optical metric is a composite optical
metric. In some cases,
the optical metric includes a compound modulation transfer function (CMTF)
parameter having a
combination of modulation transfer functions (MTF's) at a plurality of
distinct frequencies. In
some cases, the first and second weighting values are members of a weighting
value distribution
that is linear across a vergence range that includes the first and second
viewing distances. In some
cases, the first and second weighting values are members of a weighting value
distribution that is
non-linear across a vergence range that includes the first and second viewing
distances.
[0019] In yet another aspect, embodiments of the present invention encompass
computer
program products for generating an optical surface shape for use in treating a
vision condition of
an eye in a particular patient. In some cases, the computer program product is
embodied on a
tangible non-transitory computer readable medium and includes code for
accessing a vision
requirements specification selected for the particular patient. The vision
requirements
specification can include a first weighting value for a first viewing distance
within a vergence
range and a second weighting value for a second viewing distance within the
vergence range. The
computer program product can also include code for generating the optical
surface shape for the
particular patient, where the optical surface shape is based on the vision
requirements specification
and an optical metric. In some cases, a computer program product can also
include code for
determining a protocol for treating the vision condition of the eye of the
particular patient based on
the optical surface shape. According to some embodiments the protocol can
include a
photodisruption procedure for a corneal tissue of the eye of the particular
patient. The
photodisruption procedure can be configured to provide a corneal surface shape
that corresponds
7
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
to the optical surface shape. According to some embodiments the protocol can
include a contact
lens or a spectacle lens procedure for the eye of the particular patient. A
contact lens or spectacle
lens procedure can involve a lens having a shape that corresponds to the
optical surface shape.
According to some embodiments the protocol can include an intra-ocular lens
procedure for the
eye of the particular patient. An intra-ocular lens procedure can involve a
lens having a shape that
corresponds to the optical surface shape. In some cases, the first viewing
distance is a near vision
viewing distance, an intermediate vision viewing distance, or a distance
vision viewing distance.
In some cases, the second viewing distance is a near vision viewing distance,
an intermediate
vision viewing distance, or a distance vision viewing distance. In some cases,
the first weighting
value is different from the second weighting value and the first viewing
distance is different from
the second viewing distance. In some cases, the first weighting value is
greater than the second
weighting value. In some cases, the first weighting value is less than the
second weighting value.
In some cases, the first viewing distance is greater than the second viewing
distance. In some
cases, the first viewing distance is less than the second viewing distance. In
some cases, the
optical metric is a composite optical metric. In some cases, the optical
metric includes a
compound modulation transfer function (CMTF) parameter having a combination of
modulation
transfer functions (MTF's) at a plurality of distinct frequencies. In some
cases, the first and
second weighting values are members of a weighting value distribution that is
linear across a
vergence range that includes the first and second viewing distances. In some
cases, the first and
second weighting values are members of a weighting value distribution that is
non-linear across a
vergence range that includes the first and second viewing distances.
[0020] For a fuller understanding of the nature and advantages of the present
invention,
reference should be had to the ensuing detailed description taken in
conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Fig. 1 illustrates a laser ablation system according to an embodiment
of the present
invention.
[0022] Fig. 2 illustrates a simplified computer system according to an
embodiment of the present
invention.
[0023] Fig. 3 illustrates a wavefront measurement system according to an
embodiment of the
present invention.
8
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0024] Fig. 3A illustrates another wavefront measurement system according to
an embodiment
of the present invention.
[0025] Fig. 4A illustrates an example of the compound MTF (upper panel) versus
its
corresponding individual MTF curves at 15, 30, and 60 cycles per degree (lower
panel).
[0026] Fig. 4B illustrate an example of the compound MTF (upper panel) versus
its
corresponding individual MTF curves at 10, 20, and 30 cycles per degree (lower
panel).
[0027] Fig. 5 is a flow chart illustrating exemplary method steps for
optimizing an optical
prescription that treats or corrects a vision condition.
[0028] Fig. 6 illustrates a data flow process for shape optimization for
correction or treatment of
a vision condition.
[0029] Fig. 7 illustrates a comparison of Direction Set method and Downhill
Simplex method.
[0030] Figs. 8A and 8B illustrate alternative prescriptions optimized for an
eye of a particular
patient, and their characteristics.
[0031] Fig. 8C illustrates a comparison of optimizer values using even-term
polynomials and all
power term polynomials for pupil sizes of 4mm, 5mm, and 6mm.
[0032] Figs. 9A-D, show alternative presbyopia-mitigating prescriptions
optimized for an eye of
a particular patient.
[0033] Fig. 10 illustrates effects of random noise on prescriptions optimized
for an eye of a
particular patient.
[0034] Figs. 11A-C compare optimized prescriptions to alternative treatments
for differing pupil
sizes.
[0035] Figs. 12A-C compare optimized prescriptions to alternative treatments
for a range of
viewing distances.
[0036] Fig. 13 illustrates simulated viewing charts viewed at differing
distances to compare
optimized prescriptions to alternative treatments.
[0037] Figs. 14-16 illustrate graphical interface computer screen displays for
a prescription
optimizer and system.
[0038] Figs. 17 and 18 illustrate pupil sizes and changes at differing viewing
conditions for a
particular patient.
9
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0039] Fig. 19 graphically illustrates optimizer values for differing levels
of residual
accommodation.
[0040] Fig. 20 illustrates effects of pupil change and residual accommodation
on optimized
prescriptions for a particular patient.
[0041] Figs. 21A-C illustrate effects of pupil change and residual
accommodation on optimized
prescriptions for a particular patient.
[0042] Figs. 22-24 compare optical properties and results of eyes corrected
with an optimized
prescription to alternative treatments.
[0043] Fig. 25 schematically illustrates a system for determining a
prescription for a particular
patient and delivering that treatment using laser refractive surgery.
[0044] Fig. 26A illustrates a relationship between accommodation and pupil
size when healthy
eyes adjust to differing viewing distances.
[0045] Fig. 26B illustrates one exemplary relationship between effective power
of an eye and
pupil size for a patient, as can be provided from the presbyopia prescriptions
of the present
invention by generating an optical shape which effects desired changes in
power with changes in
pupil size of a particular patient under differing viewing conditions.
[0046] Fig. 26C illustrates a relationship between manifest power and pupil
diameter, for
example, as measured from patients having differing pupil diameters who have
been successfully
treated with a presbyopia-mitigating prescription. Such a relationship may be
used to identify a
desired change in optical power with changes in pupil diameter for a specific
patient.
[0047] Figs. 27A and 27B graphically illustrate optical properties of an eye
relevant to
presbyopia.
[0048] Fig. 28 schematically illustrates a presbyopia-mitigating shape having
a central add
region.
[0049] Figs. 29 and 30 schematically illustrates residual accommodation and
presbyopia
treatments for increasing a focal range.
[0050] Figs. 31-37 graphically illustrate results from presbyopia-mitigating
treatments for a
population of individual patients.
[0051] Fig. 38 graphically illustrates accommodation through a range of
differing patient ages.
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0052] Fig. 39 schematically illustrates another system for determining a
presbyopia-mitigating
prescription for a particular patient and delivering that treatment using
laser refractive surgery.
[0053] Figs. 40 and 41 graphically illustrate a presbyopia-mitigating
prescription derived so as
to provide appropriate effective powers at two differing viewing conditions
for a particular patient.
[0054] Figs. 42 and 43 graphically illustrate a presbyopia-mitigating
prescription derived so as
to provide appropriate effective powers at three differing viewing conditions
for a particular
patient.
[0055] Figs. 44 and 45 graphically illustrate a presbyopia-mitigating
prescription derived so as
to provide appropriate effective powers at four differing viewing conditions
for a particular patient.
[0056] Figs. 46A and 46B graphically illustrate different presbyopia-
mitigating prescriptions
which provide differing effective power variation characteristics during pupil
size changes under
differing viewing conditions.
[0057] Figs. 47 and 48 graphically illustrate effects of different pupil sizes
on derived
presbyopia-mitigating prescriptions and their optical characteristics.
[0058] Fig. 49 illustrates simulated eye-chart letters as viewed with a
presbyopic eye treated
with a presbyopia-mitigating prescription derived for a particular patient.
[0059] Figs. 50A and 50B illustrate an exemplary power/pupil correlation and
corresponding
presbyopia prescription.
[0060] Fig. 51 shows through-focus results for a 20/20 eye chart letter E
convolved with certain
point spread function models across a vergence range according to embodiments
of the present
invention.
[0061] Fig. 52 illustrates CMTF value curves according to embodiments of the
present
invention.
[0062] Figs. 53A and 53B depict point spread functions with ring-type and
centrally-
concentrated configurations, respectively, according to embodiments of the
present invention.
[0063] Fig. 54 shows cross sections of the point spread function images
according to
embodiments of the present invention.
[0064] Figs. 55A and 55B illustrates cross-sections for point spread functions
according to
embodiments of the present invention.
11
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0065] Fig. 56 depicts cross sections of point spread functions according to
embodiments of the
present invention.
[0066] Fig. 57 illustrates aspects of a method of evaluating an image quality
provided by a
vision treatment shape, according to embodiments of the present invention.
[0067] Fig. 58 illustrates aspects of a method of determining a compound
modulation transfer
function (CMTF) threshold value for a CMTF spatial frequency set, according to
embodiments of
the present invention.
[0068] Fig. 59 depicts aspects of methods for determining an optical surface
shape and
providing a treatment to a patient according to embodiments of the present
invention.
[0069] Fig. 60 depicts aspects of methods for generating an optical surface
shape for a patient
according to embodiments of the present invention.
[0070] Fig. 61 depicts aspects of a vision requirements specification,
according to embodiments
of the present invention.
[0071] Fig. 62 depicts aspects of a vision requirements specification,
according to embodiments
of the present invention.
[0072] Fig. 63 illustrates aspects of techniques for determining a merit
function for a target or
treatment shape based on an optical metric value for the shape at the various
viewing or testing
distances, according to embodiments of the present invention.
[0073] Figs. 64A and 64B illustrate aspects of weighting value distributions,
according to
embodiments of the present invention.
[0074] Figs. 65A, 65B, 65C, and 65D illustrate aspects of weighting value
distributions,
according to embodiments of the present invention.
[0075] Figs. 66A and 66B illustrate aspects of weighting value distributions,
according to
embodiments of the present invention.
[0076] Figs. 67A and 67B illustrate aspects of weighting value distributions,
according to
embodiments of the present invention.
[0077] Figs. 68A, 68B, and 68C illustrate example distance, intermediate, and
near vision
experienced by an eye without correction, respectively.
12
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0078] Figs. 69A, 69B, and 69C illustrate example distance, intermediate, and
near vision
experienced by an eye corrected for near vision viewing distances only,
respectively.
[0079] Figs. 70A, 70B, and 70C illustrate example distance, intermediate, and
near vision
experienced by an eye corrected for intermediate and near viewing distances,
respectively.
[0080] Figs. 71A, 71B, and 71C illustrate example distance, intermediate, and
near vision
experienced by an eye corrected for distance and intermediate viewing
distances, respectively.
DETAILED DESCRIPTION OF THE INVENTION
[0081] Although the methods, devices, and systems of the present invention are
described
primarily in the context of a laser eye surgery system, it should be
understood that the techniques
of the present invention may be adapted for use in other eye treatment
procedures and systems
such as contact lenses, intra-ocular lenses, radial keratotomy, collagenous
corneal tissue thermal
remodeling, removable corneal lens structures, glass spectacles, corneal ring
implants, and the like.
[0082] Exemplary systems and methods disclosed herein can be implemented via a
variety of
ophthalmic devices or solutions. For example, treatment techniques may be used
for any of a
variety of surgery modalities, including excimer laser surgery, femtosecond
surgery, and the like.
A variety of forms of lasers and laser energy can be used to effect a
correction or treatment,
including infrared lasers, ultraviolet lasers, femtosecond lasers, wavelength
multiplied solid-state
lasers, and the like. By way of non-limiting example, ophthalmic corrections
can involve a cornea
or lens reshaping procedure, such as, for example using a picosecond or
femtosecond laser. Laser
ablation procedures can remove a targeted amount stroma of a cornea to change
a cornea's contour
and adjust for aberrations. In some cases, a treatment protocol can involve
the delivery of a series
of discrete pulses of laser light energy, with a total shape and amount of
tissue removed being
determined by a shape, size, location, and/or number of laser energy pulses
impinging on or
focused within a cornea. In some cases, a surgical laser, such as a non-
ultraviolet, ultra-short
pulsed laser that emits radiation with pulse durations as short as nanoseconds
and femtoseconds
(e.g., a femtosecond laser, or a picosecond laser) can be used to treat the
eye of a patient. Other
pulse widths may be suitable as well. The laser systems can be configured to
deliver near infrared
light. Other wavelengths may be used as well. The laser systems can be
configured to deliver
laser light focused at a focus depth (e.g. within corneal or other
ophthalmologic tissue) which may
be controlled by the system. Laser surgery with ultra-short pulse lasers such
as femtosecond lasers
can be used to treat the eye. These pulsed lasers can make very accurate
incisions of the eye and
can be used in many ways to treat the eye. Additional types of incisions that
can be performed
13
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
with the short pulse lasers include incisions for paracentesis, limbal
relaxing incisions, and
refractive incisions to shape the cornea, for example.
[0083] In some cases, vision treatments can include focusing femtosecond laser
energy within
the stroma so as to ablate a volume of intrastromal tissue. By scanning the
focal spot within an
appropriate volume of the stromal tissue, it is possible to vaporize the
volume so as to achieve a
desired refractive alteration. Hence, embodiments of the present invention
encompass laser
surgical techniques that involve femtosecond laser photodisruption or
photoalteration treatments.
In some cases, a femtosecond laser can be used to perform the photodisruption,
thus providing an
easy, precise, and effective approach to refractive surgery
[0084] According to some embodiments, a femtosecond laser (or other laser) of
the optical
system can be used to incise the cornea or to cut a flap. A femtosecond laser
may be used to make
arcuate or other incisions in the cornea, which incisions may be customized,
intrastromal, stable,
predictable, and the like. Likewise, corneal entry incisions may be made,
which are custom, multi-
plane, and self-sealing.
[0085] Pulsed laser beams include bursts or pulses of light. Pulsed lasers,
such as non-
ultraviolet, ultra-short pulsed lasers with pulse durations measured in the
nanoseconds to
femtoseconds range, can be used in ophthalmic surgical procedures as disclosed
herein. For
example, a pulsed laser beam can be focused onto a desired area of
ophthalmologic material or
tissue, such as the cornea, the capsular bag, or the lens of the eye, to
photoalter the material in this
area and, in some instances, the associated peripheral area. Examples of
photoalteration of the
material include, but are not necessarily limited to, chemical and physical
alterations, chemical and
physical breakdown, disintegration, ablation, photodisruption, vaporization, a
the like. Exemplary
treatment systems can include a focusing mechanism (e.g. lens) and/or a
scanning mechanism so
as to guide or direct a focus of femtosecond energy along a path within the
patient's eye (e.g. at
one or more corneal subsurface locations).
[0086] According to some embodiments, the vergence weighting systems and
methods disclosed
herein can be implemented in connection with software residing in a diagnostic
device such as
WaveScan and iDesignTM devices.
[0087] Turning now to the drawings, Fig. 1 illustrates a laser eye surgery
system 10 of the
present invention, including a laser 12 that produces a laser beam 14. Laser
12 is optically coupled
to laser delivery optics 16, which directs laser beam 14 to an eye E of
patient P. A delivery optics
support structure (not shown here for clarity) extends from a frame 18
supporting laser 12. A
14
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
microscope 20 is mounted on the delivery optics support structure, the
microscope often being
used to image a cornea of eye E.
[0088] Laser 12 generally comprises an excimer laser, ideally comprising an
argon-fluorine laser
producing pulses of laser light having a wavelength of approximately 193 nm.
Laser 12 will
preferably be designed to provide a feedback stabilized fluence at the
patient's eye, delivered via
delivery optics 16. The present invention may also be useful with alternative
sources of ultraviolet
or infrared radiation, particularly those adapted to controllably ablate the
corneal tissue without
causing significant damage to adjacent and/or underlying tissues of the eye.
Such sources include,
but are not limited to, solid state lasers and other devices which can
generate energy in the
ultraviolet wavelength between about 185 and 205 nm and/or those which utilize
frequency-
multiplying techniques. Hence, although an excimer laser is the illustrative
source of an ablating
beam, other lasers may be used in the present invention.
[0089] Laser system 10 will generally include a computer or programmable
processor 22.
Processor 22 may comprise (or interface with) a conventional PC system
including the standard
user interface devices such as a keyboard, a display monitor, and the like.
Processor 22 will
typically include an input device such as a magnetic or optical disk drive, an
internet connection,
or the like. Such input devices will often be used to download a computer
executable code from a
tangible storage media 29 embodying any of the methods of the present
invention. Tangible
storage media 29 may take the form of a floppy disk, an optical disk, a data
tape, a volatile or non-
volatile memory, RAM, or the like, and the processor 22 will include the
memory boards and other
standard components of modern computer systems for storing and executing this
code. Tangible
storage media 29 may optionally embody wavefront sensor data, wavefront
gradients, a wavefront
elevation map, a treatment map, a corneal elevation map, and/or an ablation
table. While tangible
storage media 29 will often be used directly in cooperation with an input
device of processor 22,
the storage media may also be remotely operatively coupled with processor by
means of network
connections such as the internet, and by wireless methods such as infrared,
Bluetooth, or the like.
[0090] Laser 12 and delivery optics 16 will generally direct laser beam 14 to
the eye of patient P
under the direction of a computer 22. Computer 22 will often selectively
adjust laser beam 14 to
expose portions of the cornea to the pulses of laser energy so as to effect a
predetermined sculpting
of the cornea and alter the refractive characteristics of the eye. In many
embodiments, both laser
beam 14 and the laser delivery optical system 16 will be under computer
control of processor 22 to
effect the desired laser sculpting process, with the processor effecting (and
optionally modifying)
the pattern of laser pulses. The pattern of pulses may by summarized in
machine readable data of
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
tangible storage media 29 in the form of a treatment table, and the treatment
table may be adjusted
according to feedback input into processor 22 from an automated image analysis
system in
response to feedback data provided from an ablation monitoring system feedback
system.
Optionally, the feedback may be manually entered into the processor by a
system operator. Such
feedback might be provided by integrating the wavefront measurement system
described below
with the laser treatment system 10, and processor 22 may continue and/or
terminate a sculpting
treatment in response to the feedback, and may optionally also modify the
planned sculpting based
at least in part on the feedback. Measurement systems are further described in
U.S. Patent No.
6,315,413, the full disclosure of which is incorporated herein by reference.
[0091] Laser beam 14 may be adjusted to produce the desired sculpting using a
variety of
alternative mechanisms. The laser beam 14 may be selectively limited using one
or more variable
apertures. An exemplary variable aperture system having a variable iris and a
variable width slit is
described in U.S. Patent No. 5,713,892, the full disclosure of which is
incorporated herein by
reference. The laser beam may also be tailored by varying the size and offset
of the laser spot
from an axis of the eye, as described in U.S. Patent Nos. 5,683,379,
6,203,539, and 6,331,177, the
full disclosures of which are incorporated herein by reference.
[0092] Still further alternatives are possible, including scanning of the
laser beam over the
surface of the eye and controlling the number of pulses and/or dwell time at
each location, as
described, for example, by U.S. Patent No. 4,665,913, the full disclosure of
which is incorporated
herein by reference; using masks in the optical path of laser beam 14 which
ablate to vary the
profile of the beam incident on the cornea, as described in U.S. Patent No.
5,807,379, the full
disclosure of which is incorporated herein by reference; hybrid profile-
scanning systems in which
a variable size beam (typically controlled by a variable width slit and/or
variable diameter iris
diaphragm) is scanned across the cornea; or the like. The computer programs
and control
methodology for these laser pattern tailoring techniques are well described in
the patent literature.
[0093] Additional components and subsystems may be included with laser system
10, as should
be understood by those of skill in the art. For example, spatial and/or
temporal integrators may be
included to control the distribution of energy within the laser beam, as
described in U.S. Patent
No. 5,646,791, the full disclosure of which is incorporated herein by
reference. Ablation effluent
evacuators/filters, aspirators, and other ancillary components of the laser
surgery system are
known in the art. Further details of suitable systems for performing a laser
ablation procedure can
be found in commonly assigned U.S. Pat. Nos. 4,665,913, 4,669,466, 4,732,148,
4,770,172,
4,773,414, 5,207,668, 5,108,388, 5,219,343, 5,646,791 and 5,163,934, the
complete disclosures of
16
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
which are incorporated herein by reference. Suitable systems also include
commercially available
refractive laser systems such as those manufactured and/or sold by Alcon,
Bausch & Lomb, Nidek,
WaveLight, LaserSight, Schwind, Zeiss-Meditec, and the like. Basis data can be
further
characterized for particular lasers or operating conditions, by taking into
account localized
environmental variables such as temperature, humidity, airflow, and
aspiration.
[0094] Fig. 2 is a simplified block diagram of an exemplary computer system 22
that may be
used by the laser surgical system 10 of the present invention. Computer system
22 typically
includes at least one processor 52 which may communicate with a number of
peripheral devices
via a bus subsystem 54. These peripheral devices may include a storage
subsystem 56, comprising
a memory subsystem 58 and a file storage subsystem 60, user interface input
devices 62, user
interface output devices 64, and a network interface subsystem 66. Network
interface subsystem
66 provides an interface to outside networks 68 and/or other devices, such as
the wavefront
measurement system 30.
[0095] User interface input devices 62 may include a keyboard, pointing
devices such as a
mouse, trackball, touch pad, or graphics tablet, a scanner, foot pedals, a
joystick, a touchscreen
incorporated into the display, audio input devices such as voice recognition
systems, microphones,
and other types of input devices. User input devices 62 will often be used to
download a computer
executable code from a tangible storage media 29 embodying any of the methods
of the present
invention. In general, use of the term "input device" is intended to include a
variety of
conventional and proprietary devices and ways to input information into
computer system 22.
[0096] User interface output devices 64 may include a display subsystem, a
printer, a fax
machine, or non-visual displays such as audio output devices. The display
subsystem may be a
cathode ray tube (CRT), a flat-panel device such as a liquid crystal display
(LCD), a projection
device, or the like. The display subsystem may also provide a non-visual
display such as via audio
output devices. In general, use of the term "output device" is intended to
include a variety of
conventional and proprietary devices and ways to output information from
computer system 22 to
a user.
[0097] Storage subsystem 56 can store the basic programming and data
constructs that provide
the functionality of the various embodiments of the present invention. For
example, a database
and modules implementing the functionality of the methods of the present
invention, as described
herein, may be stored in storage subsystem 56. These software modules are
generally executed by
processor 52. In a distributed environment, the software modules may be stored
on a plurality of
17
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
computer systems and executed by processors of the plurality of computer
systems. Storage
subsystem 56 typically comprises memory subsystem 58 and file storage
subsystem 60.
[0098] Memory subsystem 58 typically includes a number of memories including a
main
random access memory (RAM) 70 for storage of instructions and data during
program execution
and a read only memory (ROM) 72 in which fixed instructions are stored. File
storage subsystem
60 provides persistent (non-volatile) storage for program and data files, and
may include tangible
storage media 29 (Fig. 1) which may optionally embody wavefront sensor data,
wavefront
gradients, a wavefront elevation map, a treatment map, and/or an ablation
table. File storage
subsystem 60 may include a hard disk drive, a floppy disk drive along with
associated removable
media, a Compact Digital Read Only Memory (CD-ROM) drive, an optical drive,
DVD, CD-R,
CD-RW, solid-state removable memory, and/or other removable media cartridges
or disks. One or
more of the drives may be located at remote locations on other connected
computers at other sites
coupled to computer system 22. The modules implementing the functionality of
the present
invention may be stored by file storage subsystem 60.
[0099] Bus subsystem 54 provides a mechanism for letting the various
components and
subsystems of computer system 22 communicate with each other as intended. The
various
subsystems and components of computer system 22 need not be at the same
physical location but
may be distributed at various locations within a distributed network. Although
bus subsystem 54
is shown schematically as a single bus, alternate embodiments of the bus
subsystem may utilize
multiple busses.
[0100] Computer system 22 itself can be of varying types including a personal
computer, a
portable computer, a workstation, a computer terminal, a network computer, a
control system in a
wavefront measurement system or laser surgical system, a mainframe, or any
other data processing
system. Due to the ever-changing nature of computers and networks, the
description of computer
system 22 depicted in Fig. 2 is intended only as a specific example for
purposes of illustrating one
embodiment of the present invention. Many other configurations of computer
system 22 are
possible having more or less components than the computer system depicted in
Fig. 2.
[0101] Referring now to Fig. 3, one embodiment of a wavefront measurement
system 30 is
schematically illustrated in simplified form. In very general terms, wavefront
measurement system
30 is configured to sense local slopes of a gradient map exiting the patient's
eye. Devices based
on the Hartmann-Shack principle generally include a lenslet array to sample
the gradient map
uniformly over an aperture, which is typically the exit pupil of the eye.
Thereafter, the local slopes
of the gradient map are analyzed so as to reconstruct the wavefront surface or
map.
18
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0102] More specifically, one wavefront measurement system 30 includes an
image source 32,
such as a laser, which projects a source image through optical tissues 34 of
eye E so as to form an
image 44 upon a surface of retina R. The image from retina R is transmitted by
the optical system
of the eye (e.g., optical tissues 34) and imaged onto a wavefront sensor 36 by
system optics 37.
The wavefront sensor 36 communicates signals to a computer system 22 for
measurement of the
optical errors in the optical tissues 34 and/or determination of an optical
tissue ablation treatment
program. Computer 22' may include the same or similar hardware as the computer
system 22
illustrated in Figs. 1 and 2. Computer system 22' may be in communication with
computer system
22 that directs the laser surgery system 10, or some or all of the components
of computer system
22, 22' of the wavefront measurement system 30 and laser surgery system 10 may
be combined or
separate. If desired, data from wavefront sensor 36 may be transmitted to a
laser computer system
22 via tangible media 29, via an I/0 port, via an networking connection 66
such as an intranet or
the Internet, or the like.
[0103] Wavefront sensor 36 generally comprises a lenslet array 38 and an image
sensor 40. As
the image from retina R is transmitted through optical tissues 34 and imaged
onto a surface of
image sensor 40 and an image of the eye pupil P is similarly imaged onto a
surface of lenslet array
38, the lenslet array separates the transmitted image into an array of
beamlets 42, and (in
combination with other optical components of the system) images the separated
beamlets on the
surface of sensor 40. Sensor 40 typically comprises a charged couple device or
"CCD," and senses
the characteristics of these individual beamlets, which can be used to
determine the characteristics
of an associated region of optical tissues 34. In particular, where image 44
comprises a point or
small spot of light, a location of the transmitted spot as imaged by a beamlet
can directly indicate a
local gradient of the associated region of optical tissue.
[0104] Eye E generally defines an anterior orientation ANT and a posterior
orientation POS.
Image source 32 generally projects an image in a posterior orientation through
optical tissues 34
onto retina R as indicated in Fig. 3. Optical tissues 34 again transmit image
44 from the retina
anteriorly toward wavefront sensor 36. Image 44 actually formed on retina R
may be distorted by
any imperfections in the eye's optical system when the image source is
originally transmitted by
optical tissues 34. Optionally, image source projection optics 46 may be
configured or adapted to
decrease any distortion of image 44.
[0105] In some embodiments, image source optics 46 may decrease lower order
optical errors by
compensating for spherical and/or cylindrical errors of optical tissues 34.
Higher order optical
errors of the optical tissues may also be compensated through the use of an
adaptive optic element,
19
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
such as a deformable mirror (described below). Use of an image source 32
selected to define a
point or small spot at image 44 upon retina R may facilitate the analysis of
the data provided by
wavefront sensor 36. Distortion of image 44 may be limited by transmitting a
source image
through a central region 48 of optical tissues 34 which is smaller than a
pupil 50, as the central
portion of the pupil may be less prone to optical errors than the peripheral
portion. Regardless of
the particular image source structure, it will be generally be beneficial to
have a well-defined and
accurately formed image 44 on retina R.
[0106] In one embodiment, the wavefront data may be stored in a computer
readable medium 29
or a memory of the wavefront sensor system 30 in two separate arrays
containing the x and y
wavefront gradient values obtained from image spot analysis of the Hartmann-
Shack sensor
images, plus the x and y pupil center offsets from the nominal center of the
Hartmann-Shack
lenslet array, as measured by the pupil camera 51 (Fig. 3) image. Such
information contains all
the available information on the wavefront error of the eye and is sufficient
to reconstruct the
wavefront or any portion of it. In such embodiments, there is no need to
reprocess the Hartmann-
Shack image more than once, and the data space required to store the gradient
array is not large.
For example, to accommodate an image of a pupil with an 8 mm diameter, an
array of a 20 x 20
size (i.e., 400 elements) is often sufficient. As can be appreciated, in other
embodiments, the
wavefront data may be stored in a memory of the wavefront sensor system in a
single array or
multiple arrays.
[0107] While the methods of the present invention will generally be described
with reference to
sensing of an image 44, a series of wavefront sensor data readings may be
taken. For example, a
time series of wavefront data readings may help to provide a more accurate
overall determination
of the ocular tissue aberrations. As the ocular tissues can vary in shape over
a brief period of time,
a plurality of temporally separated wavefront sensor measurements can avoid
relying on a single
snapshot of the optical characteristics as the basis for a refractive
correcting procedure. Still
further alternatives are also available, including taking wavefront sensor
data of the eye with the
eye in differing configurations, positions, and/or orientations. For example,
a patient will often
help maintain alignment of the eye with wavefront measurement system 30 by
focusing on a
fixation target, as described in U.S. Patent No. 6,004,313, the full
disclosure of which is
incorporated herein by reference. By varying a position of the fixation target
as described in that
reference, optical characteristics of the eye may be determined while the eye
accommodates or
adapts to image a field of view at a varying distance and/or angles.
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0108] The location of the optical axis of the eye may be verified by
reference to the data
provided from a pupil camera 52. In the exemplary embodiment, a pupil camera
52 images pupil
50 so as to determine a position of the pupil for registration of the
wavefront sensor data relative to
the optical tissues.
[0109] An alternative embodiment of a wavefront measurement system is
illustrated in Fig. 3A.
The major components of the system of Fig. 3A are similar to those of Fig. 3.
Additionally, Fig.
3A includes an adaptive optical element 53 in the form of a deformable mirror.
The source image
is reflected from deformable mirror 98 during transmission to retina R, and
the deformable mirror
is also along the optical path used to form the transmitted image between
retina R and imaging
sensor 40. Deformable mirror 98 can be controllably deformed by computer
system 22 to limit
distortion of the image formed on the retina or of subsequent images formed of
the images formed
on the retina, and may enhance the accuracy of the resultant wavefront data.
The structure and use
of the system of Fig. 3A are more fully described in U.S. Patent No.
6,095,651, the full disclosure
of which is incorporated herein by reference.
[0110] The components of an embodiment of a wavefront measurement system for
measuring
the eye and ablations may comprise elements of a WaveScan , available from AMO
Manufacturing USA, LLC in Milpitas, California. One embodiment includes a
WaveScan with a
deformable mirror as described above. An alternate embodiment of a wavefront
measuring system
is described in U.S. Patent No. 6,271,915, the full disclosure of which is
incorporated herein by
reference. It is appreciated that any wavefront aberrometer could be employed
for use with the
present invention. Relatedly, embodiments of the present invention encompass
the
implementation of any of a variety of optical instruments provided by Abbott
Medical Optics, Inc.,
including the iDesign system, and the like.
[0111] Relatedly, embodiments of the present invention encompass the
implementation of any
of a variety of optical instruments provided by WaveFront Sciences, Inc.,
including the COAS
wavefront aberrometer, the ClearWave contact lens aberrometer, the CrystalWave
IOL
aberrometer, and the like. Embodiments of the present invention may also
involve wavefront
measurement schemes such as a Tscherning-based system, which may be provided
by WaveFront
Sciences, Inc. Embodiments of the present invention may also involve wavefront
measurement
schemes such as a ray tracing-based system, which may be provided by Tracey
Technologies,
Corp.
[0112] The present invention is useful for enhancing the accuracy and efficacy
of
photorefractive keratectomy (PRK), laser in situ keratomileusis (LASIK), laser
assisted epithelium
21
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
keratomileusis (LASEK), and the like. The present invention can provide
enhanced optical
correction approaches by improving the methodology for scaling an optical
shape, or by generating
or deriving new optical shapes, and the like.
[0113] The techniques of the present invention can be readily adapted for use
with existing laser
systems, including the Excimer laser eye surgery systems commercially
available from AMO
Manufacturing USA, LLC in Milpitas, California. Other suitable laser systems
are manufactured
by Alcon, Bausch & Lomb, Wavelight, Schwind, Zeiss-Meditec, Lasersight, Nidek
and the like.
By providing improved corneal ablation profiles for treating optical defects,
the present invention
may allow enhanced treatment of patients who have heretofore presented
difficult or complicated
treatment problems. When used for determining, deriving, and/or optimizing
prescriptions for a
particular patient, the systems and methods may be implemented by calculating
prescriptions for a
range of patients, for example, by calculating discrete table entries
throughout a range of patient
characteristics, deriving or empirically generating parametric patient
characteristic/prescription
correlations, and the like, for subsequent use in generating patient-specific
prescriptions.
[0114] When designing a prescriptive shape for an eye treatment, it is useful
to select a
mathematical gauge of optical quality appropriate for the vision condition for
use as a goal
function. This allows for quantification and optimization of the shape, and
for comparison among
different shapes. The present invention provides methods for establishing a
customized optical
shape for a particular patient based on a set of patient parameters per the
goal function. By
incorporating iterative optimization algorithms, it is also possible to
generate a shape having an
optimized level of optical quality for the particular patient.
[0115] Selecting A Goal Function Appropriate For A Vision Condition
[0116] The goal function relates to optical quality, and it can be, for
example, based on, or a
function of (or related to) optical metrics such as Strehl ratio (SR),
modulation transfer function
(MTF), point spread function (PSF), encircled energy (EE), MTF volume or
volume under MTF
surface (MTFV), or contrast sensitivity (CS); and optionally to new optical
metrics which are
appropriate to vision conditions such as presbyopia; for instance, compound
modulation transfer
function (CMTF) as described below. In optical terms, the goal function should
make sense. That
is to say, minimization or maximization of the goal function should give a
predictable optimized
optical quality of the eye. The goal function can be a function with a certain
number of free
parameters to be optimized (minimized) through an optimization, or
minimization, algorithm.
[0117] Although there are many types of goal functions available for use with
the present
invention, the discussion below generally touches on two broad schools of goal
functions. In a
22
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
Diffraction Theory based approach, the shape is considered as a wave
aberration. Typically, a
Fourier transform is employed for calculating optical quality related
parameters, such as Strehl
ratio (SR), modulation transfer function (MTF), MTF volume or volume under MTF
surface
(MTFV), compound modulation transfer function (CMTF), or contrast sensitivity
(CS), encircled
energy (EE) (based on point spread function), as well as special cases that
combine one or more of
these parameters, or values of the parameters in specific situations (such as
MTF at spatial
frequency or encircled energy at a field of view), or integration of any
parameters (volume of MTF
surface at all frequencies or up to a cutoff frequency, for example 60
cycles/degree or 75
cycles/degree, because 60 cycles/degree is the retina cone's limiting spatial
frequency). In a
Geometrical Optics approach, or the so-called ray tracing approach, the
optical effect is based on
ray tracing. With both the Diffraction Theory and the Geometrical Optics
approaches,
polychromatic point spread function with Stiles-Crawford effect, chromatic
aberrations as well as
retina spectral response function can be used.
[0118] Monochromatic point spread function (PSF) has been used for describing
optical defects
of optical systems having aberrations. Due to the simple relationship between
wave aberrations
and the PSF for an incoherent light source, Fourier transform of the
generalized pupil function has
been used in the calculation of point spread functions. Most optical
applications, however, do not
use a monochromatic light source. In the case of human vision, the source is
essentially white
light. Thus, there are limitations associated with the use of monochromatic
PSF as a goal function.
[0119] Polychromatic point spread function (PSF) with correct chromatic
aberrations, Stiles-
Crawford effect as well as retina response function, can be used for optical
modeling of human
eyes. Here, chromatic aberrations arise because light composed of different
wavelengths will
focus either in front of the retina or behind it. Only portions of the light
will focus exactly on the
retina. This gives the eye an extended depth-of-focus, i.e., if one has
focusing error of some
amount, the eye is still capable of focusing at least for some wavelengths.
Therefore, chromatic
aberrations in fact help the correction of presbyopia. If the depth-of-focus
is sufficiently large,
there would be no presbyopia problem. Unfortunately, the chromatic aberrations
are not large
enough and it also varies with the wavelength. Stiles-Crawford effect, also
known as pupil
apodization, is due to the waveguide property of the retinal cones. Light from
the pupil periphery
has a slightly less chance of being detected by the retina because the ray of
light might not reach
the bottom of the cone, due to a slight incident angle. As for the retinal
spectral response function,
it is known that the cones, which are responsible for daylight vision, have
different sensitivity to
23
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
different wavelengths. Only green light is absorbed by the eye almost
completely. Both blue light
and red light are absorbed by the eye partially.
[0120] Once the PSF is calculated, calculation of the Strehl ratio is
straightforward. Strehl ratio
can be defined as the ratio of the peak of the point spread function (PSF) of
an optical system to
the peak of a diffraction-limited optical system with the same aperture size.
An example of a
Strehl ratio is shown in Fig. 27A. A diffraction-limited optical system is
typically a system with
no aberrations, or optical errors. It can be an ideal or perfect optical
system, having a Strehl ratio
of 1.
[0121] The goal function can also be a function of modulation transfer
function (MTF).
Modulation transfer function can be used to predict visual performance.
Typically, the MTF at
one spatial frequency corresponds to one angular extend of features of
targets. The modulation
transfer function (MTF) can be calculated with the following formulations:
MTF(u,v) = FT[PSF(x,y)]
MTF(u,v) = Re[GPF(x,y) 0 GPF(x,y)]
where u and v represent spatial frequencies, Re represents the real part of a
complex number, FT
represents a Fourier Transform, GPF represents a generalized pupil function,
and x and y represent
position or field of view. An example of an MTF is shown in Fig. 27B.
[0122] Modulation transfer function (MTF) is a measure for how much spatial
details are
transferred from pupil space to imaging space (retina in the case of human
eye). MTF can be
related to contrast sensitivity (CS). Mathematically MTF can be defined as the
Fourier transform
of the point spread function as
h(u,v) = H i(x, y) exp[¨i2z(ux + vy)]clxdy, ,
where i(x,y) is the point spread function (PSF). Calculation of PSF can be
done with the Fourier
transform of the generalized pupil function.
[0123] MTF at a specific spatial frequency can represent the percentage of the
sinusoidal wave
of a specific spatial frequency that is preserved after going through the
optical system. MTF at 30
cycles/degree and at 60 cycles/degree are considered as important because 30
cpd corresponds to
20/20 visual acuity and 60 cpd corresponds to 20/10 visual acuity, the highest
spatial resolution the
cones in the retinal can process. MTF at other spatial frequencies may also be
useful.
24
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0124] The volume under the MTF surface up to a certain spatial frequency
(such as 60 cpd) can
be meaningful as it includes all spatial frequency information. In some cases,
it is desirable to use
the volume under MTF surface within a band (i.e. from one specific spatial
frequency to another
specific spatial frequency).
Compound Modulation Transfer Function
[0125] Compound MTF can be calculated as a linear combination of MTF at
certain spatial
frequencies, normalized at diffraction-limited MTF, and can be represented by
the following
formula
CMTF = 1 ¨ L a ihi ,
n
where n is the number of MTF curves, oci is the reciprocal of the ith
diffraction-limited MTF, and h,
is the ith MTF curve. The selection of certain spatial frequencies can depend
on the importance of
each frequency. For example, in the case of presbyopia, 20/40 vision may be
more important than
20/20 as the distance vision is often compromised by the improved near vision.
Figs 4A and 4B
show an examples of an CMTF curve as well as its individual MTF curves at
different specific
spatial frequencies. In a perfect optical system, CMTF is equal to one.
[0126] In a related embodiment, the compound MTF can be calculated as
F(v) = (a1MTF1 + a2MTF2 + a,MTF, )13
where MTFi, MTF2, and MTF3 are the MTF values at 10 cycles/degree, 20
cycles/degree and 30
cycles/degree, respectively. These correspond to Snellen eye chart of 20/60,
20/40 and 20/20
visions, respectively. The weighting coefficients oc1, oc2, oc3 can be chosen
so that 1/oci, 1/oc2, 1/0c3
are the diffraction-limited MTF at these spatial frequencies, respectively.
Therefore, in the
diffraction-limited case, the compound MTF F(v) can have a maximal value of
unity.
[0127] Where MTF at one spatial frequency corresponds to one angular extend of
features of
targets, compound MTF can be calculated as linear combination of MTF at
different spatial
frequencies normalized by a diffraction-limited MTF, and can similarly be used
to predict visual
outcome. Another general formula for the calculation of CMTF as a function of
visual vergence
(nu) is
n
CMTF (v) = 1 ¨IaiMTF,(v)
n i_1
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
where a, is the reciprocal of the i-th diffraction-limited MTF. This formula
can provide CMTF for
all possible vergence. In some cases, three MTF curves at 10, 20 and 30 cycles
per degree are
used. An ideal value of CMTF can be about 1. Good values can be about 0.2 or
about 0.3. In a
healthy eye, the spatial frequency limit can be about 60 cycles per degree due
to the configuration
of retina cones. However, in the treatment of presbyopia, for example, it may
not be necessary to
provide a treatment corresponding to this limit, as the treatment will often
involve a compromise
of good distance and near sight. Optionally, a minimum distance vision gauge
desired target may
be provided, with near sight being optimized and, as needed, compromised.
[0128] Fig. 4A illustrates an example of the compound MTF over a vergence of 3
diopters
(upper panel) versus its corresponding individual MTF curves at 15, 30, and 60
cycles per degree
(lower panel). Fig. 4B illustrates an example of the compound MTF over a
vergence of 3 diopters
(upper panel) versus its corresponding individual MTF curves at 10, 20, and 30
cycles per degree
(lower panel). Compound MTF can correlate well with visual acuity and contrast
sensitivity at the
same time, at least optically. In some embodiments, the compound modulation
transfer function is
determined for individual MTF curves at 30, 45, and 60 cpd. The selection of
the individual MTF
curve values can involve a linear combination based on the optical response of
the eye.
[0129] In general, there can be two different types of cutoff spatial
frequencies, and each
involves a factors that affect acuity. Cutoff spatial frequency can correspond
to the maximum
spatial frequency, above which information can no longer be used. Whereas most
individuals can
discern information from objects having very low spatial frequency, as the
spatial frequency
increases, it is typically increasingly more difficult for an individual to
discern information from
such objects. At some threshold, an increased spatial frequency no longer
yields increased
information.
[0130] A first type of cutoff spatial frequency is related to aperture
dimension. In this case, a
system having a larger aperture (e.g. an eye with a larger pupil) will
correspond to a larger cutoff
spatial frequency. Conversely, a system having a smaller aperture (e.g. an eye
with a smaller
pupil) will correspond to a smaller cutoff spatial frequency. Often, such
cutoff spatial frequencies
will be linearly dependent on a pupil dimension, for example the pupil
diameter. Smaller pupil
sizes typically correspond to an extended, or larger, depth of focus.
Relatedly, smaller pupil sizes
often result in lower resolution. Assuming there are no aberrations, a larger
pupil size is thought to
confer increased resolution.
[0131] A second type of cutoff spatial frequency typically depends on the
spacing of cones on
the retina of the eye. With this type of cutoff spatial frequency, the
standard value is 30 cpd,
26
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
which corresponds to 20/20 vision. Another value, 60 cpd, corresponds to 20/10
vision and is
often considered a physiological limit. In such cases, the retinal cones are
very closely spaced.
The spacing of retinal cones will vary among individuals.
[0132] In the example of presbyopia treatment, it may be desirable to maintain
a lower spatial
frequency. In some cases, presbyopia will involve a compromise between
distance and near
vision. It may be difficult to achieve high spatial resolution, thus enhancing
the desirability of
emphasizing lower and medium spatial frequency information. In other words,
high spatial
frequency information may be sacrificed in order to improve the combination of
near and distance
vision.
[0133] As noted above, a compound modulation transfer function can include
individual MTF
curves at various combinations of spatial frequencies, such as 15, 30, and 60
cycles per degree and
10, 20, and 30 cycles per degree. An individual MTF can have a value ranging
from about 5
cycles per degree to about 75 cycles per degree. In many instances, at least
one individual MTF of
a CMTF will range from about 10 cycles per degree to about 30 cycles per
degree, and can often
be about 20 cycles per degree. Where a CMTF includes three individual MTF's, a
first individual
MTF can range from about 5 cycles per degree to about 20 cycles per degree, a
second individual
MTF can range from about 15 cycles per degree to about 45 cycles per degree,
and a third
individual MTF can range from about 30 cycles per degree to about 75 cycles
per degree. In some
circumstances, the upper limit of an individual MTF can be about 60 cycles per
degree.
[0134] In some cases, the CMTF will be based on an average of the individual
MTF curves. In
some embodiments, the present invention provides compound modulation transfer
functions that
correspond to three, four, five, or any number of individual modulation
transfer functions. For
example, a CMTF can include from about 2 to about 7 individual MTF's. A CMTF
can also
include from about 3 to about 6 individual MTF's.
[0135] Individual MTF's can correspond to a curve through a certain vergence.
Typically, a
target at a far distance corresponds to a small vergence value. As a target
moves closer to the eye,
the vergence increases. The individual MTF's can be based on a value ranging
from about zero to
about three diopters.
[0136] The individual MTF's can be selected based on any number of criteria,
such as empirical
data or clinical observations. Relatedly, individual MTF's can be chosen for
pure testing purposes.
The CMTF can provide a parameter to evaluate the effectiveness of a treatment
for a vision
condition, such as presbyopia. Often, the CMTF will correlate with a
particular visual outcome.
27
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0137] To establish an optically optimized shape appropriate for a vision
condition, at least one
of the goal functions, such as Strehl ratio, encircled energy, or MTF, MTF
volume or volume
under MTF surface (MTFV), compound modulation transfer function (CMTF), or
contrast
sensitivity (CS) should be maximized. For improved vision condition treatment,
the optical metric
can be maximized in all target vergence, that is, for targets at all
distances. Furthermore, it is also
desirable to minimize the fluctuation of the goal function. Therefore, the
goal function, which is
incorporated into the optimization algorithm of the optimizer, can be defined
as
svo dv
0(c. , c 2 ,..., PAR) = (1+ o-)(1+ PV) _________
Svo
o F (v)dv
[0138] where 0 is the goal function; cl, c2, ... are the polynomial
coefficients; PAR is
presbyopia-add to pupil ratio (described below); v is the vergence; F(v) is
one of the optical
metrics; 6 is the standard deviation of F(v), PV is the peak-to-valley of
F(v); and vo is the end point
of the vergence range, which may be (for example) between 15 and 100 cm, such
as 40 cm.
Because fdv is a constant, either a smaller a or a larger fF(v)dv can minimize
the goal function
O.
[0139] The formulas given here are examples of the many formulae that can be
used as the goal
function. The basic approach will often be to provide a goal function that is
optimized to give as
practical a solution as possible for correction or treatment of the vision
condition.
[0140] The compound MTF may reflect to what extent information is being
modulated when
passing through an optical system. For example, CMTF can represent the
percentage of
information at different spatial frequencies that is retained.
28
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
Selecting An Iterative Optimization Algorithm
[0141] Any of a number of optimization algorithms may be used by the optimizer
to maximize,
minimize, or otherwise globally or locally optimize the goal function. Because
many numerical
algorithms use function minimization concept, it is often convenient, but not
necessarily required,
to use minimization of the goal function. As examples, N-dimensional
minimization algorithms
such as the Downhill Simplex method, the Direction Set method, and the
Simulated Annealing
method can be used to optimize the goal function. Likewise, the algorithm
described by Press et
al., in "Numerical Recipes in C++", Cambridge University Press, 2002 can also
be used.
Algorithms such as those listed above are often used for function optimization
in multi-
dimensional space.
[0142] The Downhill Simplex method starts with an initialization of N+1 points
or vertices to
construct a simplex for an N-dimensional search, and in every attempt tries to
reflect, stretch, or
shrink the simplex by geometrical transformation so that a close-to-global
minimum or pre-defined
accuracy can be found. When Gaussian random noise of standard deviation of
0.02 pm in optical
path difference (OPD) is added, the algorithm still converges, with no
degradation.
[0143] In the case of Direction Set method, also known as Powell's method, N
one-dimensional
vectors are initialized and the N-dimensional search is split in such a way
that a one N-dimensional
vector is chosen and the minimization is done in that direction while other
variables (N-1
dimensions) are fixed. This process is continued until all dimensions are
covered. A new iteration
is initiated until the pre-determined criterion is met. The Direction Set
method can use a separate
one-dimensional minimization algorithm such as a Golden section search.
[0144] The Simulated Annealing method, which is useful for dealing with a
large number of
uncertainties, starts with an initial configuration. The objective is to
minimize E (analog to
energy) given the control parameter T (analog to temperature). Simulated
Annealing is analogous
to annealing, is a recent, proven method to solve otherwise intractable
problems, and may be used
to solve the ablation equation in laser ablation problem. This is more fully
described in PCT
Application No. PCT/US01/08337, filed March 14, 2001, and in U.S. Patent No.
6,673,062, issued
January 6, 2004, the entire disclosures of which are incorporated herein by
reference. Simulated
annealing is a method that can be used for minimizing (or maximizing) the
parameters of a
function. It is particularly suited to problems with very large, poorly
behaved function spaces.
Simulated annealing can be applied in the same way regardless of how many
dimensions are
present in the search space. It can be used to optimize any conditions that
can be expressed
29
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
numerically, and it does not require a derivative. It can also provide an
accurate overall minimum
despite local minima in the search space, for example.
[0145] Fig. 5 shows the flow chart of an overall method for shape optimization
for a vision
condition treatment. Each functional block may contain one or more
alternatives. To create an
add-on shape W(r) for a vision condition treatment, an iterative function
minimization algorithm
can be employed such that the goal function, which could be a function of any
suitable optical
metrics (e.g. CMTF) is itself optimized to solve for an unknown shape. The
shape can be
expanded into a set of even power term polynomials (EPTP) or non-EPTP (i.e.
all power term
polynomials). EPTP refers to polynomials that only have the even power terms,
for instance, F(r)
= ar2 + br4 + cr6. The goal function should have good correlation with visual
performance, at least
optically. Point spread function can be calculated to obtain additional and/or
alternative optical
metrics. The vision condition prescription can refer to an optical surface
that can be used to treat
or mitigate the vision condition. It can correspond to, for example, the shape
of a spectacle lens, a
contact lens, an intra-ocular lens, a tissue ablation profile for refractive
surgery, and the like.
[0146] Another representation of the data flow process is depicted in the flow
chart in Fig. 6,
which shows data flow for shape optimization for presbyopia correction. Again,
each functional
block may contain one or more alternatives.
[0147] It is desirable that the optimizer provide satisfactory outcome in
terms of attributes such
as result, convergence, and speed. Fig. 7 shows a comparison of Direction Set
method and
Downhill Simplex method for the following inputs: pupil size 5.6 mm, vergence
3D and vergence
step 0.1D. Direction Set method uses 17 iterations and Downhill Simplex method
uses 152
iterations. Each Direction Set method iteration takes longer than each
Downhill Simplex method
iteration. The optimizer value for the Direction Set method is 2.8 while that
for the Downhill
Simplex method is 2.658. Shape for left panel is as ¨0.9055r2+6.4188r4-
2.6767r6+0.5625r8 with
ratio of 0.7418.
[0148] Both algorithms seem to converge to a similar shape, although the
depths of the shapes
are different. Considering the difference in the pupil ratio, however, the
actual shapes within 70%
of the pupil radius are quite close. When the vergence step is smaller, each
iteration can take a
longer time, but the overall number of iterations often tends to become
smaller.
Inputting An Initial Prescription Into an Optimizer
[0149] The initial prescription, often comprising an optical surface shape,
may be defined by an
expansion such as a polynomial (EPTP, non-EPTP), a Zernike polynomial, a
Fourier series, or a
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
discrete shape entirety. A discrete shape entirety can also be referred to as
a direct surface
representation by numerical grid values. The prescription shape may be assumed
to be circularly
or radially symmetric, with the aim of approaching an emmetropic eye. The
symmetric shape can
be decomposed into a set of polynomials, such that it has one or more
independent variables. One
of the variables can be the presbyopia-add to pupil ratio (PAR), or the ratio
of the shape diameter
to the pupil diameter. When a central power add region is employed (as
described below), the
PAR can be the ratio of the radius of the presbyopia-add to the radius of the
pupil. It will also be
appreciated that the ratios discussed herein can be based on area ratios or on
diameter or radius
ratios. It should be assumed that when diameter or radius ratios are
discussed, that discussion also
contemplates area ratios. In certain cases, the PAR can range from about 0.2
to about 1Ø
Relatedly, in some cases the methods of the present invention can constrain
the PAR to range from
about 0.2 to about 1Ø The other variables can be the coefficients of each
polynomial term. For
example,
Shape(r) = ar + br2 + cr3 + dr4 + er5 + fr6
[0150] The diameter of the shape can be larger than the pupil size, but if so
special
considerations may need to be taken. For example, it may be necessary to only
consider the net
shape within the pupil.
[0151] The polynomials can be normal polynomials or polynomials with even
power terms only.
For example, even-power-term polynomials (EPTP) up to the 6th or 8th order can
be used to obtain
a practically good output, that is, a practical optimal shape for the
particular patient. Residual
accommodation can also play an active role in presbyopia correction. In a
related instance, normal
presbyopes can be treated with the prescription obtained in this approach
together with a
prescription for the correction of the refractive error.
[0152] As an example, a circularly or radially symmetric, pupil-size dependent
shape for
presbyopia-add can be assumed for emmetropic presbyopes. The shape can then be
expanded to
polynomials up to the 6th or 8th order. With the optimization procedure, it is
found that polynomial
expansion of the shape up to the 6th or 8th order can be used to obtain a
practical optimal shape for
presbyopia correction.
[0153] In a wavefront with aberrations, denoted by W(r, 0), the wavefront can
be thought of as
an optimal shape for vision correction. The polychromatic PSF can be expressed
as
31
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
2
(
PSF =IRO FFT pc(r) exp j 211-
[IV (r, 0) + c0(2) + V(l) + RA(1)1
A _
where R(2\,) is the retina spectral response function and can be approximated
to
R(2) = e-3 2
and P(r) is the pupil apodization function (Stiles-Crawford) and can be
written as
r2
Põ(r) =10 R
and DO is chromatic aberration at wavelength X and is close to
= ¨21.587 + 92.872 ¨134.9822 + 67.40723
and V(/) is the vergence induced aberration at distance 1 meters, and RA(1) is
the residual
accommodation induced aberrations with a different sign as compared to V(/).
When there are no
aberrations, RA(1) can cancel V(/) as long as there is enough residual
accommodation in the eye.
Here, the central wavelength X is taken as 0.55 pm (as all wavelength units in
the above formulae
are in pm). The pupil apodization strength parameter p is taken as 0.06. a is
the conversion factor
from diopter to optical path difference (OPD). FFT denotes a fast Fourier
transform and I*1
denotes the module of a complex number.
[0154] The polychromatic point spread function, or PPSF, can be the point
spread function of an
eye as calculated with consideration of the polychromatic nature of the
incident light. Further, the
chromatic aberrations, the Stiles-Crawford effect, as well as the retinal
spectral response function
can also be considered.
[0155] The vergence induced aberration, or VIA, can be equal to the reciprocal
of the vergence
distance. When a target at a certain distance is viewed by the eye, it is the
same as viewing the
target at infinity but the eye has an additional aberration, the vergence
induced aberration.
[0156] For emmetropic eyes, it may be desirable that the wavefront that is
optimized be
circularly symmetric. Therefore, it can be decomposed into a set of
polynomials (non-EPTP) as
W(r) = ar + br2 + cr3 + dr4 + er5 + = = =
[0157] However, if it is desirable that the edge of the shape be smoother, it
may be advantageous
to decompose the wavefront into a set of even-power-term polynomials (EPTP) as
W(r) = ar2 + br4 + cr6 + dr8 + = = =
[0158] Using even power term polynomials (EPTP) also can help to establish a
surface shape
that is more round at the center, which creates certain manufacturing or
ablation efficiencies.
32
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0159] It may also be useful to denote another parameter, t, to be the ratio
of the radius of the
wavefront R to the radius of the pupil Ro. This is because both D(/1) and V(/)
can have the same
size as the pupil and W(r) usually has a smaller size. When the calculated t
is larger than 1, the
shape can become larger than the pupil. In this case, only the portion of the
shape up to the pupil
size is used for optical quality evaluation.
[0160] As depicted in Fig. 8A, although normal polynomials can give slightly
better optimizer
values than even-power-term polynomials, the prescription may be harder to
realize. Fig. 8A
illustrates a comparison of shapes with normal polynomials (left panel) and
with even-power-term
polynomials (right panel). The shape on the right panel can be expanded as
¨1.6154r + 1.7646r2+
1.2646r3+ 1.9232r4+ 0.1440r5+ 0.1619r6 with a ratio of 0.8 and the shape on
the left panel can be
expanded as ¨1.1003r2+8.2830r4+0.7305r6-2.2140r8 with a ratio of 0.9106. Both
were determined
using Downhill Simplex method for a pupil size of 5.6 mm and vergence of 3D
with 0.1D step,
without residual accommodation. The left panel shows an optimal shape for 6
normal polynomial
terms and the right panel shows an optimal shape with 4 EPTP terms. It has
been found that
polynomials up to the 8th power (4 EPTP terms) appear to give highly
satisfactory results.
[0161] Fig. 8B shows another comparison of EPTP and non-EPTP expansions. The
left panel
shows an optimized shape based on an 8th order expansion (EPTP), whereas the
right panel shows
an optimized shape based on a 3rd order expansion (non-EPTP). In general,
shapes derived from
an EPTP have a smoother shape with a flat central zone. This flat central zone
can correspond to
good distance visual performance.
[0162] Another comparison of EPTP and non-EPTP expansions is provided in Fig.
8C, which
shows optimized (minimized) values with EPTP and non-EPTP expansion for a 4,
5, and 6 mm
pupil over a 3D vergence distance. In general, non-EPTP optimization gives a
slightly smaller
(more optimized) value than EPTP. Sixth-order EPTP appears to give the
smallest value for 4 mm
and 5 mm pupils and eighth-order EPTP appears to give the smallest value for a
6 mm pupil.
Third-order non-EPTP appears to give the smallest value for 4 mm and 5 mm
pupils and fourth-
order non-EPTP appears to give the smallest value for a 6mm pupil.
[0163] Using an even-power-term polynomial (EPTP) expansion can result in a
smoother shape
than a non-EPTP expansion. This smooth shape can be the minimal requirement
for good distance
vision. In general, 6th-order or 8th-order EPTP expansion and 3rd-order or 4th-
order non-EPTP
expansion result in good optimized value. Without residual accommodation,
larger pupils can be
more difficult to optimize than smaller pupils. This is shown, for example, in
Fig. 11A.
33
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0164] The optimized multi-focal shape appears to give much more balanced
results for the
correction of presbyopia than bi-focal and multi-focal shapes.
[0165] In addition to using a general polynomial expansion for the optimal
surface, it is also
possible to use other means of surface expansion. For example, Zernike
polynomial expansions
may be used. The following formula presents an example of a Zemike polynomial
expansion
W (r) =1c,Z,(r,19)
,=1
where radially symmetric terms such as Z4, Z12, and Z24 can be used, and c,
are free parameters.
[0166] Another way of surface expansion is by means of spectral expansion, or
Fourier
expansion. The following formula presents an example of a Fourier expansion.
W(r) = ciFi(r)
i=1
where c, are free parameters. Fourier expansion is based on the premise that
any surface can be
decomposed into a set of sinusoidal harmonics with different spatial
frequencies. It may not be
necessary to expand the surface to very high spatial frequencies.
[0167] Discrete surface, or discrete shape entirety, is another type of
expansion that can be used
in the present invention. Discrete surface can be represented by the following
formula
iW(r)= Wf ( =1,2,...,M; j=1,2,...,M)
i
where W,, are free parameters (M x M).
Inputting A Set Of Patient Parameters Into an Optimizer
[0168] The set of patient parameters can also be referred to as the set of
user input parameters.
The input parameters may provide certain patient characteristics, such as
pupil size and its
variations, desired power, and residual accommodation which can be modeled by
factors such as
gender, age, and race, or which can be measured by instruments.
[0169] Residual accommodation can be measured in diopters. Vergence can also
be measured in
diopters and typically is inversely related to distance, such that a distance
of infinity corresponds to
a vergence of zero. Similarly, a normal reading distance of 1/3 meters can
correspond to a
vergence of 3 diopters, and a farther distance of 10 meters can correspond to
0.1 diopters.
[0170] It can be useful to model the residual accommodation in the
optimization process. The
visual quality of the shape can be optimized given a certain set of conditions
such as vergence,
34
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
residual accommodation, and chromatic aberrations. However, even without a
direct correlation
between optical surface and the visual quality, it may be convenient to use
the minimum root-
mean-square (RMS) error to determine the accommodation during different visual
vergence. For
instance, if no aberrations are present, and there is 2D of residual
accommodation, such a patient
uses 0.5 D of residual accommodation when visualizing a target at 2 meters.
Relatedly, the patient
uses all 2D of residual accommodation to view a target at 0.5 meters. The
patient would have
difficulty viewing targets closer than 0.5 meters, as the residual
accommodation is exhausted and
no longer available. People with larger pupils or smaller residual
accommodation may be harder
to treat.
[0171] When aberrations or additional add-on shapes are present, the amount of
residual
accommodation for different visual vergence may vary. For example, in a
patient having 0.5D
residual accommodation, with an add-on shape of exactly 1D added to the eye,
the eye may not
need to accommodate until viewing a target at a distance of one meter. Here,
the 1D add-on can
cover the first diopter of visual vergence, either entirely or partially. At a
large distance, the visual
quality may be worse because the eye cannot accommodate in the reverse
direction. The
techniques of the present invention can be adapted to enhance an optimizer
value at low vergence
when residual accommodation is assumed.
[0172] When a more complicated add-on shape is used, one way to determine the
accommodation is to calculate the available residual accommodation which would
minimize the
overall RMS.
[0173] Shape optimization can be customized for a patient. The customization
can include the
patient's pupil sizes at different lighting and viewing conditions, such as
bright far viewing, bright
near viewing, dim far viewing, and dim near viewing. The optimization can also
be based on the
patient's residual accommodation, or predicted residual accommodation based on
the patient's age,
or the patient's vision preference due to for example, their employment or
other requirements.
That is to say, the customization can put more emphasis on far, near, or
intermediate viewing.
Similarly, the customization can put more emphasis on dim lighting condition,
bright lighting
condition or scotopic lighting condition. Further, the optimization can be
based on how long the
patient wishes to have the correction last. In many ways, presbyopia
correction can be a
management of compromise. If a patient needs to have excellent correction, he
or she might need
re-treatment after a couple of years as he or she gets older, when residual
accommodation
diminishes and/or the pupil size becomes smaller.
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
Inputting A Set Of Initial Conditions Into an Optimizer
[0174] The output result, or optical surface shape, can be sensitive to the
choice of the initial
condition. In the case of Downhill Simplex method, the initial condition can
be the initial N+1
vertices as well as the corresponding initial optimizer values for an N-
dimensional problem. In
other words, the conditions can be the initial vertices, as well as the value
associated with these
vertices, for N independent variables. In the case of the Direction Set
method, the initial condition
can be the initial N direction's unit vector and an initial point for an N-
dimensional problem.
[0175] When both or either the initial values for the polynomial coefficients
and the pupil ratio
are set low, the resulting actual numbers may often be low, especially for the
case of pupil ratio.
In one example, the initial condition is chosen to be 1.75 for all
coefficients and 0.26 for pupil
ratio. Figs. 9A-9D show a variety of shapes determined using different initial
conditions, as
calculated by the Downhill Simplex method. Pupil size of 5.6 mm and vergence
of 3D with 0.1D
step are assumed. Shape for Fig. 9A is 4.12r-0.235r2+0.08r3-
6.9r4+4.81r5+2.157r6; for Fig. 9B it is
2.6165r2+4.1865r4+6.9123r6-9.6363r8; for Fig. 9C it is 1.7926r+5.0812r2-
2.163r3-2.3766r4-
1.1226r51.6845r6; and for Fig. 9D it is ¨1.5178r2+7.2303r4-2.4842r6-
1.7458r8+1.8996r10.
[0176] For the initial conditions, totally random input and fixed ratios may
not necessarily help
the algorithm to converge to a global minimum or maximum.
[0177] Implementing An Optimizer To Establish A Customized Optical Shape For
The
Particular Patient Per The Goal function So As To Treat Or Mitigate A Vision
Condition In
The Particular Patient
[0178] The iterative optimization algorithm can be employed to calculate a
shape that optimizes
the optical quality for the particular patient. For example, in the case of
presbyopia the shape can
be calculated to optimize distance vision and near vision. In other words, the
corrective optical
surface shape corresponds to the set of output parameters provided by the
optimizer. The output
parameters can be the coefficients of polynomials describing the shape, as
well as the ratio of
diameter of the shape to that of the pupil diameter. These output parameters
can define the final
customized or optimized optical surface shape. This approach provides a
numerical way for
general optimization of the optical surface shape for correction or treatment
of a vision condition,
such as presbyopia. Whether it is for refractive surgery, contact lens,
spectacle lens, or intra-
ocular lens, the approach can be very beneficial. For presbyopes with
refractive error, the optimal
shape can be combined with the shape that corrects for the refractive error,
for example the
patient's measured wavefront error.
36
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0179] In order to model such deviation in practice, Gaussian distributed
noise can be added into
the shape so that when noise is present the stability of the algorithm can be
tested. For example,
Gaussian noise of standard deviation of 0.02 inn OPD can be introduced. This
corresponds to
nearly 0.06 inn in tissue depth in the case of laser surgery. This is larger
than the general RMS
threshold for the Variable Spot Scanning (VSS) algorithm for such a shape.
Fig. 10 illustrates a
comparison of the shapes calculated with a noise-free (dark) condition and
with a 0.02 inn
standard deviation of Gaussian random noise in OPD on the wavefront. The noise-
free case has an
optimizer value of 3.008 with 184 iterations and the noisy case has an
optimizer value of 2.9449
with 5000 iterations. Both use Downhill simplex method. Pupil size is 5 mm
with 3D vergence
and 0.1D step. Noise addition can also help to guarantee the stability of the
algorithm.
[0180] It is also possible to test how the convergence, optimizer value, and
shape work with
different input pupil sizes. An example of results from such a test is shown
in Table 1. For
smaller pupil sizes, the shape can cover the whole pupil. That is to say, the
shape can be larger
than the pupil size. Also, the depth may tend to become smaller with smaller
pupils.
Pupil # A B C D T
Value Depth
Iterations
6.0 234 -1.5688
12.0893 -0.5895 -2.6934 0.9866 2.6808 7.2881
5.8 316 -0.5212
4.4186 -0.8472 -0.0764 0.6870 2.8215 2.9980
5.6 152 -1.1003
8.2830 0.7305 -2.2140 0.9106 2.6580 5.7356
5.4 274 -0.5918
5.0881 1.2448 -1.1930 0.9124 2.7539 4.5651
5.2 269 -1.4101
5.3067 -0.4326 -0.4379 0.7944 2.7979 3.1210
5.0 186 0.4079
2.2298 0.0598 1.1958 0.9446 3.0080 3.8933
4.8 531 -3.4870
54.9625 48.5083 -125.31 1.8427 2.6772 4.0692
4.6 492 -1.3517
8.5336 -4.8138 1.6981 0.999 2.5871 4.1223
4.4 422 -2.1972
17.2673 32.1306 -44.903 1.5095 2.6924 3.4652
4.2 163 -0.8345
4.2663 4.3575 -3.5136 1.1093 2.7196 2.9770
4.0 545 -4.8205
29.1525 7.9952 -23.086 1.5984 2.6822 2.7003
3.8 333 0.1519
0.6105 2.5097 -1.6318 0.7765 3.0533 1.6403
3.6 177 -1.0422
1.4185 2.2061 -0.9600 0.9736 2.7533 1.7636
3.4 230 -3.6844
19.0878 4.2289 5.3957 1.6909 2.7202 1.4760
3.2 219 -1.2266
1.9391 0.8145 0.2914 1.0989 3.0486 1.0858
3.0 287 3.3482 -
2.5793 0.8977 -0.3937 0.9941 2.9061 1.3286
2.8 257 -0.2052
0.2657 0.0451 0.2494 0.7920 2.8933 0.3890
37
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
Pupil # A B C D T
Value Depth
Iterations
2.6 136 -0.6749
1.8074 0.3418 -0.3918 1.0637 2.7377 0.8731
2.4 332 -2.8455
16.408 -13.119 0.9270 1.5988 3.0920 0.7653
2.2 239 -2.6435
2.2329 1.9556 -1.7776 0.8557 3.1667 0.6329
2.0 303 -0.6398
0.9010 0.5835 -0.3601 0.9527 3.9384 0.5827
Table 1. Shapes for pupil dependency with 3D vergence and 0.1D step.
[0181] As determined by the approach of the present invention, one desirable
optical surface
shape has a central un-ablated zone and an outside zone that provides improved
near vision or
reading capability. Based on the example shown in Fig. 7, the central flat
zone can be about 1.96
mm in diameter. Because the healing effect may reduce the central zone, the
planned flat ablation
may need to go beyond 2 mm in order to get a healed flat zone of about 1.96
mm. This can be for
a pupil size of about 5.6 mm (natural size). The present invention can also
consider practical pupil
dependency in the approach. In one example of the present invention, the
optical zone can go to
about 0.91 times the size of the pupil size, which is about 5.1 mm. Further,
the present invention
may also incorporate a transition zone such as the VISX standard transition
zone technique, as
used in variable spot scanning (VSS). What is more, the present invention can
also provide a clear
mathematical description for the optical surface shape outside of the un-
ablated zone.
[0182] Relatedly, Fig. 11C illustrates that there can be a dependency between
optimizer value
and pupil size. Fig. 11C also shows a preferred optimizer value (optimal). An
optimizer value can
be a value of the goal function after it is optimized. Theoretically, this
value should not be smaller
than unity. An optimization, or minimization, algorithm can be used to find
values of free
parameters such that the optimizer value is as close to unity as possible.
[0183] The present invention can incorporate varying pupil sizes, although
presbyopes may tend
to have smaller pupil size variation. Because an optimal shape for a fixed
pupil size may no longer
be optimized if the pupil size changes, the present invention can provide
approaches that can allow
for pupil size variations. The final optical surface shape can be one that
gives an optimal optical
quality over a certain vergence range when the pupil size varies over a range.
[0184] To demonstrate how effective a solution is in terms of optical metrics,
the MTF can be
shown at different spatial frequencies, as illustrated in Figs. 11A-C, which
provides optimizer
values for various corrections. Apparently the optimal curve gives the minimum
(optimized) value
for all pupil sizes. Eyes with larger pupils can be more difficult to
optimize. What is more,
38
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
carefully designed multi-focal correction can be close to optimal, as further
illustrated in Figs.
11A-C. That is, the optimizer value for the multi-focal correction can be
close to that of the
optimized correction, hence the results are quite similar. This outcome is
also illustrated in Fig.
13. The lower regression line in Fig. 11C can set the practical limit for the
optimizer value.
[0185] In another approach, to demonstrate how effective a solution is in
terms of optical
metrics, the compound MTF can be plotted, as shown in Figs. 9A-B. Here, the
compound MTF
for various treatments for a 5 mm pupil over a 3D vergence is plotted. It can
be beneficial to
optimally balance the level of compound MTF at every vergence distance or over
the desired
vergence. Fig. 9C shows a comparison of bi-focal and optimal corrections, with
a simulated eye
chart seen at different target distances, assuming a 5mm pupil with no
accommodation. The eye
chart has 20/100, 20/80, 20/60, 20/40, and 20/20 lines, respectively.
[0186] Fig. 10 is a simulated eye chart seen at different target distances,
and compares an
optimized case (bottom) to no correction (top line); reading glasses (second
line); bi-focal lenses
(inner half for reading and outer half for distance, third line); and multi-
focal lenses (pupil center
for reading with maximum power and pupil periphery for distance with zero
power and linear
power change in between, four line). The effects of the optimization can be
clearly seen by the
comparison. No accommodation or refractive error is assumed in any of the
cases. The eye chart
has 20/100, 20/80, 20/60, 20/40, and 20/20 lines.
[0187] Using the above approaches, it is possible to obtain a shape that is
not only larger than
the pupil size, but that can also be practically implemented. Often, only the
portion of the shape
inside the pupil may be evaluated for optical quality, although this is not a
requirement. For
example, the entire zone over the pupil can remain un-ablated, but there may
be a zone outside the
pupil that is ablated. In this way, distance vision is not affected, but for
near vision, there can be
an advantage from light coming outside of the pupil due to greatly deformed
periphery. A goal
function based on geometrical optics, or ray tracing, can be useful to
determine such shapes.
[0188] Residual accommodation can also affect the optimization result, because
it can remove
some of the ripples on the combined wavefront at any vergence.
[0189] The approaches of the present invention can be implemented on a variety
of computer
systems, including those with a 200MHz CPU with 64MB memory, and typically
will be coded in
a computer language such as C or C++. Simulations have successfully been run
on a laptop
computer with a 1.2GHz CPU with 256 MB memory. The techniques of the present
invention can
also be implemented on faster and more robust computer systems.
39
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0190] The present invention includes software that implements the optimizer
for practical
applications in a clinical setting. The optimizer will often comprise an
optimizer program code
embodied in a machine-readable medium, and may optionally comprise a software
module, and/or
a combination of software and hardware. As shown in Figs. 14-16, the software
interface can
comprise two primary panels: the parameter panel and the display panel. The
parameter panel can
be split into two sub-panels: optimization and verification. The display panel
can also be split into
two sub-panels: graph panel and image panel. The software can also include a
menu bar, a tool
bar, and a status bar. In the tool bar, small icons can be used for easy
access of actions.
[0191] The optimization sub-panel can include a number of parameter units. For
example, a first
parameter unit can be the pupil information group. In the examples shown in
Figs. 14-16, the user
or operator can give four different pupil sizes for a specific eye. More
particularly, the pupil
information group includes the pupil size in (a) bright distance viewing
condition, (b) bright near
viewing condition (e.g. reading), (c) dim light distance viewing condition,
and (d) dim light near
viewing condition (e.g. reading). These different pupil sizes can be used in
the optimization
process.
[0192] A second parameter unit in the optimization sub-panel can be the
display group. In the
examples shown in Figs. 14-16, the user or operator has three different
choices for the display,
including (a) none, (b) shape, and (c) metric. The display group can provide
instruction to the
software regarding what kind of display is desired for each iteration. For
instance, none can mean
no display, shape can mean displaying the current shape, and metric can mean
displaying the
current optical metric curve over the desired vergence for this current shape.
The choices can be
changed during the optimization procedure, and in this sense it is
interactive.
[0193] A third parameter unit in the optimization sub-panel can be the optical
metric group. In
the examples shown in Figs. 14-16, the user has five different choices for the
metric, including (a)
Strehl ratio, (b) MTF at a desired spatial frequency, (c) encircled energy at
a desired field of view,
(d) compound MTF (CMTF) with a set of specific combinations, which could be
any number of
MTF curves at different spatial frequencies, and when the "auto" check box is
checked, it can use
a default CMTF with three frequencies, such as, for example: 10, 20 and 30
cycles/degree, and (e)
the MTF volume up to a specific spatial frequency. 25% CMTF over the vergence
appears to be
an example of a good target value for optimization.
[0194] A fourth parameter unit in the optimization sub-panel can be the
optimization algorithm
group. In the examples shown in Figs. 14-16, the user has three different
choices for the
optimization algorithm employed by the optimizer, including (a) the Direction
Set (Powell' s)
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
method, (b) the Downhill Simplex method, and (c) the Simulated Annealing
method. The
optimizer can employ a standard or derived algorithm for function optimization
(minimization or
maximization). It can be a multi-dimensional, non-linear, and iterative
algorithm.
[0195] A number of other parameters can be included in the optimization sub-
panel. As shown
in Figs. 14-16, these other parameters can be implemented separately
(optionally as a ComboBox)
with a number of choices for each. These can include parameters such as (a)
the number of terms
of the polynomial expansion, (b) the frame size, (c) the PSF type
(monochromatic, RGB, or
polychromatic), (d) whether the shape is EPTP or non-EPTP, (e) the vergence
requirement, (f) the
vergence step, and (g) the residual accommodation. The software can include a
StringGrid table
that displays the polynomial coefficients, the PAR value, the optimizer value,
as well as the current
number of iterations. These numbers can be updated every iteration.
[0196] The verification sub-panel can include a number of parameter units. For
example, a first
parameter unit can be the "which" group. In the examples shown in Figs. 14-16,
the operator can
use this group to select whether to use built-in eye chart letters, or an
entire eye chart or a scene. A
second parameter unit in the verification sub-panel can be the left image
group. The user can
make a selection in the left image group from PSF and imported scene. A third
parameter unit is
the right image group, wherein the user can make a selection from imported
scene, and blur at
near. The two image display groups are for the left and right subpanels in the
image subpanel.
[0197] As further illustrated in Figs. 14-16, the ComboBox for letter can
provide a list of
different eye chart letters, and the VA ComboBox can provide the expected
visual acuity, from
20/12 to 20/250. The Contrast ComboBox can provide a list of contrast
sensitivity selections,
from 100% to 1%. Two check box can also be included. The Add check box, once
checked, adds
the presbyopia to the simulated eye. The Test check box, when checked,
performs the distance
(zero vergence). At the bottom, there is a slider with which all the saved
images (e.g. PSF and
convolved images) can be reviewed.
[0198] There are many factors that can affect the pupil size, and these
factors can be considered
optimization approaches of the present invention. For example, the shape can
be customized for
various lighting and accommodation conditions. As shown in Fig. 17, and
further discussed in
Table 2, pupil size can change with lighting conditions. Each of the
presbyopia-mitigating and/or
treating methods, devices, and systems described herein may take advantage of
these variations in
pupil size. A pupil size of a particular patient will often be measured, and
multiple pupil sizes
under different viewing conditions may be input for these techniques.
41
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
Table 2
dim bright
distance 5 mm 3.5 mm
near 4 mm 2.5 mm
[0199] A patient can also have a task-related vision preference that
correlates with lighting
conditions, such as those described in Table 3, and the customization can be
based upon these
task-related preferences.
Table 3
cd/m2 lighting condition
30 subdued indoor lighting
60 display-only workplaces
120 typical office
240 bright indoor office
480 very bright; precision indoor tasks
960 usual indoors
1920 bright afternoon
[0200] Fig. 18 illustrates that pupil size can change with accommodation, and
Fig. 19 illustrates
a comparison of corrections by providing optimizer values for various
accommodations. With 3 or
more diopters of residual accommodation, the optimizer value can achieve a
limit of about 1.0,
regardless of the pupil size. Typically, a larger amount of residual
accommodation can correspond
to a smaller optimizer value after optimization. The limit line can correspond
to an optimizer
value of about 5Ø In other words, an optimizer value of about 5.0 can be
viewed as a good
practical limit. Either there can be a smaller pupil, or a larger amount of
residual accommodation,
in order to optimize such that all vergence distances have good visual
performance.
[0201] Figs. 20 and 21 show optimizations under various accommodation
conditions. Figs. 21A
and 21B show CMTF and optimizer values when pupil size changes and Residual
Accommodation
(RA) are modeled. Fig. 21C shows simulated eye charts seen at different target
distances after
optimization, all assuming a 5mm maximum pupil size. Each eye chart has
20/100, 20/80, 20/60,
20/40, and 20/20 lines. The top line simulates no accommodation and no pupil
size changes. The
middle line assumes no accommodation but the pupil size changes from 5mm (dim
distance) to
2.5mm (bright near). In the bottom line, the simulation assumes 1D
accommodation with pupil
size changes from 5mm (dim distance) to 2.5mm (bright near).
[0202] Fig. 22 shows CMTF values for various corrections. A 5mm pupil eye is
assumed, along
with a smallest pupil size of 2.5mm (bright light reading condition) and a 1D
residual
42
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
accommodation. Fig. 23 compares bi-focal, optimal, and multi-focal
corrections, under the
assumption of a one diopter residual accommodation. These simulated eye charts
are seen at
different target distances after optimization. 1D accommodation and a 5mm
pupil changes from
5mm (dim distance) to 2.5mm (bright near) are assumed. The eye chart has
20/100, 20/80, 20/60,
20/40, and 20/20 lines, respectively. Fig. 24 illustrates a simulated eye
chart seen at different
target distances. The data in this figure based on the assumption that the
pupil size decreases from
5 mm to 2.5 mm, and there is a 1 diopter residual accommodation in all cases.
[0203] The customized shape methods and systems of the present invention can
be used in
conjunction with other optical treatment approaches. For example, co-pending
U.S. provisional
patent application number 60/431,634, filed December 6, 2002 (Attorney Docket
No. 018158-
022200US) and co-pending U.S. provisional patent application number 60/468,387
filed May 5,
2003 (Attorney Docket No. 018158-022300US), the disclosures of which are
hereby incorporated
by reference for all purposes, describe an approach to defining a prescription
shape for treating a
vision condition in a particular patient. The approach involves determining a
prescriptive
refractive shape configured to treat the vision condition, the prescriptive
shape including an inner
or central "add" region and an outer region. The approach also includes
determining a pupil
diameter of the particular patient, and defining a prescription shape
comprising a central portion,
the central portion having a dimension based on the pupil diameter, the inner
region of the
prescriptive refractive shape, and an attribute of at least one eye previously
treated with the
prescriptive refractive shape.
[0204] Accordingly, the present invention can include a method for determining
a customized
shape that includes a scaled central portion as described above, the
customized shape giving results
at least as good or better than previously known methods.
[0205] Systems
[0206] The present invention also provides systems for providing practical
customized or
optimized prescription shapes that mitigate or treat vision conditions such as
presbyopia in
particular patients. The systems can be configured in accordance with any of
the above described
methods and principles.
[0207] For example, as shown in Fig. 25, a system 100 can be used for
reprofiling a surface of a
cornea of an eye 150 of a particular patient from a first shape to a second
shape having correctively
improved optical properties. System 100 can comprise an input 110 that accepts
a set of patient
parameters, a module 120 that determines an optical surface shape for the
particular patient based
43
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
on the set of patient parameters, using a goal function appropriate for a
vision condition of an eye,
a processor 130 that generates an ablation profile, and a laser system 140
that directs laser energy
onto the cornea according to the ablation profile so as to reprofile a surface
of the cornea from the
first shape to the second shape, wherein the second shape corresponds to the
prescription shape.
[0208] Referring to Fig. 26A, the present invention will often take advantage
of the fact that the
eye changes in two different ways with changes in viewing distance: the lens
changes in shape so
as to provide accommodation, and the pupil size simultaneously varies.
Accommodation and
pupillary constriction work in unison in normal healthy eyes when shifting
from a far to a near
viewing distance, and a fairly linear relation may exist between at least a
portion of the
overlapping constriction and accommodation ranges, but the effect may vary
significantly among
subjects (from 0.1 to 1.1 mm per diopter). Moreover, when the stimulus for
accommodation is
increased beyond the eye's ability to change its refraction, the relationship
between
accommodation of the lens and pupillary constriction may be curvilinear as
shown.
[0209] While they work in unison, pupillary constriction and accommodation are
not necessarily
linked. These two functions may proceed independently, and may even work in
opposite
directions, particularly when the patient is simultaneously subjected to large
variations in light
intensity with changes in viewing distance. Nonetheless, prescriptions for
presbyopia can take
advantage of the correlation between pupil dimension and viewing distance for
a particular patient.
The effective time span for a presbyopia-mitigating prescription may also be
extended by
accounting for gradual changes in pupil dimension over time (such as the
gradual shrinkage of the
pupil as one ages) with the concurrent gradual decrease in the accommodation.
Details regarding
constriction of the pupil were published in a book entitled The Pupil by Irene
E. Loewenfeld (Iowa
State University Press, 1993).
[0210] Referring now to Fig. 26B and 26C, if we assume that we can tailor a
beneficial overall
optical power for the eye as it changes to different pupil sizes, we may first
want to identify a
relationship between this desired optical power and pupil size. To determine
what powers would
be desirable for a particular patient at different viewing conditions, we
might measure both the
manifest sphere and corresponding pupil sizes of that patient at a variety of
different viewing
conditions. The manifest sphere may then be used as our desired or effective
power to be used for
treating presbyopia, as detailed below. The desired optical power might also
be determined from
the measured manifest, for example, with desired power being a function of the
manifest to adjust
for residual accommodation and/or anticipated aging effects or the like. In
either case, these
patient-specific measurements can be the basis for determining desired powers
for associated pupil
44
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
sizes of that patient, such as at the four points illustrated in Fig. 26B.
Fewer or more points might
also be used.
[0211] Alternatively, manifest sphere and pupil size for a population of
different patients who
have been successfully treated with a given presbyopia prescriptive shape may
be plotted, and a
correlation derived from this empirical data, as schematically illustrated in
Fig. 26C. Still further
approaches may be employed, including combinations where a population of
patients having
differing pupil sizes are used to derive an initial correlation, which is
subsequently refined with
multiple measurements from at least one patient (and often a plurality of
patients). Regardless, the
relationship between our desired optical power and the pupil size can be
determined. As will be
clear from the detailed description below, constriction of the pupil at
differing viewing distances
then allows the overall power of the eye to be altered by the pupillary
constriction, despite a loss in
the flexibility of the lens. For example, we can employ a peripheral portion
of the ocular system
having a different power than a central portion. By understanding the
variations of these often
aspherical optical systems with changing pupil sizes, we can provide good
optical performance
throughout a range of viewing distances.
[0212] The following description will first provide techniques and devices for
iteratively
optimizing refraction for treatment of presbyopia. This is followed by a brief
review of an
exemplary initial laser ablation shape for mitigation of presbyopia, which is
in turn followed by an
explanation of techniques for optimizing that shape (or other shapes), often
using empirical and/or
patient-specific information to scale the shape. Generalized analytical and
numerical techniques
for determining or selecting appropriate presbyopia mitigating prescription
shapes will then be
provided.
[0213] Defining A Scaled Prescription shape For A Vision Condition
[0214] Determining a prescriptive prescription shape
[0215] Certain prescriptive refractive shapes are effective in treating vision
conditions, and it is
possible to provide an efficient prescription shape by scaling a shape to the
particular patient being
treated. Optical shapes can be scaled based on data collected from subjects
previously treated with
a uniform prescriptive optical shape, such as measured manifest powers for
different pupil sizes.
Shapes may also be scaled based on the desired overall optical power of the
eye under differing
viewing conditions.
[0216] It is useful to select or construct an initial prescriptive refractive
shape appropriate for the
vision condition. For example, prescriptive treatment shapes such as those
shown in Fig. 28 have
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
been found to provide a range of good focus to the eye so as to mitigate
presbyopia. This
particular prescriptive shape is the sum of two component shapes: a base curve
treatment defining
an outer region having a diameter of about 6.0 mm, and a refractive add
defining an inner region
having a diameter of about 2.5 mm. Prescriptive shapes such as this can
provide a spherical power
add ranging from between about 1.0 diopters to about 4.0 diopters at the inner
region. Further, the
spherical power add can be about 3.1 diopters. Combining the inner and outer
regions, the overall
prescriptive refractive shape can be aspheric. It is appreciated, however,
that the dimensions and
properties of a prescriptive shape can vary depending on the intended purpose
of the shape.
[0217] Treatment of presbyopia often involves broadening the focus range of
the eye. Referring
to Fig. 29, in an emmetropic eye a focal length of the optical system results
in a point of focus 10
that produces a sharp image. At this point, the refractive power of the cornea
and lens is matched
to the length of the eye. Consequently, light rays 20 entering the eye
converge on the retina 30. If
there is a difference between the refractive power and the length of the eye,
however, the light rays
can converge at a point 40 in front of or behind the retina, and the image
formed on the retina can
be out of focus. If this discrepancy is small enough to be unnoticed, it is
still within the focus
range 50 or depth of focus. In other words, the image can be focused within a
certain range either
in front of or in back of the retina, yet still be perceived as clear and
sharp.
[0218] As shown in Fig. 30, when an object is at a far distance 60 from the
eye, the light rays 20
converge on the retina 30, at focal point 10. When the object is moved to a
near distance 70, the
light rays 20' converge at a focal point 80 beyond the retina. Because the
image is outside of the
depth of focus 50, the image is perceived to be blurred. Through the process
of accommodation,
the lens changes shape to increase the power of the eye. The power increase
brings the focal point
80 back toward the retina as the eye attempts to reduce the blur.
[0219] In the presbyopic eye the accommodative mechanism may not work
sufficiently, and the
eye may not be able to bring the focal point to the retina 30 or even within
the range of focus 50.
In these circumstances, it is desirable to have an optical system having a
broadened focus range
50'. One way to achieve this is by providing an optical system with an
aspheric shape. The
aspheric shape, for example, can be ablated on a surface of the eye, the
surface often comprising a
stromal surface formed or exposed by displacing or removing at least a portion
of a corneal
epithelium, or a flap comprising corneal epithelium, Bowman's membrane, and
stroma. Relatedly,
the shape can be provided by a correcting lens. In some optical systems, only
a portion of the
shape may be aspheric. With an aspheric shape, there is not a single excellent
point of focus.
Instead, there is greater range of good focus. The single best focus acuity is
compromised, in order
46
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
to extend the range of focus. By extending the range of focus 50 to a
broadened range of focus
50', there is an improvement in the ability to see both distant and near
objects without the need of
3D or more in residual accommodation.
[0220] Without being bound by any particular theory, it is believed that the
power add of the
inner region depicted in Fig. 28 provides a myopic effect to aid near vision
by bringing the near
vision focus closer to the retina, while the outer region remains unaltered
for distance vision. In
this sense the application of this prescriptive shape is bifocal, with the
inner region being myopic
relative to the outer region. Put another way, the eye can use the inner
region for near vision, and
can use the whole region for distance vision.
[0221] In a laser ablation treatment, the prescriptive refractive ablation
shape can have fairly
abrupt changes, but post ablation topographies may show that healing of the
eye can smooth the
transitions. The shape can be applied in addition to any additional required
refractive correction
by superimposing the shape on a refractive corrective ablation shape. Examples
of such
procedures are discussed in co-pending U.S. patent application number
09/805,737, filed March
13, 2001, the disclosure of which is herein incorporated by reference for all
purposes.
[0222] Alternative presbyopia shapes may also be scaled using the techniques
described herein,
optionally in combination with other patient customization modifications, as
can be understood
with reference to U.S. Provisional Patent Application Nos. 60/468,387 filed
May 5, 2003,
60/431,634, filed December 6, 2002, and 60/468,303, filed May 5, 2003, the
disclosures of which
are herein incorporated by reference for all purposes. Alternative presbyopia
shapes may include
concentric add powers along a peripheral or outer portion of the pupil, along
an intermediate
region between inner and outer regions, along intermittent angular bands, or
the like; asymmetric
(often upper or lower) add regions, concentric or asymmetric subtrace or
aspheric regions, and the
like. The present application also provides additional customized refractive
shapes that may be
used to treat presbyopia.
[0223] Determining a pupil diameter of the particular patient
[0224] When scaling a refractive shape to treat a particular patient, it is
helpful to determine the
pupil diameter of the particular patient to be treated. Several methods may be
used to measure the
pupil diameter, including image analysis techniques and wavefront measurements
such as
Wavescan (AMO Manufacturing USA, LLC in Milpitas, CA) wavefront measurements.
The size
of the pupil can play a role in determining the amount of light that enters
the eye, and can also
have an effect on the quality of the light entering the eye. When the pupil is
very constricted, a
relatively small percentage of the total light falling on the cornea may
actually be allowed into the
47
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
eye. In contrast, when the pupil is more dilated, the light allowed into the
eye may correspond to a
greater area of the cornea. Relatedly, the central portions of the cornea have
a more dominant
effect on the light entering the eye than do the peripheral portions of the
cornea.
[0225] Pupil size can have an effect on light quality entering the eye. When
the pupil size is
smaller, the amount of light passing through the central portion of the cornea
is a higher
percentage of the total light entering the eye. When the pupil size is larger,
however, the amount of
light passing through the central portion of the cornea is a lower percentage
of the total light
entering the eye. Because the central portion of the cornea and the peripheral
portion of the cornea
can differ in their refractive properties, the quality of the refracted light
entering a small pupil can
differ from that entering a large pupil. As will be further discussed below,
eyes with different
pupil sizes may require differently scaled refractive treatment shapes.
[0226] An inner region of the prescriptive refractive shape
[0227] Experimental data from previously treated eyes can provide useful
information for
scaling a refractive treatment shape for a particular patient. For example, a
refractive shape for a
particular patient can be scaled based on certain characteristics or
dimensions of the shape used to
treat the eyes of the subjects. One useful dimension of the above-described
presbyopic
prescriptive shape is a size or diameter of inner region or refractive add. It
is possible to scale a
treatment shape for a particular patient based on the diameter of the
refractive add of the
prescriptive shape. Alternative techniques might scale a power of an inner,
outer, or intermediate
region, a size of an outer or intermediate region, or the like.
[0228] If the refractive add diameter is small, it can occupy a smaller
percentage of the total
refractive shape over the pupil. Conversely, if the refractive add diameter is
large, it can occupy a
greater percentage of the total refractive shape over the pupil. In the latter
case, because the area
of the periphery is relatively smaller, the distance power is diminished. In
other words, the area of
the add is taking up more of the total refractive shaped used for distance
vision.
[0229] An attribute of a set of eyes previously treated with the prescriptive
refractive shape
[0230] As noted above, experimental data from previous prescriptive eye
treatments can be
useful in scaling a treatment for a particular individual. When scaling a
presbyopia treatment
shape, it is helpful to identify a pupil diameter measure from among a set of
previously treated
eyes having a fixed treatment size that corresponds to both good distance and
near sight. It is
possible to use acuity and power measurements from the set of treated eyes to
determine such a
48
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
pupil diameter. The fixed treatment size (e.g. 2.5 mm inner region) can then
be said to be
appropriate for this identified pupil diameter.
[0231] Figs. 31 and 32 illustrate the effect that pupil size can have on
distance acuity and near
acuity in subjects treated with a prescriptive refractive shape, for example a
shape having a 2.5 mm
central add zone of -2.3 diopters. Referring to Fig. 31, pupil size values
were obtained from a
group of subjects as they gazed into infinity under mesopic or dim light
conditions. The 6-month
uncorrected distance acuity values were obtained from the same group of
subjects under photopic
conditions. Referring to Fig. 32, pupil size values were obtained from a group
of subjects as they
gazed at a near object under mesopic or dim light conditions. The 6-month
uncorrected near
acuity values were obtained from the same group of subjects under photopic
conditions.
[0232] One way to determine an optimal pupil diameter measure is by
superimposing a near
acuity graph over a distance acuity graph, and ascertaining the pupil diameter
that corresponds to
the intersection of the lines.
[0233] Another way to determine a pupil diameter that corresponds to both good
distance and
near acuity is to define each of the slopes mathematically:
Near acuity = -2.103 + 0.37879 * Pupil size (Dim) (Fig. 27)
Distance acuity = 0.40001 - 0.0677 * Pupil size (Dim) (Fig. 26)
[0234] By setting the two equations from the graphs equal, it is possible to
solve for the
intersection point.
-2.103 + 0.37879 * Pupil size (Dim)= 0.40001 - 0.0677 * Pupil size (Dim)
Pupil size (Dim)=2.4/0.45= 5.33 mm
[0235] An optimum overlap can occur in a range from between about 4.0 mm to
about 6.0 mm.
Further, an optimum overlap can occur in a range from between about 5.0 mm to
about 5.7 mm.
These measurements may correspond to a pupil diameter measure from the set of
previously
treated eyes that corresponds to both good distance and near vision when the
diameter of the
central add region is 2.5 mm.
[0236] Defining a refractive shape for treating a particular patient acuity
as a function of pupil size
[0237] The present invention provides methods and systems for defining a
prescription for
treating a vision condition in a particular patient, with the prescription
optionally comprising a
refractive shape. Such a method can be based on the following features: (a) a
prescriptive
refractive shape configured to treat the vision condition, including an inner
region thereof; (b) a
49
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
pupil diameter of the particular patient, and (c) an attribute of a set of
eyes previously treated with
the prescriptive shape.
[0238] For example, the prescriptive shape can be the shape described in Fig.
28. The inner
region of the shape can be a refractive add, having a diameter of 2.5 mm. For
illustrative purposes,
a pupil diameter of the particular patient of 7 mm is assumed. The attribute
of a set of previously
treated eyes can be the pupil diameter of the eyes that corresponds to both
good distance and near
vision, such as the exemplary 5.3 mm treated pupil diameter shown in Figs. 31
and 32. Thus, a
ratio of the prescriptive refractive add to treated pupil (PAR) can be
expressed as 2.5/5.3.
[0239] The PAR can be used in conjunction with the pupil diameter of the
particular patient to
scale the refractive shape. For example, a central portion of the scaled
refractive shape can be
calculated as follows.
central portion diameter = PAR * pupil diameter of particular patient
[0240] Given the example above, the diameter of a central portion of the
scaled refractive shape
for treating the particular patient is:
(2.5/5.3)*7 mm = 3.3 mm
[0241] In this example, this scaled central portion can correspond to the
diameter of the
refractive add of the defined refractive shape. It should be appreciated that
the refractive shape
and the central portion of the refractive shape can alternately be spheric or
aspheric. For example,
the refractive shape can be aspherical, and the central portion of the
refractive shape can be
aspherical; the refractive shape can be spherical and the central portion of
the refractive shape can
be spherical; the refractive shape can be aspherical, and the central portion
of the refractive shape
can be spherical; or the refractive shape can be spherical, and the central
portion of the refractive
shape can be aspherical.
[0242] As shown above, the PAR can be about 2.5/5.3, or 0.47. It will be
appreciated that the
PAR can vary. For example, the PAR can range from between about 0.35 and 0.55.
In some
embodiments, the PAR may range from about 0.2 to about 0.8. Optionally, the
PAR can range
from about 0.4 to about 0.5. Further, the PAR can range from about 0.43 to
about 0.46. It will
also be appreciated that the ratios discussed herein can be based on area
ratios or on diameter
ratios. It should be assumed that when diameter ratios are discussed, that
discussion also
contemplates area ratios.
[0243] Power as a function of pupil size
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0244] In another example, the attribute of a set of previously treated eyes
can be the pupil
diameter of the eyes that correspond to both good distance and near values for
spherical manifest.
A group of individuals with varying pupil sizes were treated with the same
prescriptive refractive
shape, the shape having a constant presbyopic refractive add diameter of
approximately 2.5 mm.
Pupil sizes were obtained on a Wavescan device. The Spherical Manifest at 6
months post-
treatment is shown as a function of the pupil size in Fig. 33. Here, the
spherical manifest
represents the effective distance power as the result from the total
prescriptive shape, including the
inner region and outer regions of the shape.
[0245] As Fig. 33 illustrates, for a given prescriptive treatment shape, the
effect that the shape
has on the individual's manifest can depend on the individual's pupil
diameter. Depending on the
pupil size of the treated subject, the refractive add will have different
relative contribution to the
power. And due to the varying pupil sizes, the prescriptive refractive add to
treated pupil ratio
(PAR) may not be constant. Thus, with the same prescriptive treatment, the
effective power can
vary among different patients. In a simplified model, the power change from
the central portion of
the treated eye to the periphery can be assumed to be linear. This
simplification can be justified by
the data. The change in power can be represented by the following formula,
expressed in units of
diopters.
MRS (Effective Distance Power) = -2.87 + 0.42 * Pupil size (Dim) kliopters]
[0246] The rate change in effective power is 0.42D per mm for distance vision.
It has been
shown that the pupil diameter can change at a rate of approximately 0.45D per
mm. The add
power is -2.87 diopters.
[0247] Without being bound by any particular theory, it is thought that due to
the asphericity of
the central add, there can be a linear relationship between the effective
distance power and the
pupil diameter. Accordingly, is it possible to characterize the ratio of
effective distance power
versus pupil diameter with the following linear core equation, where Co and A
are constants.
Equation A: Effective Distance Power = Co + A(pupil_diameter)
[0248] In individuals having smaller pupil diameters, the contribution of the
outer region of the
prescriptive shape is diminished; the manifest refraction is more myopic and
the effective power is
smaller. And whereas a lower MRS value can correspond to a more myopic
refraction, a higher
MRS value can correspond to a less myopic refraction. The manifest refraction,
which can be
expressed in terms of power, is often proportional to distance vision, which
can be expressed in
terms of acuity or logarithm of the minimum of angle of resolution (logMAR).
51
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0249] As discussed above, a PAR can be determined based on acuity
measurements as a
function of pupil size. In an analogous manner, it is possible to determine a
PAR based on power
measurements as a function of pupil size.
[0250] Skewing
[0251] The Effective Distance Power Equation A above represents one approach
to finding a
good approximation to customize the refractive shape size. In sum, the
intersection of a distance
version of the equation and a near version of the equation is solved to
determine a pupil diameter
measure, which forms the denominator for the PAR (prescriptive shape add
diameter/pupil
diameter of treated eye). By adjusting the PAR, it is possible to adjust the
shape to achieve
emmetropia or other refractive states.
[0252] Altering the size of the prescriptive shape add
[0253] Referring to Fig. 33, a treated pupil diameter of about 5.4 mm has a
spherical manifest of
about -0.6 diopters. If the size of the prescriptive shape add is made bigger,
the line can be shifted
downward. Consequently, the effect in a particular patient treated with the
scaled refractive shape
would be a more myopic spherical manifest of -2.0, for example. On the other
hand, if the size of
the add is made smaller, the line can be shifted upward, and the effect would
be a spherical
manifest of -0.2, for example. As the diameter of the add decreases, the
manifest of the particular
patient treated with the scaled refractive shape becomes more skewed to better
distance sight. As
the diameter of the add increases, the manifest becomes more skewed to better
near sight.
[0254] Fixing the PAR
[0255] It is possible to set the near manifest for all patients by fixing the
PAR. Referring to the
example of Figs. 31 and 32 (where the Equation A intersection is about 5.3
mm), a ratio of 2.5/5.3
mm can rotate these near and distance lines toward horizontal, about the 5.3
mm point. In other
words, an analysis of particular patients treated with a PAR of 2.5/5.3 is
expected to result in
manifest versus pupil size plots having lines that are more horizontally
oriented. Thus each patient
would be expected to have similar near manifest. Alternatively, it is possible
to choose a different
point of rotation to optimize distance manifest over near manifest, or vice
versa. For example, by
choosing a 5.0 mm point for rotation, better near manifest can be provided at
the expense of the
distance manifest.
[0256] When comparing the graphs of Figs. 31 and 32 the distance acuity and
near acuity slopes
can vary. As shown in these figures, near vision changes at a slightly higher
rate than distance
vision. In other words, near vision appears to be more sensitive to changes in
pupil diameter than
52
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
distance vision. An adjustment was made to near measurements in Fig. 32 to
offset a distance
correction used during the measurement.
[0257] Non-linear models
[0258] The effective distance power versus pupil diameter can also be
expressed by the
following non-linear equation.
Equation B: Power = Co + A(pupil_diameter) + B(pupil_diameter)2 +
C(pupil_diameter)3 + ...
[0259] where Co, A, B, and C are constants. This equation is only one of many
that can be used
to model the desired relationship. Similar non-linear equations can be used to
model desired
effective power, as discussed below. Also, both linear and non-linear
equations can be used to
model target manifest, as discussed below.
[0260] Target manifest (acuity as a function of power)
[0261] The target manifest or desired power at a particular viewing distance
may or may not be
emmetropic (0 diopters). For example, near sight may be improved by a manifest
which is slightly
myopic. Following an analysis similar to that discussed above for pupil size
dependency, an
optimum target refraction can be calculated based on acuity as a function of
power in a set of eyes
treated with the prescribed refractive shape. Figs. 34 and 35 show the
distance and near acuity as
a function of manifest, respectively. Distance and near acuity versus manifest
can be expressed by
the following non-linear equations.
Near _Acuity = Ao + A(Manifest)+ B(Manifest) 2 C(Manifest)3 + ...
Dis tan ce _Acuity = Ao + A(Manifest)+ B(Manifest) 2 C (Man ifest )3 +...
[0262] Applying a first order approximation to the above equations, and using
measurements
from previous data, the near and distance acuity as a function of manifest can
be expressed as
follows.
Near _Acuity = 0.34 + 0.67(Manifest)
Dist _Acuity = ¨0.04 ¨ 0.13(Manifest)
[0263] The intersection between the two functions can be solved as follows.
0.34 + 0.67 (Manifest ) = ¨0.04 ¨ 0.13 (Manifest )
(-0.04 ¨0.34)
Manifest == ¨0.48 [Diopters ]
0.67 +0.13
[0264] The point where the two lines meet is about -0.5D. Therefore, it can be
useful to set the
target manifest to -0.5D. The target manifest equations can be refined based
on additional data
53
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
collected from those patients that are treated with the refractive shape. As
noted above in
reference to Fig. 28, a prescriptive shape may be the sum of a base curve
treatment and a central
refractive add. It is possible to change the base shape to compensate for any
power offset
contributed by the central refractive add to the distance manifest.
[0265] PAR refinements applied to particular patients
[0266] As additional data is accumulated, it is possible to calculate the
higher order terms of
Equation B. More particularly, it is possible to calculate the higher order
terms from additional
subjects who have been treated with refractive shapes corresponding to
constant and linear term
adjustments. For example, a group of patients can be treated according to the
PAR of 2.5/5.3
discussed above, and based on their results, the PAR can be further refined.
[0267] A group of patients had adjustments made to their prescriptive
presbyopic shape based on
results from the analysis discussed above. The patients were treated with
shapes based on a
constant PAR of 2.5/5.6 as applied to the central add shape, with a target
manifest of -0.5D. These
adjustments rotate the equation about the 5.6 mm line toward horizontal
because the near effect is
a constant. For example, a 5 mm pupil patient has the same near correction as
a 6 mm pupil
patient, which means that their near acuity should be the same, i.e. a plot of
the near acuity versus
pupil size will be a substantially flat line. Figs. 36 and 37 show the result
of these adjustment on
this group of patients. As predicted, the lines rotated. The distance acuity
of 7 of 8 of these
patients was 20/20 (logMAR 0) or better, and the 8th was 20/20+2. Their near
acuity slopes have
also flattened, with 7/8 patient having simultaneous 20/32 -2 acuity or
better, and the 8th 20/40.
Table 4 summarizes the acuity and power measures.
Table 4
Near acuity 0.19 0.1
Distance acuity -0.08 0.08
MRS -0.19 0.26
[0268] This PAR adjusted group has, which is a good result for a presbyopia
treatment.
[0269] Optimizing A Refractive Shape For A Vision Condition
[0270] It is possible to define customized refractive shapes such that they
are optimized to treat a
particular patient. In one approach to defining an optimized refractive shape,
the power of the
refractive shape may be based on the central power add of a prescriptive
shape, and the power
change requirement of the particular patient. Other approaches may involve
deriving an
54
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
appropriate prescription so as to provide a desired overall effective power of
the eye at different
viewing conditions, again by taking advantage of the changes in pupil size.
[0271] Determining a desired central power add of a prescriptive refractive
shape
configured to treat the vision condition
[0272] A prescriptive shape can be selected for treating the vision condition
of the particular
patient. For example, the prescriptive shape shown in Fig. 28 can be selected
for treating a
particular patient having presbyopia. As previously discussed, the central
power add of this
exemplary prescriptive shape can be about -3.1 diopters.
[0273] Determining a power change of a particular patient
[0274] The desired power change of a particular patient can vary widely, and
often depends on
the patient's desired treatment or a recommendation from a vision specialist.
For example, the
desired power change of a particular patient having presbyopia can be about -
2.5 diopters. The
desired power change may be linear or non-linear.
[0275] Determining a pupil diameter parameter of the particular patient
[0276] When defining a refractive shape for treating a vision condition in a
particular patient, it
is helpful to determine the pupil diameter parameter of the particular
patient. Pupil diameters can
be measured by, for example, a pupillometer. Pupil diameter parameters can
involve, for example,
the patient's pupil diameter as measured under certain distance and lighting
conditions, such as
under photopic conditions while the patient gazes at infinity (distance-
photopic). Pupil diameter
parameters can also involve pupil diameter measurements under other conditions
such as distance-
mesopic, distance-scotopic, near-photopic, near-mesopic, or near-scotopic.
Still further additional
measurements at other viewing conditions, such as at intermediate distances
and/or moderate
lighting conditions, may also be measured. Often, pupil diameter parameters
will be based on two
pupil diameter measurements. For example, a pupil diameter parameter can be
the value of the
particular patient's pupil diameter at distance-photopic minus the patient's
pupil diameter at
distance scotopic. According to this example, if the distance-photopic pupil
diameter is 0.7 mm
and the distance-scotopic pupil diameter is 0.2 mm, then the pupil diameter
parameter is 0.7 mm
minus 0.2 mm, or 0.5 mm.
[0277] Defining a refractive shape configured to treat the particular patient,
the power of
the refractive shape at a given diameter based on: the central power add of
the prescriptive
refractive shape, the power change requirement of the particular patient, and
the pupil
diameter parameter of the particular patient
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0278] When defining the refractive treatment shape, it can be beneficial to
base the power of
the refractive shape (Power/Shape Requirement) at a given diameter based on
the central power
add of the prescriptive refractive shape, and on the power change requirement
of the particular
patient. For example, the power of the refractive shape can be a function of a
given diameter, as
expressed in the following formula.
Power/Shape_Requirement = Co + A(pupil_diameter)
where Power/Shape Requirement is the power of the refractive shape at a
particular
Pupil_Diameter, Co is the central power add of the prescriptive refractive
shape, and A is
calculated as
A = (PRC-Co)/PDP
where PRC is the power change requirement for the particular patient, and PDP
is the pupil
diameter parameter (obtained, for example, by subtracting the diameter of the
pupil measured
when the patient is gazing at infinity from the diameter of the pupil measured
when the patient is
looking at a near object under identical light conditions). Given the values
discussed above, the
Power/Shape_Requirement (PSR) can be calculated as follows.
PSR = -3.1 diopters + R-2.5 diopters - -3.1 diopters)/0.5 mm)](pupil_diameter)
Or
PSR = -3.1 diopters + 1.2(pupil_diameter)
[0279] Other Pupil Diameter Parameters
[0280] It is also possible to calculate a pupil diameter parameter based on a
pupil diameter
change slope as measured under certain distance and lighting conditions, for
example, as the
patient gazes at infinity while the lighting conditions change from photopic
to scotopic
(distance-photopic to scotopic). Pupil diameter parameters can also involve
pupil diameter change
slopes such as near-photopic to scotopic, photopic-distance to near, mesopic-
distance to near, or
scotopic-distance to near.
[0281] The Effective Power
[0282] The effective power (e.g., linear power model or higher order model)
can be used to
calculate or derive a presbyopic shape, optionally based on the following
parameters.
F.1. Emmetropic at distance (photopic and mesopic lighting conditions)
a. This can determine a maximum diameter of the add
F.2. Near can have an effective power of -2.5D (or more, if desired by the
patient
56
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
F.3. The rate of change of power for the add-treatment combination can have
one
of the four:
i. The same power rate of change as the photopic ¨
Distance to near
ii. The same power rate of change as the mesopic ¨ Distance to near
iii. The same power rate of change as the scotopic ¨ Distance to near
iv. Non-linear rate of change similar to the above, but is optimized to give
better simultaneous distance and near vision.
[0283] For an eye gazing into infinity, under photopic conditions, the
theoretical pupil size at
emmetropia can vary within the population. Moreover, the pupil diameter can
further vary when
the eye is used for different tasks. For example, the pupil diameter can
decrease as the eye's gaze
changes from infinity to a near object. As the eye changes from a distance
gaze to a near gaze, the
typical pupil diameter decreases. This change in pupil diameter may be linear
with convergence
and sigmoid with accommodation. In an eye treated with an exemplary
prescriptive shape, the
pupil diameter at near gaze can typically have the inner region of the
prescriptive shape as the
dominant refractive component. Consequently, the change of pupil size from
larger to smaller
(distance gaze to near gaze) can be equivalent to a change in power. In
comparison, the distance
gaze pupil will have an effective power based on the combination of the inner
region add and the
outer region of the prescriptive shape, with the outer region becoming a more
dominant refractive
component. Therefore, each refractive shape can be customized to each
particular individual
because of the many different combinations available. By changing the power of
the cornea, for
example, from emmetropia at the "distance" pupil size to within a range of
about -1.0 diopters to
about -4.0 diopters myopic for "near" pupil size, it may be possible to
mitigate presbyopia.
[0284] A general prescription may go as follows. First, measure the continuous
pupil size and/or
size change at different distances and lighting conditions, such as for at
least one (optionally two
or more, in some cases all) of: Distance ¨ Photopic; Distance ¨ Mesopic,
Distance ¨ Scotopic,
Near ¨ Photopic, Near ¨ Mesopic, and/or Near ¨ Scotopic. The pupil size can be
affected by the
lighting conditions as well as viewing distances. The refractive shape can
also include adjustments
and/or optimization for lighting. In photopic conditions, the pupil is
typically constricted. In
scotopic conditions, the pupil is usually dilated. Under mesopic conditions,
the pupil can be
variably dilated or constricted depending on the specific type of mesopic
condition. Second,
calculate the pupil diameter continuous rate of change for the following
combinations: Distance ¨
photopic to scotopic, Near ¨ photopic to scotopic, Photopic ¨ Distance to
near, Mesopic ¨ Distance
to near, and/or Scotopic ¨ Distance to near. It is possible to design a shape
and ablation size such
57
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
that patient is substantially emmetropic as pupil size goes from larger
(distant) to smaller (near),
typically within a range.
[0285] The presbyopic lens power can compensate focus such that the lens is
the inverse of the
rate of pupil change. To do this, the power can change (for example -3D) for
different pupil
diameters.
Power I Shape _ Re quirement
= Co + A(pupil _diameter)+ B(pupil _diameter) 2 C(pupil _diameter)3 +...
[0286] The Power / Shape_Requirement in the above equation may be effective
power, and/or
may be manifest power. The power can change with changes in pupil diameter.
For a linear
power shape, the coefficient A can be calculated as follows.
d(power)
________________________________ =A
d(pupil _diameter)
[0287] Solving for the linear coefficient,
A = PowerChange Requirement ¨ Co
pupil _diameter _rate _of _change
[0288] The target manifest can be targeted to the patient's request or a
doctor's recommendation
by using the effective distance power equation as described above in the
"target manifest" section.
[0289] Multifocal shapes
[0290] A good refractive shape (including a multi-focal shape) may be at or
near an optimum
compromise between distance and near sight. The near add has an "effective"
power - it may not
have a single power because of the multi-focal shape. The sum of the
peripheral and central add
may give the distance power ¨ again it may not have a single power because of
the multi-focal
shape.
[0291] The Age Dependent Presbyopic Shape
[0292] As discussed above, as one ages, accommodation decreases. This is shown
in Fig. 38.
At 60, accommodation can decrease significantly, even to nearly zero. Studies
have shown that
pupil sizes decrease as one gets older. As seen in the figure, the slope or
rate of change in
accommodation also changes with age. It is possible to optimize the pupil
dependencies to the age
58
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
related change in accommodation. The rate of distance and near acuities for a
central add shape
can be
Near_acuity = -2.103 + 0.37879 * Pupil size (Dim)
Distance acuity = 0.40001 - 0.0677 * Pupil size (Dim)
[0293] According to these equations, as the pupil size decreases, the near
acuity gets better, at a
rate of 0.37 lines per millimeter. The distance acuity gets worse, but at much
slower rate of 0.07
lines per millimeter. Therefore, it is possible to optimize the treatment
parameters for the patient's
age by targeting the treatment for less myopia. It is possible to allow a
shift in the centering of the
"range" by taking the residual accommodation into account in the customization
of the treatment.
[0294] It is possible that the optimum shape may be on a "linear" power
approximation as
discussed above, but it may consist of higher orders. Though the effective
power can be given by
the equation above, the shape can be constant over, for example, a central
2.5mm and have a
curvature gradient that will blend the central add to the peripheral region.
With this shape it may
be beneficial to choose the diameter of the central add to match the patients
near pupil such that
the near pupil will encompass only the central add when it's at its smallest,
and the gradient will be
customized to the patient's pupil size rate of change.
[0295] Hence, by modeling the residual accommodation, the range of pupil
change may be
shifted to optimize the "life" long presbyopic correction.
[0296] Systems
[0297] The present invention also provides systems for scaling refractive
shapes and providing
practical customized or optimized refractive shapes that mitigate or treat
presbyopia and other
vision conditions in particular patients. The systems can be configured in
accordance with any of
the above described methods and principles.
[0298] For example, as shown in Fig. 39, a system 1000 can be used for
reprofiling a surface of
a cornea of an eye 1600 of a particular patient from a first shape to a second
shape having
correctively improved optical properties. System 1000 can comprise an input
1100 that accepts a
prescriptive shape specific for treating the vision condition, an input 1200
that accepts a pupil
dimension of the particular patient, a module 1300 that scales a dimension of
a central portion of a
refractive shape based on the pupil dimension of the particular patient and an
attribute of at least
one eye previously treated with the prescriptive shape, a processor 1400 that
generates an ablation
profile, and a laser system 1500 that directs laser energy onto the cornea
according to the ablation
59
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
profile so as to reprofile a surface of the cornea from the first shape to the
second shape, wherein
the second shape corresponds to the refractive shape.
[0299] Calculating of Presbyopia Mitigating Prescriptions
[0300] Methods, Systems, and Devices described herein can be used to generate
prescriptions
for treatment of refractive errors, particularly for treatment of presbyopia.
Such treatments may
involve mitigation of presbyopia alone, or may treat a combination of
presbyopia with other
refractive disorders.
[0301] As described above, presbyopia is a condition where the degree of
accommodation
decreases with the increase of age. Most people have some degree of presbyopia
by the age of
about 45.
[0302] Treatments of presbyopia may involve passive and/or active procedures.
In passive
procedures, treatment or mitigation is performed in such a way that an
improved balance between
near vision and distance vision is provided and maintained. In an active
procedure, restoration of
full or partial accommodation is a goal. So far, active procedures for the
correction of presbyopia
have not been fully successful.
[0303] With passive procedures, it is desirable to provide an improved and/or
optimal balance
between near vision and distance vision. In order to do that, patients may
sacrifice some of their
distance vision to gain improved near vision. In addition, they may sacrifice
some contrast
sensitivity because of the introduction of the asphericity of the new optics
of the eye. Fortunately,
the sacrifice of distance vision and contrast sensitivity may be mitigated by
taking advantage of a
pupil shrinkage when the eye accommodates.
[0304] As described below, an analytical solution for a presbyopia shape can
be achieved based
on a desire for different powers at different pupil sizes. In order to
understand this, we can take
advantage of a concept of optical power that depends on the change of pupil
size and might also
depend on wavefront aberrations other than defocus terms. We will concentrate
on the pupil size
dependency in this description.
[0305] The following approach considers the correction as a "full pupil"
correction rather than
"partial pupil" correction as employed with a central add. Healing effect,
flap effect as well as how
the effective power correlates with the manifest refraction may be addressed
with empirical
studies, allowing these effects to be fed back into the following calculations
and/or a laser ablation
planning program as appropriate so as to provide optimized real-world results.
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0306] Effective Power and Its Application to Presbyopia
[0307] used herein, "effective power" means the optical power that best
matches the manifest
sphere at a certain pupil size. With wavefront based ocular aberrations, the
defocus-dependent
effective power can be written as
4-&
peff = 2
R2 (1)
where R stands for the pupil radius in mm when c2 is the Zernike coefficient
given in microns in
order to get the effective power in diopters, and Peff is effective power.
When a wavefront map is
defined in radius R with a set of Zernike polynomials, when the pupil shrinks
the smaller map, if
re-defined with a new set of Zernike polynomials, will have a different set of
Zernike coefficients
than the original set. Fortunately, analytical as well as algorithmatical
solutions of the new set of
Zernike coefficients exist. If the original set of Zernike coefficients is
represented by { ci} that
corresponds to pupil radius rj, then the new set of Zernike coefficients
{b}that corresponds to
pupil radius r2 can be expressed by a recursive formula as
b2 112(i + j) +1 (2i + j)! n Ilk
+1 (-1)k12-1 (k 1 2 + i)!
z k
zo = e2 LH)c20 0+õ
b
,=0 2i +1 ./1 (20! k-2(z+1) 2i +1 (k
1 2 ¨ i)!(2i)!
step2
[0308] where e = r2/rj, n is the maximum radial order. As an example, if we
set i = 1, and n = 4,
we have the following formula
b20 = 11e20
15(1¨e2)63]e2
[0309] Therefore, a power profile with pupil size can be given as a condition
to obtain an optical
surface for presbyopia correction.
[0310] In order to obtain a presbyopia prescription (which will here be an
optical shape), let's
assume that we know the power profile or desired effective optical powers for
different viewing
conditions so as to mitigate presbyopia. From the power profile, we can in
general do an
integration to calculate the wavefront shape. In the following, we consider
three cases where two,
three, or four power points (different desired effective optical powers for
different associated
viewing conditions, often being different viewing distances and/or pupil
diameters) are known.
[0311] Two-Power-Point Solution
61
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0312] Let's consider radially symmetric terms Z2 and Z4 , when the pupil
radius is changed
from R to eR, where e is a scaling factor not larger than 1, since the new set
of Zernike coefficients
for the defocus term can be related to its original coefficients as
b20 = [e20 _
v15(1¨e2)c40]e2.
(2)
[0313] Substituting c2 with b2 , and R2 with e2R2 in Equation 1 using
Equation 2, we have
4-&2 e2)e4o _R2p
(3)
[0314] Suppose we request power po at radius e0R, and p1 at radius e IR, an
analytical solution
of the original wavefront shape, which is represented by c2 and c4 , can be
obtained as
2 2
c 0 = (1 ¨ ei ) po ¨ (1¨ eo)pi R2
2
41,(e02 ¨e12)
(4)
o ¨ P
c4 = P 1 R2
121S(e02 el2
[0315] As an example, let's consider a pupil with a dim distance size of 6mm,
requesting
effective power of OD at pupil size 6mm and bright reading pupil size of
4.5mm, requesting
effective power of ¨1.5D. Substituting eo = 6/ 6 = 1, e1 = 4.5/6 = 0.75, and
po = 0 and
p1 = , we get c2 = 0 and c4 = ¨1.15. Figs. 40 and 41 show the
presbyopia shape and
effective power as a function of pupil size. It is very close to a linear
relationship.
[0316] Three-Power-Point Solution
[0317] Let's consider radially symmetric terms Z2 , Z4 and Z6 , when the
pupil radius is
changed from R to eR, where e is a scaling factor not larger than 1, since the
new set of Zernike
coefficients for the defocus term can be related to its original coefficients
as
b2o _ re2o
15(1 ¨e2)c4 +11271(2-5e2 3e4)e6o ie 2 ,
(5)
[0318] Substituting c2 with b2 , and R2 with e2 R2 in Equation 1 using
Equation 5, we have
4.&2 ¨121(1¨ e2)c4 +121,F7(2 ¨ 5e2 3e4)c6o _ _R2 p
(6)
62
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0319] Suppose we request power p0 at radius eoR, p1 at radius e IR, and p2
and radius e2R, an
analytical solution of the original wavefront shape, which is represented by
c2 ezt and 4 , can be
obtained as
co
(1¨ ei2 )(1¨ e22 )(4 ¨ e22 )p0 ¨ (1-4 )(1¨ e22 )(4 ¨ e22 )pi + (1¨ e02 )(1¨
ei2 )(e02 ¨ ei2 )192 R2
0
= _________________________________________________________________
4.µ5(ei2 e22 )(e02 ei2 )(e02 e22 )
co 0 (5 _ 3c12 _ 3c22)(4 _ c22)po _ (5 _3e02 _3e22)(e02 _ c22)pi + (5
_3e02 _34)(4 _
./-
)2 R2
=
e22 )(e02 ei2 )(e02 e22 )
0 (ei2 ¨e)
)po (e02 e22 )pi (e02 e 2 )\
.1'
1 2 R2
C6 =
36. j(ei2 e22 )(e02 ei2 )(e02 e22 )
(7)
[0320] As an example, let's consider a pupil with WaveScan pupil size of 6mm,
and dim
distance pupil size of 6mm, requesting effective power of OD and bright
reading pupil of 3.5mm,
requesting effective power of ¨1.5D. In between are the dim reading and bright
distance, with
combined pupil size of 4.5mm with effective power of ¨0.5D. Substituting e0 =
6/ 6 =1,
= 4.5/6 = 0.75 , and e2 = 3.5/6 = 0.583 as well as p0 = 0 , p1 =¨O.6 and p2 =
¨1.5, we get
c2 = , = 0 0
¨0.31814 and c6 = 0.38365. Figs. 42 and 43 shows the presbyopia shape and the
effective power as a function of pupil sizes.
[0321] Four-Power-Point Solution
[0322] Let's consider radially symmetric terms Z2 , Z4 , Z6 and Z8 , when
the pupil radius is
changed from R to eR, where e is a scaling factor not larger than 1, since the
new set of Zernike
coefficients for the defocus term can be related to its original coefficients
as
b2o _ [c2o _
15(1¨e2)c4 +V271(2_5e2 +3e4)e60
3 (10 ¨ 45e 2 +63e4 ¨ 28e6)c8o ie 2
(8)
[0323] Substituting c2 with b2 , and R2 with e 2R 2 in Equation 1 using
Equation 8, we have
41hc2 ¨12AS(1¨ e2)c4 +12VT7(2 _5e2 +3e4)e60 _12(10 ¨ 45e 2 +63e4 ¨ 28e6)c8o
_ _R2p (9)
[0324] Suppose we request power p0 at radius eoR, p1 at radius e 1R, p2 and
radius e2R, and p3
and radius e3R, an analytical solution of the original wavefront shape, which
is represented by c2
ezt c6 and c8 , can be obtained as:
63
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
0 2 a3P0 ¨API +2/3P2 ¨ (53P3
C2 = ¨R
4-N/D,
C4
0 R = 2 a20 ¨ fi2PI r= 2P2 ¨82133
252J2 , (10)
0 2 alP0 ¨ API r= ip2 ¨ (51p3
e6 = R
144, , F 72
0 2 croPo ¨ fi01:31+ r= 0P2¨ 60133
c8 = ¨R
3362
where
A = (e02 _e12)(e02 _e22)(e02 _e32)(e12 _e22)(e12 _e32)(e22 _e32)
(11)
ao = (e12 _e22)(e12 _e32)(e22 _e32)
(12)
160 = (e02 _e22)(e02 _e32)(e22 _e32)
(13)
70 = (e02 _e12)(e02 _e32)(e12 _ e32 )
(14)
(50 = (e02 _e12)(e02 _e22)(e12 _e22)
(15)
ai = [9 ¨ 4(e e22 e32 wro
(16)
161 = p _ 4(e02 e22 e32 )]/30
(17)
71 = [9 _ 4(e02 el2 e32 )] 70
(18)
61 = [9 _ 4(e02 el2 e22 )](50
(19)
a2 = [45 ¨35(e +e; + 4) 21(eize22 ei2e32 e22e32)]a0
(20)
/32 = [45 ¨ 35(e02 +e2 + e32 ) 21(e02e22 e02e32 e22e32 )]/30
(21)
72 = [45 ¨35(e02 +e2 + e32 ) 21(e02e12 e02e32 ei2e32 )] 70
(22)
62 = [45 ¨35(e02 +e2 + e22 ) 21(e02e12 e02e22 ei2e22 )]5.0
(23)
a3 = (1¨ e)(1¨ 4)(1¨ 4 )ao
(24)
/33 = (1¨ e02)(1¨ e22)(1¨ e32)/30
(25)
73 = (1¨ e02)(1¨ ei2)(1¨ e32 )70 (26)
63 = (1¨ e02)(1¨ ei2)(1¨ e22 )80
(27)
[0325] As an example, let's consider a pupil with WaveScan pupil size of 6mm,
and dim
distance pupil size of 6mm, requesting effective power of OD and bright
reading pupil size of
3.5mm, requesting effective power of ¨1.5D. We also request that the bright
distance pupil size to
be 5mm and dim reading pupil size of 4.5mm, with effective power of ¨0.2D and
¨0.5D,
respectively. Substituting e0 = 6/ 6 =1, el = 5/6 = 0.833, e2 = 4.5/ 6 = 0.75
and
e3 = 3.5/ 6 = 0.583 as well as po = 0 , p1 = ¨0.2 , p2 = ¨0.5 and p3 = ¨1.5 ,
we get c2 = 0 ,
= ¨0.2919 , c 6 = 0.3523 and c 8 = ¨0.105 . Fi
c4
gs. 44 and 45 show the presbyopia shape and the
effective power as a function of pupil sizes. Note that both the presbyopia
shape and the effective
64
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
power are similar to those shown in Figs. 42 and 43. However, the shape and
power given with 4-
term solution is smoother and have a flatter power at larger pupil sizes.
[0326] It is also possible to use the same approach to obtain analytical
solutions for conditions
that use more than four power points. For example, when we use five power
points, we could use
up to 10th order of Zemike coefficients to describe the aspheric shape that
satisfies the power
profile defined with five power points. Similarly, six power points can define
an aspheric shape
using 12th order of Zernike coefficients. Because more power points can in
general make the
analytical solution more difficult, another way of approaching the solution is
by more complex
numerical algorithms. Due to the availability of the recursive formula, the
equations that lead to
analytical solutions might be converted to an eigen system problem, which does
have numerical
solutions, optionally making use of the methods of William H Press, Saul A.
Teukolsky, William
Vetterling, and Brian P. Flannery, in Numerical Recipes in C++, (Cambridge
University Press,
2002). Such a solution may be more accurate than use of discrete power point.
[0327] Discussion
[0328] It is helpful to address how many terms to use in determining the
presbyopia shape. In
the two-power-term solution, we use the pupil sizes as well as the
corresponding desired powers.
We can use this solution for a somewhat "bifocal" design with one distance
pupil size and power
(which should be zero to keep the eye at emmetropia) and one reading pupil
size and its
corresponding power. From Figs. 40 and 41, the effective power follows a
rather linear
relationship with pupil size changes. This may not be ideal in that the
distance power may tend to
become myopic. With a 3-power-term solution, we have one more freedom to
choose the power in
a middle pupil size and in fact the solution is rather close to a 4-power-term
solution when
carefully designed. Unfortunately, with a 3-power-term solution, the bright
distance pupil and the
dim reading pupil tend to be averaged and so do the corresponding powers. This
may become too
inflexible to design an ideal shape. Therefore, the 4-power-term solution,
which tends to give a
more favorable reverse Z-curve, should be used in the practical
implementation. The reverse Z-
curve such as that shown in Fig. 46A, a positive power gradient region between
two lower slope
(or flat) regions within a pupil size variation range for a particular eye,
may be a beneficial
effective power characteristic for presbyopia mitigation.
[0329] Even with a 4-power-term solution, choosing effective powers in-between
dim distance
pupil and bright reading pupil should be carefully considered. For instance,
in order to satisfy
restaurant menu reading, we might want to increase the power for dim reading.
In this case, an
unfavorable S-curve would exist, as is also shown in Fig. 46A. Presbyopia-
mitigation shapes
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
corresponding to the S-curve and Z-curve shapes are shown in Fig. 46B. These
results were
generated for a 6mm pupil with the dim distance pupil at 6mm with a power of
OD, the bright
distance pupil at 5mm with power of ¨0.2D and ¨0.7D, the dim reading pupil at
4.5mm with a
power of ¨1.2D and the bright reading pupil at 3.5mm with a power of ¨1.5D. To
reduce the
fluctuation of effective power, we can also increase the power in bright
distance and in this case
the distance vision can be affected (in addition to the contrast drop due to
asphericity).
[0330] Another parameter we can set is desired reading power. Optionally we
can give the
patient full power; say 2.5D, so the treatment can be sufficient to treat
presbyopia for the patient's
life span. However, the natural pupil size decreases with increasing age.
Therefore, a shape well
suited to a patient at the age of 45 could become deleterious at the age of
60. Secondly, not
everyone easily tolerates asphericity. Furthermore, too much asphericity can
reduce the contrast
sensitivity to a level that distance vision would deteriorate. As such,
measurement of a patient's
residual accommodation becomes beneficial in the success of presbyopia
correction. In addition,
the various pupil sizes at different lighting conditions and accommodation can
be measured
systematically and more accurately. Such measurements may employ, for example,
a
commercially available pupilometer sold by PROCYON INSTRUMENTS LIMITED of
London, United
Kingdom, under the model number Procyon P-2000 SA. A wide variety of
alternative pupil
measurement techniques might be used, including visual measurements,
optionally using a
microscope displaying a scale and/or reticule of known size superimposed on
the eye, similar to
those employed on laser eye surgery systems commercially available from AMO
Manufacturing
USA, LLC in Milpitas, California.
[0331] The influence of high order aberrations on the effective power, as
described above
regarding the power map, may also be incorporated into the presbyopia-
mitigating shape
calculations. This may involve integration over the entire power map, i.e.,
the average power, with
appropriate adjustment so as to avoid overestimating power (that may otherwise
not agree with the
minimum root-mean-square (RMS) criterion) and so as to correlate with patient
data. The
influence of high order spherical aberrations on effective power calculation
should not be entirely
ignored. In particular, the influence on the depth of focus, and hence to the
blur range during
manifest refraction test, can be determined using clinical testing.
[0332] Taking advantage of the ability to calculate presbyopia shapes based on
effective power,
presbyopia-mitigating shapes can be derived and/or optimized based on the
following
considerations. First, image quality of the presbyopia shape at different
viewing conditions can be
evaluated. To do so, optimization of the shape itself can be pursued. This can
be done in several
66
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
ways, such as using diffraction optics (wave optics) or geometrical optics
(ray tracing). Because
we are dealing with aberrations of many waves, it may be impractical to use
point spread function
based optical metrics. However, since the aberration we introduce belongs to
high orders only,
wave optics may still work well. In fact, a comparison of Zemax modeling with
three wavelengths
and using verification tools (wave optics), as shown in Fig. 16, with 7-
wavelengths show almost
identical results in both point spread function (PSF) and modulation transfer
function (MTF). Fig.
47 shows some derived shapes for a 5mm and a 6mm pupil, while the
corresponding MTF curves
are shown in Fig. 48. The simulated blurring of eye chart letter E for both
cases is shown in Fig.
49. These letters graphically illustrate verification of presbyopia shape
using a goal function with
7-wavelengths polychromatic PSF and a 20/20 target. The first image shows a
target at 10m. The
second to the last image shows targets from lm to 40cm, separated by 0.1D in
vergence. One
diopter of residual accommodation is assumed for each. Even without
optimization, the optical
surface shown gives almost 20/20 visual acuity over 1.5D vergence.
[0333] The above approach is valid to apply in contact lens, intra-ocular
lens, as well as
spectacles, as well as refractive surgery. Such calculations for refractive
surgery may be adjusted
for the healing effect as well as the LASIK flap effect based on empirical
studies and clinical
experience.
[0334] As established above, it is possible to obtain analytical expressions
for the Zernike
coefficients of the first few spherical aberrations of different orders to
create an aspheric shape for
presbyopia correction based on one or more desired effective powers. Healing
effect, flap effect,
and the correlation of effective power with manifest refraction will benefit
from additional patient
data and empirical studies to further refine the presbyopia shape so as to
(for example) more
accurately plan the shape for future ablation.
[0335] Figs. 50A and 50B illustrate exemplary desired power curves and
treatment shapes for
mitigating presbyopia of a particular patient. The four power point solution
was used to establish
these shapes. For a 6mm pupil, the following Table 5 describes the four
conditions or set points
from which the shape was generated:
67
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
Table 5
Conditions 6mm Pupil 5mm Pupil
Effective power Pupil size (mm) Effective power Pupil size (mm)
1 OD 6 OD 5
2 -0.5D 5 -0.5D 4.2
3 -1D 4.5 -1D 3.8
4 -1.5D 3.4 -1.55D 3.1
Table 5
[0336] Fig. 50A shows the effective power profiles, while Fig. 50B shows the
corresponding
presbyopia shapes. To model the healing and LASIK flap effect, we uniformly
boost the shape by
15%. In addition to the added presbyopia shape, we also used -0.6D physician
adjustment in the
wavefront prescription generation to offset myopic bias to aim emmetropia at
normal viewing
condition (bright distance) after surgery.
CMTF Based On PSF
[0337] As discussed elsewhere herein, the compound modulation transfer
function (CMTF)
provides a useful optical metric for evaluating any optical design, and in
general provides an
effective tool for simulation, evaluation, optimization, and design of optical
surface shapes for
laser refractive surgery and other vision treatment modalities. In exemplary
cases, CMTF can be
used to evaluate shapes for treating presbyopia of the eye, in the context of
laser refractive
surgeries, contact lens prescriptions, intraocular lenses, and the like.
[0338] A CMTF value can be calculated in a variety of ways. For example, a
CMTF value can
be calculated based on a monochromatic point spread function (PSF). It is also
possible to
calculate a CMTF value based on a polychromatic point spread function (PSF).
[0339] Techniques for obtaining a polychromatic PSF are discussed elsewhere
herein, as well as
in US 2010/0103376, which is incorporated herein by reference. In some cases,
Fourier transform
of the phase screen may be used for determining a point spread function,
according to diffractive
theory. In other cases, ray tracing may be used to determine a point spread
function. As noted
elsewhere here, a point spread function can be used for diagnostic purposes,
treatment purposes,
analyzing optical acuity, and optimizing optical treatment shapes, such as
shapes for treating
presbyopia in a patient.
[0340] Given a particular polychromatic PSF, it is possible to perform a
Fourier transform of the
PSF to obtain a modulation transfer function, which may involve determining
the modulus.
Multiple modulation transfer functions obtained based on different spatial
frequencies can be used
68
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
to determine a CMTF. Exemplary techniques for performing a Fourier transform
of a PSF to
obtain an MTF are described in J. W. Goodman, Introduction to Fourier Optics,
3rd ed (Roberts &
Company, 2005), the content of which is incorporated herein by reference.
Similarly, in some
cases an MTF can be determined from a PSF in a manner which does not involve a
Fourier
transform of the PSF. For example, it is possible to calculate the integration
of the overlap area of
a pupil function (e.g. overlap area of two pupil apertures), to obtain an
optical transfer function
(OTF). The MTF can be based on a modulus, or magnitude, of the OTF. Exemplary
integration
techniques are describe in J. W. Goodman, Introduction to Fourier Optics, 3rd
ed (Roberts &
Company, 2005), previously incorporated. Where there are aberrations, it may
be desirable to
obtain the MTF based on the PSF Fourier transform approach, instead of the
integration approach.
According to these techniques, it is possible to obtain an MTF or CMTF based
on a PSF or PPSF.
[0341] Because modulation transfer functions can be calculated based on point
spread functions,
it is desirable to obtain or provide point spread functions which are accurate
and appropriate for
the intended use. As described elsewhere herein, according to some embodiments
polychromatic
point spread functions are particularly well suited for use for applications
involving the optics of
the human eye.
CMTF Threshold
[0342] Embodiments of the present invention encompass system and methods for
evaluating an
image quality provided by a vision treatment shape. For example, techniques
may include
obtaining a plurality of through-focus compound modulation transfer function
(CMTF) values for
the vision treatment shape, comparing these CMTF values to a CMTF threshold
value, and
evaluating the image quality based on the comparison.
[0343] According to some aspects of the present invention, it is useful to
determine a CMTF
threshold value for use in evaluating the image quality. A CMTF threshold may
represent a
minimal CMTF value, below which the image quality may not be considered to be
acceptable or
desired. The CMTF threshold can be used to evaluate whether a particular
optical surface or shape
may be effective for treating a particular vision condition. In some
instances, a CMTF threshold
can have a value of about 0.1. In some instances, a CMTF threshold can have a
value of about 0.3.
[0344] FIG. 51 illustrates through-focus results for a 20/20 eye chart letter
E convolved with
certain point spread function models (e.g. monochromatic, polychromatic, and
no aberration
polychromatic) across a vergence range (e.g. -1.0 D to 3.0 D) for a 5.0 mm
pupil size. Such
through-focus results can be obtained by moving a vision target throughout a
range of vergence,
69
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
for example, from a distant location (e.g. 0 D, which corresponds to infinity)
to a near location
(e.g. 3.0 D).
[0345] For FIG. 51, through-focus (in terms of vergence) wavefront maps are
used to generate
the point spread function, using both the monochromatic and polychromatic PSF
models. A no
aberration situation, which uses a polychromatic PSF model, can be compared to
the
monochromatic and polychromatic PSF results. As seen here, the polychromatic
PSF provides
improved image results over the monochromatic PSF at 0.5D (distant), and
between 1.5D and 3.0
D (near).
[0346] As shown here, visual inspection of the results at 1.0 D vergence
indicates that the
convolved eye chart letter image is difficult to discern. Relatedly, visual
inspection of the results
at 0.5 D vergence indicates that the eye chart letter image associated with
the PPSF model is
discernible (e.g. visibly apparent borders of letter E indicate acceptable
acuity or resolution, albeit
with low contrast to surrounding background), whereas the eye chart letter
image associated with
the MPSF model is not so discernible. Surgeons, diagnostic device operators,
and other personnel
can visually inspect such results to determine discernibility, or to compare
discernibility between
different images, and to make selections or determination based on the visual
inspection.
[0347] Whereas FIG. 51 provides convolution images for the three different
treatment shapes,
FIG. 52 provides corresponding CMTF value curves for the three same shapes.
Specifically, FIG.
52 shows the results of CMTF through-focus CMTF curves for one presbyopic
correction shape
using monochromatic and polychromatic PSF models, as compared with a
diffraction-limited (no
aberration) case. The CMTF values here were calculated using spatial
frequencies of 10, 15, 20,
and 30 cpd (cycles per degree). For each of (i) the diffraction limited case,
(ii) the presbyopic
correction shape using monochromatic PSF, and (iii) the presbyopic correction
shape using
polychromatic PSF, the peak CMTF is at or near the 0 Diopter vergence. The
presbyopia shapes
were optimized with the noted set of cpd spatial frequencies.
[0348] For the purpose of presbyopia corrective treatments, for example, the
through-focus
CMTF curves of FIG. 52 can be directly compared with the convolved eye chart
letters shown in
FIG. 51, in order to compare the various correction shapes at selected
vergences. Based on the
comparison, it is evident that CMTF values of 0.1 or more correspond with
visually discernible
letters. For example, at 0.5D as shown in FIG. 51, the monochromatic PSF
convolved eye chart
letter is not discernible, whereas the polychromatic PSF convolved eye chart
letter is discernible.
Relatedly, at 0.5D as shown in FIG. 52, the monochromatic PSF CMTF is below
0.1, whereas the
polychromatic PSF CMTF is about 0.1. With reference to FIGS. 51 and 52,
exemplary
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
embodiments may include calculating a through-focus curve, or through-vergence
curve, with a
particular optical metric, such as the compound modulation transfer function.
Such techniques are
well suited for use in identifying, generating, or evaluating treatment
shapes.
[0349] Through-focus CMTF curves such as these are useful to evaluating
whether a particular
treatment may be helpful for a particular vision condition. For example, a
treatment shape may be
evaluated with a through-focus CMTF curve to determine whether it might
provide a suitable
bifocal correction. If the through-focus CMTF curve indicates that the
treatment shape provides
CMTF values at or above a threshold (e.g. 0.1) for both distance vision (e.g.
0 D) and near vision
(e.g. 3.0 D), it may be concluded that the treatment shape is a good candidate
for the bifocal
correction. In this case, the treatment shape may generate two peaks on the
through-focus CMTF
curve, one peak for distance vision and one peak for near vision. In some
cases, a treatment shape
may provide a through-focus CMTF curve that meets or exceeds the threshold
across an entire
vergence range (e.g. 0 D to 3.0 D), in which case the treatment shape may be
considered to provide
a very desirable outcome.
[0350] Based on an evaluation of FIGS. 51 and 52, it can be concluded that for
the presbyopic
correction shapes (e.g. at noted cpd spatial frequency sets), image quality
for the convolved E is
quite acceptable where the CMTF curve value is greater than about 0.3. Where
the CMTF curve
value is lower than about 0.1, however, the image quality is not as
acceptable.
[0351] When calculating a goal function or merit function, it is possible to
do so with a through-
focus approach. In some cases, it is desirable to obtain an optimized goal
function, which may be
calculated through a set of target distances, or a set of vergence values. For
example, it may be
possible to separate a 3.0 D vergence into 30 bins, and CMTF values can be
obtained for each of
the 30 incremental 0.1 D vergence locations, and the merit or goal function
can be determined
accordingly.
[0352] Table 6 shows the range of vergence below the CMTF threshold, for each
of the shapes
depicted in FIG. 52. As depicted here, the presbyopic correction shape using
polychromatic PSF
provides the least vergence range (about 0.8D) below threshold.
Table 6
CMTF threshold Vergence Range below CMTF Threshold
Diffraction Limited Monochromatic PSF Polychromatic PSF
0.1 0.3 D to 3 D 0.2 D to 1.2 D 0.5 D to 1.3 D
(total: 2.7 D) (total: 1.0 D) (total: 0.8 D)
CMTF threshold Vergence Range above CMTF Threshold
Diffraction Limited Monochromatic PSF Polychromatic PSF
71
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
0.3 0 D to 0.1 D 0 D to 0.2 D and 0 D to 0..3 D
and
(total: 0.1 D) 1.3 D to 1.7 D 1.5 D to 3.0 D
(total: 0.6 D) (total: 1.8 D)
[0353] It is apparent from FIG. 52 that the CMTF for the presbyopic correction
shape using
monochromatic PSF is greater than the CMTF for the presbyopic correction shape
using
polychromatic PSF, at around the 0 D vergence value. It is also apparent that
the CMTF for the
presbyopic correction shape using monochromatic PSF and the presbyopic
correction shape using
polychromatic PSF diverge significantly at around 1.5 D vergence. For vergence
values higher
than 1.5 D, the presbyopic correction shape using polychromatic PSF provides
markedly higher
CMTF values than does the presbyopic correction shape using monochromatic PSF.
[0354] According to embodiments depicted here, CMTF values below 0.1 D
correspond to little
or no image discernibility, whereas CMTF values above 0.3 correspond to good
image
discernibility. Beneficial optical correction surfaces provide good image
discernibility (e.g. CMTF
above threshold) across a large vergence, or across the through-focus range.
As illustrated in
Table 6, with respect to the 0.1 CMTF threshold, the PPSF provides the
narrowest vergence range
(0.8 D) below threshold. And with respect to the 0.3 CMTF threshold, the PPSF
provides the
broadest vergence range (1.8 D) above threshold. Hence, PPSF can be considered
to correspond to
a more beneficial result, because it provides the least vergence range below
0.1 CMTF threshold
(e.g. little image discernibility) and the greatest vergence range above 0.3
CMTF threshold (e.g.
good image discernibility). A CMTF through-vergence curve with values all
above threshold is
considered to provide a beneficial vision result.
[0355] In general, the 0 D vergence value corresponds to distance vision (e.g.
infinity), and the
1.5 D to 3.0 D vergence values (or in some cases, 2.0 D to 2.5 D) correspond
generally to near
vision. For example, 3 diopters corresponds to a viewing distance of about 33
cm, which is
considered a true reading distance, 2 diopters corresponds to a viewing
distance of 0.5 m, and 1
diopter corresponds to a viewing distance of 1.0 m.
[0356] It can be seen from FIG. 52 that the polychromatic point spread
function provides
improved CMTF for near vision across a larger vergence range, while providing
reduced CMTF
for distance vision across a smaller vergence range. Hence, a polychromatic
point spread function
can provide benefits over a monochromatic point spread function in terms of
accuracy, particularly
for near vision. The polychromatic point spread function can also provide
benefits over a
monochromatic point spread function in terms of a wider depth of field, or
greater through-focus
range, for higher CMTF values. For at least these reasons, it has been
discovered that CMTF
72
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
values based on such polychromatic point spread function provide enhanced
features over CMTF
values based on a monochromatic point spread function.
[0357] In some instances, through-focus CMTF values can be compared with a
CMTF threshold
value of 0.1 for purposes of evaluating image quality. In some instances,
through-focus CMTF
values can be compared with a CMTF threshold value of 0.3 for purposes of
evaluating image
quality. According to the embodiments illustrated in FIGS. 51 and 52, a CMTF
value of 0.1 may
be considered a minimum threshold, below which it is difficult or impossible
to discern the
images, and above which may provide satisfactory results for most patients.
Relatedly, a CMTF
value of 0.3 may be considered a sufficient threshold, above which provides
very good results.
Once a threshold is established, evaluations can be made based on the CMTF
values alone (e.g. as
shown in FIG. 52), without relying upon visual inspection of the convolution
images (e.g. as
shown in FIG. 51).
[0358] In addition to the spatial frequency combinations shown in FIGS. 51 and
52,
embodiments of the present invention encompass the use of other spatial
frequency combinations
to generate other CMTF curves. Such through-focus CMTF curves can be compared
with their
corresponding convolved eye chart letters to determine at what level a CMTF
value for a particular
CMTF spatial frequency set can be considered a good threshold for 20/20 letter
discernibility.
[0359] Hence, embodiments of the present invention encompass system and method
for
obtaining acceptable or threshold CMTF values for evaluating visual acuity
based on an input set
of spatial frequencies for an optical system. In one particular embodiment,
the optical system is a
human eye, and a threshold CMTF value of 0.1 for discerning a 20/20 letter E
is obtained based on
input spatial frequencies of 10, 15, 20, 30 cpd. Correlations between the cpd
frequency values and
the threshold CMTF can be based on visual inspection of the convolved eye
chart.
[0360] Such threshold CMTF values can be used for determining whether a
particular shape
design provides an acceptable vision treatment result for a patient. Threshold
CMTF values can be
used for any general shape design, including shapes designed specifically for
a presbyopia
treatment. According to some embodiments, a threshold CMTF value may be
determined by a
surgeon, optionally with feedback provided by a patient, or with computer
models.
[0361] According to some embodiments, it is possible to modify or generate
optimization
algorithms, once a threshold CMTF value is determined. In certain cases,
including some laser or
intraocular lens treatment modalities, multifocal corrections may involve a
compromise between
73
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
distance and near vision. For example, some corrections may provide enhanced
distance vision
characteristics, while other corrections may provide enhanced near vision
characteristics.
[0362] As noted elsewhere herein, in some cases a treatment shape may provide
a through-focus
CMTF curve that meets or exceeds the threshold CMTF across an entire vergence
range (e.g. 0 D
to 3.0 D). Such treatment shapes may provide a true multifocal or omnifocal
correction for a
patient, where the patient has satisfactory vision throughout the vergence
range, at all target
distances. In such cases, the threshold may be considered to be the minimal
acceptable range. In
some cases, a treatment shape may provide a through-focus CMTF curve that
meets or exceeds a
threshold CMTF of 0.3 across an entire vergence range. In some cases, the
threshold CMTF can
have a value within a range from about 0.1 to about 0.3.
Depth Of Field
[0363] In general, treatment shapes based on a polychromatic point spread
function (PPSF) are
better and more accurate than treatment shapes based on a monochromatic point
spread function
(MPSF). For example, the through-focus (or depth of field) for a treatment
shape based on PPSF
is wider than the through-focus for a treatment shape based on MPSF. For
example, as depicted in
Table 6, the vergence range above a 0.3 CMTF threshold is 0.6 D for MPSF and
1.8 D for PPSF
(e.g. 1.8 D > 0.6 D).
Additional Features Of Monochromatic and Polychromatic Point Spread Functions
[0364] Both monochromatic and polychromatic point spread functions can be used
for
simulating and evaluating the effects of optical systems. A MPSF may not
accurately reflect
certain features associated with the human eye, such as the effect of
chromatic aberrations, the
Stiles-Crawford effect, and the retinal response function effect, for example.
A PPSF, however,
may be better suited for capturing such features.
[0365] FIGS. 53A and 53B illustrate a point spread function (PSF) with the use
of
monochromatic and polychromatic models, respectively. These figures show PSF
images for a -
0.12 D myopic eye with 6 mm pupil calculated using the monochromatic and
polychromatic
models. With such a small amount of myopia, this particular eye is considered
to have a visual
acuity that exceeds 20/20 and a crispy, compact PSF. These images correspond
to a point-source
light. For example, the image profile on the focal plane for a point source
can define the point
spread function. However, the monochromatic PSF of FIG. 53A shows a ring type
configuration.
In contrast, the polychromatic PSF of FIG. 53B shows a centrally concentrated
configuration.
74
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
Hence, a polychromatic PSF model may be considered well suited for use with
the optics of the
human eye. FIG. 54 depicts the cross sections of the PSF images of FIGS. 53A
and 53B.
[0366] As shown in FIG. 54, the normalized intensity for the PPSF has a peak
value near the
center, or zero arc minute field of view. In contrast, the normalized
intensity for the MPSF is more
diffused across the field of view, and presents a valley value near the
center, or zero arc minute
field of view. The concentrated peak result associated with PPSF, as compared
with the ring result
associated with MPSF, is evidence that PPSF provides improved results over
MPSF.
[0367] FIGS. 55A and 55B show the cross-sections for point spread functions
with increasing
defocus, using monochromatic and polychromatic models, respectively. As
depicted here, the
range of defocus extends from a diffraction-limited situation (0 defocus) to a
0.200 D (maximum
focusing error), with 0.025D increments disposed therebetween. The PPSF of
FIG. 55B provides
smooth and regular transitions of the observed normalized intensity curve,
when stepping from one
level of defocus to an adjacent level of defocus. In contrast, the MPSF of
FIG. 55A provides
erratic transitions of the observed normalized intensity curve, when stepping
from one level of
defocus to an adjacent level of defocus.
[0368] As additional focusing error is introduced, the polychromatic point
spread function of
FIG. 55B is observed to become less and less crispy (e.g. shallower and
broader peak of
normalized intensity). The monochromatic point spread function of FIG. 55A,
however, is
observed to become wider and wider very quickly initially as additional
focusing error is
introduced, subsequently changing from a peak to a ring, and thereafter
reverting back from a ring
to a peak. This effect can also be seen in FIG. 56, where the curves are re-
normalized.
[0369] FIG. 56 depicts cross sections of point spread functions calculated
using a
monochromatic model with re-normalization. This result is not consistent with
normal human eye
optics, which do not present a monochromatic situation. Instead, the human eye
provides features
such as chromatic aberrations, the retina response, and the Stiles-Crawford
effect. Relatedly,
white light has a broad spectral range, encompassing light rays of many
different wavelengths (e.g.
red, yellow, blue, green, indigo, and violet). These features affect the
realization of the point
spread function. The polychromatic point spread function, as shown in FIGS. 54
and 55B,
provide a more centrally defined zone of normalized intensity, which is more
realistic optically.
Hence, it can be seen that for visual simulation or evaluation, use of a
polychromatic PSF may be
more appropriate than use of a monochromatic PSF. Exemplary techniques for
implementing the
point spread function are discussed elsewhere herein, as well as in previously
incorporated
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
12/649,575, filed December 30, 2009, and Guang-ming Dai, Wavefront Optics for
Vision
Correction (SPIE Press, 2008), the contents of which are incorporated herein
by reference.
[0370] According to embodiments of the present invention, polychromatic
aberrations can be
used to calculate point spread functions. What is more, polychromatic point
spread functions can
be used to convolve resolution targets.
[0371] The use of polychromatic point spread functions can provide an
improvement in accuracy
as compared with the use of monochromatic point spread functions. This can be
the case with the
use of polychromatic aberrations, as compared with monochromatic aberrations,
for the calculation
of the point spread function. This can also be the case with the use of
monochromatic point spread
functions, as compared with polychromatic point spread functions, for
convolving images.
[0372] As describe elsewhere herein, it is possible to use monochromatic point
spread functions
as well as polychromatic point spread functions. Once a point spread function
has been
determined, it is possible to evaluate acuity.
[0373] FIG. 57 illustrates a method 5700 of evaluating an image quality
provided by a vision
treatment shape according to embodiments of the present invention. As shown
here, method 5700
includes obtaining a plurality of through-focus compound modulation transfer
function (CMTF)
values for the vision treatment shape, as depicted by step 5710, comparing the
plurality of through-
focus CMTF values to a CMTF threshold value, as depicted by step 5720, and
evaluating the
image quality based on the comparison between the through focus CMTF values
and the CMTF
threshold value, as depicted by step 5730.
[0374] FIG. 58 illustrates a method 5800 of determining a compound modulation
transfer
function (CMTF) threshold value for a CMTF spatial frequency set. As shown
here, method 5800
includes obtaining a plurality of through-focus CMTF values for a vision
treatment shape, where
the CMTF values are based on the CMTF spatial frequency set, as depicted by
step 5810,
obtaining a plurality of through-vergence convolved images based on the vision
treatment shape
and a point spread function, as depicted by step 5820, and determining the
CMTF threshold value
for the CMTF spatial frequency set based on the plurality of through-focus
CMTF values and the
plurality of convolved images, as depicted by step 5830.
76
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
Goal Functions Having Multiple Metrics or Parameters
[0375] Treatment modalities for presbyopia and other vision conditions can be
based on goal
functions having multiple metrics or parameters. For example, composite
optical metrics may
include various combinations of metrics selected from a Strehl ratio, a
modulation transfer
function (MTF), an encircled energy, a compound modulation transfer function
(CMTF), a point
spread function (PSF), a volume under MTF surface (VMTF), a contrast
sensitivity (CS), and the
like. In this way, combinations of multiple optical metrics for the
calculation of a goal function or
optimizer value can be used in treatments such as intraocular lenses, contact
lenses, spectacle
lenses, refractive surgery and other laser photoalteration procedures, corneal
inlays, conductive
keratoplasty procedures, and the like.
[0376] According to some embodiments, composite optical metrics may include
linear
combinations of individual optical metrics. In certain embodiments, a
composite optical metric
may include individual weighting coefficients or functions associated with
respective individual
parameters of the composite optical metric. For example, a goal function or
composite optical
metric may be represented by the following formula,
M(1) = kiM ,(1)
i=1
where k, is a weighting coefficient or function for an ith optical metric
M,(1), n represents the
number of individual metrics or parameters, l is the vergence, and m(/) is the
composite metric.
The weighting function may be a weighting coefficient (a number, or a
constant), or it may be a
function, such as a two-dimensional function. Relatedly, an individual metric
of the composite
metric may be two-dimensional. According to some embodiments, it is possible
to treat the
weighting function as apodization functions to eliminate certain spatial
frequency information as
needed or desired. In some instances, a weighting function can be represented
as k, (p, 0) in a
polar coordinate system. In some instances, a weighting function can be
represented as k, (x,y) in
a Cartesian coordinate system. According to some embodiments, a weighting
function may be
represented by a spatial function.
[0377] Where an optical metric is a single number (e.g. Strehl Ratio) then it
may be desirable
that the weighting function also be a number (e.g. as opposed to a two
dimensional function).
Where an optical metric is in the frequency domain (e.g. CMTF) then it may be
desirable that the
weighting function also be in the frequency domain, or optionally as a
constant. Where an optical
metric is in the spatial domain (e.g. PSF or encircled energy) then it may be
desirable that the
77
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
weighting function also be in the spatial domain, or optionally as a constant.
Both frequency
domain and spatial domain metrics can be expressed in two dimensional
representations, such as k,
(p, 0) in a polar coordinate system or k, (x,y) in a Cartesian coordinate
system.
[0378] An optical metric may be represented by a spatial function. For
example, optical metrics
such as a two dimensional point spread function may be represented in normal
space (x,y), and
optical metrics such as an optical transfer function or compound modulation
transfer function may
be represented in Fourier space or frequency domain (kx, ky). In some
embodiments, optical
metrics represented in normal or real space may be represented in distance
units, such as
millimeters or microns. In some embodiments, optical metrics represented in
the frequency space
may be expressed in cycles per degree (e.g. an indication of oscillation
behavior). In some
instances, an optical metric may not be represented by a spatial function. For
example, optical
metrics such as a Strehl Ratio may be represented as a number or a constant.
When summing or
combining optical metrics, it may be helpful to have the optical metrics be
represented in the same
space or expressed in similar units. In some cases, it may be possible to
convert an optical metric
from one space or representation to another, so that it can conveniently be
combined with other
optical metrics. For example, a composite optical metric that combines Strehl
Ratio and
Compound Modulation Transfer Function may be straightforward, because Strehl
Ratio can be
expressed as a single number. In comparison, a composite optical metric that
combines Point
Spread Function and Compound Modulation Transfer Function may involve a
conversion of one
of the individual parameters, so that both parameters are represented in the
same space. In some
embodiments, a composite optical metric may include parameters that are
originally in the Fourier
or frequency domain. According to some embodiments, a weighting function may
be normalized.
In some cases, a weighting function may not be normalized. Goal functions or
composite optical
metrics, or individual components thereof, can be minimized or maximized as
discussed elsewhere
herein. In some instances, optimizer values may be used, where the optimizer
value is minimized
(e.g. determining a minimum value in two dimensional space) such that the
optical metric is
maximized. In some cases, an optimizer value can correspond to an optical
metric, as the mean of
the reciprocal of the optical metric.
[0379] In certain embodiments, a goal function or composite optical metric may
include a
CMTF parameter as one of the individual parameters of the composite. For
example, a
combination may include CMTF with Strehl ratio, or CMTF with encircled energy.
The following
equation represents a composite optical metric that includes CMTF and Strehl
ratio.
m(/)= k1CMTF(1)+ k2SR(1)
78
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0380] Similarly, the following equation represents a composite optical metric
that includes
CMTF and visual Strehl ratio,
m(/)= kiCMTF (1) + k2VSR(1)
[0381] where VSR(1) stands for visual Strehl ratio. In some embodiments,
composite optical
metrics disclosed herein can include any of the individual metrics described
in Thibos, et al,
"Accuracy and precision of objective refraction from wavefront aberrations,"
J. Vision 4, 320-351
(2004), the content of which is incorporated herein by reference.
[0382] Vergence Weighting And Testing Points
[0383] For the treatment or correction of presbyopia or other vision
conditions, different
individuals may have different needs or desires with regard to their vision.
For example, people
such as accountants and lawyers, whose day to day professional activities may
include reading
documents, may require or desire the very best near vision and may be willing
to sacrifice some
intermediate and distance vision. On the other hand, people such as truck
drivers and golfers,
whose professional activities may benefit from crystal-clear far vision, may
require or desire the
best distance vision and may be willing to sacrifice intermediate vision and
near vision. Further,
engineers who spend large amounts of time viewing a computer screen may wish
to optimize their
intermediate vision and may be willing to sacrifice some near vision and
distance vision.
[0384] In the context of vision treatment and correction modalities, the term
optical vergence
can refer to certain vision testing conditions, for example calculated as the
reciprocal of the testing
or viewing distance in meters. Such testing conditions can also be referred to
as a testing points.
According to some embodiments of the present invention, optimization of an
optical shape may
involve factoring in such testing point preferences for individual
customization.
[0385] FIG. 59 depicts aspects of an exemplary method 5900 for treating a
vision condition of
an eye in a particular patient. As shown here, the method includes receiving a
vision requirements
specification selected for the particular patient, as indicated by step 5910.
As discussed elsewhere
herein, the vision requirements specification can include a first weighting
value for a first viewing
distance within a vergence range and a second weighting value for a second
viewing distance
within the vergence range. The method also includes determining an optical
surface shape for the
particular patient, as indicated by step 5930. The optical surface shape can
be based on the vision
requirements specification and an optical metric 5920. Further, the method can
include treating
the vision condition of the eye of the particular patient by providing a
treatment to the patient, as
indicated by step 5940. The treatment can include a shape that corresponds to
the optical surface
79
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
shape. Relatedly, embodiments of the present invention encompass systems and
methods for
determining a procedure for treating a vision condition of an eye of a
particular patient based on an
optical surface shape. In some cases, a procedure can include ablating a
corneal surface or
subsurface of the eye of the particular patient to provide a corneal surface
shape that corresponds
to the optical surface shape. In some cases, a procedure can include providing
the particular
patient with a contact lens or a spectacle lens having a shape that
corresponds to the optical surface
shape. In some cases, a procedure can include providing the particular patient
with an intra-ocular
lens having a shape that corresponds to the optical surface shape.
[0386] Relatedly, FIG. 60 depicts aspects of an exemplary method for
generating an optical
surface shape for use in treating a vision condition of an eye in a particular
patient. As shown
here, the method includes receiving a vision requirements specification
selected for the particular
patient, as indicated by step 6010. As discussed elsewhere herein, the vision
requirements
specification can includes a first weighting value for a first viewing
distance within a vergence
range and a second weighting value for a second viewing distance within the
vergence range. The
method also includes generating the optical surface shape for the particular
patient, as indicated by
step 6030. The optical surface shape can be based on the vision requirements
specification and an
optical metric 6020.
[0387] FIG. 61 depicts aspects of a vision requirements specification 6100,
according to
embodiments of the present invention. The vision requirements specification
can include a first
weighting value V1 for a first viewing distance D1 within a vergence range
6110 and a second
weighting value V2 for a second viewing distance D2 within the vergence range.
In some cases,
the first viewing distance can correspond to a near vision viewing distance
6120 (or near vision
viewing distance range), an intermediate vision viewing distance 6130 (or
intermediate vision
viewing distance range), or a distance vision viewing distance 6140 (or
distance vision viewing
distance range). Similarly, in some cases, the second viewing distance can
correspond to a near
vision viewing distance 6120 (or near vision viewing distance range), an
intermediate vision
viewing distance 6130 (or intermediate vision viewing distance range), or a
distance vision
viewing distance 6140 (or distance vision viewing distance range). According
to some
embodiments, the first weighting value V1 can be different from the second
weighting value V2,
and the first viewing distance D1 can be different from the second viewing
distance D2. In some
cases, the first weighting value V1 can be greater than the second weighting
value V2. In some
cases, the first viewing distance D1 is less than the second viewing distance
D2. In some cases,
the first viewing distance D1 is greater than the second viewing distance D2.
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0388] In some cases, as depicted in FIG. 61, the first weighting value V1 can
be less than the
second weighting value V2. Hence, the vision requirements specification 6100
depicted here may
be suitable for an individual who needs or desires excellent distance (or far)
vision, and where
good near vision is not as important. In contrast, FIG. 62 depicts a vision
requirements
specification 6200 that is suitable for an individual who needs or desires
excellent near and
intermediate vision, and where distance vision is not as important. As shown
here, the weighting
values corresponding to near and intermediate distances are greater in value,
as compared to the
weighting value corresponding to far distance. In some embodiments, the
weighting values
corresponding to intermediate and far distances are greater in value, as
compared to the weighting
value corresponding to near distance. In some embodiments, the weighting
values corresponding
to near and far distances are greater in value, as compared to the weighting
value corresponding to
intermediate distance. In some cases, weighting values corresponding to
different distances (e.g.
near and far) can be balanced to have the same value.
[0389] In some cases, weighting values corresponding to different distances
(e.g. near and far)
can be unbalanced so as to have the different values.
[0390] In some cases, weighting values can be selected or customized according
to a particular
patient preference or treatment protocol. As an example, for a patient who
works as an engineer,
the weighting can be 0.5 for near, 2.0 for intermediate (e.g. at 0.5 meters or
a range including 0.5
meters), 0.5 for distance, or the like. Such a weighting regime can be well
suited for use for
treating an individual who desires good vision for viewing a computer screen
(e.g. higher
weighting values for the viewing distance). The weighting values for other
occupations may vary.
For example, for truck drivers, the weighting can be 0.5 for near, 0.5 for
intermediate, and 2.0 for
distance. For lawyers, the weighting can be 2.0 for near, 0.5 for
intermediate, and 0.5 for distance.
The weighting values can be provided in a normalized format (e.g. the values
have a mean of 1.0).
In some cases, the weighting can correspond to a linear function of viewing
distance (or vergence),
or to a nonlinear function, depending on the need or desired treatment.
[0391] According to exemplary embodiments of the present invention, the
weighting values for
different viewing distances can be used in conjunction with an optical metric
for evaluating or
determining an optical surface shape (which may correspond to a target or a
treatment shape), for
example based on a merit function or optimizer value. As shown in FIG. 63, a
merit function
6310 for a target or treatment shape can be determined based on an optical
metric value for the
shape at the various viewing or testing distances, for example 6320a, 6320b,
and 6320c, as applied
to the various weighting values for the various viewing or testing distances,
for example [V1, D11,
81
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[V2, D21, and [V3, D31. In this way, a merit function can capture information
about the optical
surface shape, where the information varies as a function of 1 (e.g. CMTF
values at different
distances/vergence), and the optical metric information can be modified
according to weighting
values for various distances/vergences.
[0392] Optical metrics such as a compound modulation transfer function (CMTF)
can provide a
measure of optical quality for the shape throughout a range of vergence or at
different spatial
distances (/). Exemplary optical metrics (e.g. such as composite optical
metrics) that can be used
in conjunction with embodiments of the present invention are discussed in US
Patent Publication
No. 2014/0016091, the content of which is incorporated herein by reference. In
some cases, an
optical metric can include a compound modulation transfer function (CMTF)
parameter having a
combination of modulation transfer functions (MTF' s) at a plurality of
distinct frequencies.
[0393] In some cases, the optimizer value or merit function 6310 for an
optical surface shape can
be calculated based on various parameters associated with the optical metric.
[0394] For example, if the distance values are selected for every 0.1 Diopter
or 0.1 meter and the
vergence range is 3.0 Diopters, then there will be 30 data points or values to
be considered (e.g.
one optical metric value for each of the distance values). Based on those 30
values, it is possible
to calculate the mean, standard deviation, and peak-to-valley for the optical
metric.
[0395] The merit function value may be calculated as:
(1.-Fo-)(1.+16')
f = ________________________________________________________________________
(Eq. 1)
where -0), a, and are the mean, standard deviation, and peak-to-valley
(maximum to minimum),
respectively, of the optical metric for CMTF or other metrics like Strehl
Ratio (SR), modulation
transfer function (MTF), point spread function (PSF), encircled energy (EE),
MTF volume or
volume under MTF surface (MTFV), contrast sensitivity (CS), or various
combinations thereof.
Exemplary metrics are described in US Patent Application No. 13/732,124 filed
December 31,
2012, the content of which is incorporated herein by reference.
[0396] According to some embodiments, once an optical metric is defined, a
merit function can
be constructed so that a function minimization algorithm can be applied to
maximize the optical
metric. In some cases, the merit function is inversely proportional to the
optical metric. In some
cases, it is possible to maximize the optical metric while ensuring the
optical metric curve over the
range does not fluctuate excessively. An exemplary merit function or optimizer
value is provided
by Eq. 1.
82
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0397] As noted above, different weighting values can be associated with the
different
distances/vergence. The different weighting values can be applied to the
optical metric values
when calculating the merit function. Hence, whereas Eq. 1 in some embodiments
uses the mean
OW of the optical metric over the entire vergence range, it is possible to
construct a merit function
that replaces the mean Q(/) with the following expression:
')=
-
'=1
1=1
(Eq. 2)
[0398] where s, is the weighting coefficient or value for the given testing or
viewing distance
(vergence). This expression for Q(/) can be substituted in the merit function
calculation depicted
in Eq. 1. The optical metric C(m) can be any desired optical metric (e.g.
CMTF), (m) can be the
number of spatial frequencies (e.g. for calculating MTF), and (/) can refer to
the vergence.
[0399] The summation I in the denominator indicates that the weighting
coefficients or values s,
are summed. Here, different testing distances can correspond to different
viewing distances, which
can be throughout the vergence range (i = 1 to t). At a distance of infinity,
the vergence can be
considered as zero. As indicated here, t can represent the number of samples.
For example, for t =
10, each individual sample can represent 1/10 of the range. Hence, t can refer
to the degree of
granularity for which the metrics are calculated. In some cases, the sampling
points can
correspond to a linear distribution. In some cases, the sampling points can
correspond to a bell
curve distribution. In some cases, the sampling points can correspond to a
quadratic distribution.
Where the distribution is non-linear, it may be desirable to use a greater
number of sampling
points, according to some embodiments.
[0400] For example, certain approaches for the treatment of presbyopia and
other vision
conditions can involve the use of a shape that is optimized based on the
optimizer value as a
function of an optical metric such as Strehl ratio, modulation transfer
function (MTF), encircled
energy, compound modulation transfer function (CMTF), and the like. Aspects of
such optical
metrics are disclosed in U.S. Patent Nos. 7,320,517; 7,475,986; 7,862,170;
8,029,137; and
8,220,925, the contents of which are incorporated herein by reference. Related
vision treatment
modalities may include the use of one or more combinations of multiple optical
metrics for the
calculation of an optimizer value, for example as described in U.S. Patent
Publication No.
2014/0016091, the content of which is incorporated herein by reference.
83
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0401] In some cases, as illustrated in FIGS. 64A and 64B, first and second
weighting values
(e.g. V1, V2) can be members of a weighting value distribution (e.g. 6410a,
6410b) that is linear
across a vergence range that includes first and second viewing distances (e.g.
D1, D2).
[0402] As discussed elsewhere herein, either linear or nonlinear functions can
be used for a
weighting value distribution. For example, quadratic functions, quartic
functions, Gaussian
distribution functions, and the like, may be used.
[0403] In some cases, as illustrated in FIGS. 65A, 65B, 65C, and 65D, first
and second
weighting values (e.g. V1, V2) can be members of a weighting value
distribution (e.g. 6510a,
6510b, 6510c, 6510d) that is non-linear across a vergence range that includes
first and second
viewing distances (e.g. D1, D2).
[0404] FIGS. 66A and 66B depict aspects of various weighting value
distributions (e.g. 6610a,
6610b) according to embodiments of the present invention. As shown in FIG.
66A, a weighting
value distribution 6610a can be defined by a function having one or more peaks
(e.g. 6620a,
6630a) within a vergence range. In some cases, the weighting value
distribution 6610a can be
defined by two sub-distributions or sub-functions 6612a, 6614a. As shown in
FIG. 66B, a
weighting value distribution 6610b can be defined by a step function having
one or more steps
(e.g. 6620b, 6630b, 6640b) within a vergence range.
[0405] According to some embodiments, the weighting value distribution
depicted in FIG. 67B
is preferred over the weighting value distribution depicted in FIG. 67A, for
example because of
lower peak weighting value, and broader distribution across vergence range.
Put another way, a
more gentle change in the weighting function or weighting value distribution
can provide less
fluctuation of the values, thereby reducing the possibility of having too low
or insufficient
weighting for a given vergence. For example, if a 2.8 weight is assigned for
intermediate and 0.1
weights are assigned for near and distance, respectively, then both near and
distance vision may
not be sufficient, and the patient may not effectively be able to read and see
distance objects. As
noted elsewhere herein, weighting values can be provided in a normalized
format (e.g. the values
have a mean of 1.0).
[0406] According to some embodiments, a scaling operation can be applied.
Accordingly, the
ratio or relationship between different weighting values for different
distances may be more
relevant that the magnitude of the individual weighting values themselves. In
some cases, it is
possible to use a multiplication scaling factor to compare to the weights at
different distances
(vergence). For example, a weighting at intermediate can be 2 times (double) a
weighting at near
84
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
and far, or a weight at far can be 3 times (triple) a weight at near and 2
times (double) a weight at
intermediate.
[0407] FIGS. 68-71 provide example distance, intermediate, and near vision
experienced by an
eye pre- and post-treatment according to some embodiments of the present
invention. For
example, FIGS. 68A, 68B, and 68C illustrate example distance, intermediate,
and near vision
experienced by an eye without any vision correction, respectively. In
particular, FIG. 68A
illustrates an example distance view down a street, FIG. 68B illustrates an
example intermediate
view of a computer screen, and FIG. 68C illustrates an example near view of
news text. As can be
seen in each of FIGS. 68A-68C, each of distance, intermediate, and near vision
experienced by the
eye will be out of focus or otherwise blurry without any vision correction.
[0408] FIGS. 69A, 69B, and 69C illustrate example distance, intermediate, and
near vision
experienced by an eye corrected with an optimization or emphasis for near
vision viewing
distances with less emphasis on far and intermediate viewing distances,
respectively. Put in
another way, the distance, intermediate, and near viewing distances are each
corrected for,
however the distance and intermediate viewing distances are corrected with
less optimization or
emphasis compared to the optimization or emphasis for near vision viewing
distances. As
illustrated in FIG. 69C, the example near view of the news text is now in
focus with the
optimization for near vision correction. The example intermediate view of the
computer screen in
FIG. 69B for the eye corrected with optimization for near vision is more in
focus or less blurry
than the intermediate view of the computer screen shown in FIG. 68B for the
eye without
correction, but is still slightly out of focus compared to the example near
view of the news text
shown in FIG. 69C. Lastly, the example distance view of the street in FIG. 69A
for the eye
corrected with the optimization for near vision distance only is more in focus
or less blurry than
the example distance view of the street in FIG. 68A for the eye without
correction, but is also out
of focus and more out of focus than the example intermediate view of the
computer screen in FIG.
69B for the eye corrected with optimization for near vision correction only.
[0409] FIGS. 70A, 70B, and 70C illustrate example distance, intermediate, and
near vision
conditions experienced by an eye corrected with an optimization or emphasis on
both intermediate
and near viewing distances and with less of an emphasis on far viewing
distances, respectively.
The optimization for both intermediate and near viewing distance correction
may correspond to the
vision requirements specification graph shown in FIG. 62, where the weighting
values
corresponding to near and intermediate distances are greater in value, as
compared to the
weighting value corresponding to far distance. Put in another way, the
distance, intermediate, and
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
near viewing distances are each corrected for, however the far viewing
distances are corrected with
less optimization or emphasis compared to the optimization or emphasis for
both intermediate and
near vision viewing distances. The weighting values for intermediate and near
vision viewing
distances may be the same or may be different in some embodiments. As shown in
FIG. 70C, the
example near view of the news text when the eye is corrected with optimization
or emphasis for
both intermediate and near viewing distances is less in focus compared to the
example near view
of the news text shown in FIG. 69C when the eye is corrected with optimization
for near vision
viewing distances only; however, the example near view of the news text when
the eye is corrected
with optimization for both intermediate and near viewing distances in FIG. 70C
is still more in
focus than the example near view of the text shown in FIG. 68C, when the eye
is without any
vision correction. While the example near view of the text is slightly less in
focus when the eye is
corrected with optimization for both intermediate and near viewing distances
compared to when
the eye is corrected with optimization for near vision viewing distances only,
the example
intermediate view of the computer screen shown in FIG. 70B where the eye is
corrected with
optimization for both intermediate and near viewing distances is slightly more
in focus or less
blurry compared to the example intermediate view of the computer screen shown
in FIG. 69B
where the eye is corrected with optimization for near viewing distances only
(i.e., less emphasis
for far and intermediate viewing distances). Further, as shown in FIG. 70A,
the example distance
view of the street for the eye corrected with emphasis for both intermediate
and near vision is more
out of focus that the example intermediate view of the computer screen in FIG.
70B for the eye
corrected with optimization for both intermediate and near vision viewing
distances only, but is in
more focus or otherwise less blurry than the example distance view of the
street in FIG. 68A for
the eye without any correction. The example distance view of the street for
the eye corrected with
optimization for both intermediate and near vision as shown in FIG. 70A may
be, in some
instances, of similar quality as the example distance view of the street for
the eye with
optimization for near vision correction only shown in FIG. 69A.
[0410] FIGS. 71A, 71B, and 71C illustrate example distance, intermediate, and
near vision
conditions experienced by an eye corrected with optimization or emphasis for
both distance and
intermediate viewing distances and less emphasis on near viewing distances,
respectively. The
optimization for both distance and intermediate viewing distance correction
may be associated
with a vision requirements specification where the weighting values
corresponding to distance and
intermediate are greater in value, as compared to the weighting value
corresponding to near
distance. As illustrated in FIG. 71A, the example distance view of the street
for the eye corrected
with optimization for both distance and intermediate viewing distances is more
in focus than the
86
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
example distance view of the street for the eye corrected with optimization
for near viewing
distances only as shown in FIG. 69A and is more in focus than the example
distance view of the
street for the eye corrected with optimization for both intermediate and near
viewing distances as
shown in FIG. 70A. Further, the example intermediate view of the computer
screen experienced
by the eye corrected with optimization for both distance and intermediate
viewing distances as
shown in FIG. 71B is more in focus than the example intermediate view of the
computer screen
experienced by the eye corrected with optimization for near viewing distances
only as shown in
FIG. 69B. In some embodiments, the intermediate view of the computer screen
for the eye
corrected with optimization for both distance and intermediate viewing
distances as shown in FIG.
71B may be comparable to the example intermediate view of the computer screen
for the eye
corrected with optimization for both intermediate and near vision shown in
FIG. 70B. As shown
in FIG. 71C, the example near view of the news text for the eye corrected with
optimization for
both distance and intermediate viewing distances may be more blurry than the
example near view
of the news text experienced by the eye corrected with optimization for both
intermediate and near
distances shown in FIG. 70C and by the eye corrected with optimization for
near distances only
shown in FIG. 69C. While the example near view of the news text for the eye
corrected with
optimization for both distance and intermediate viewing distances may be more
blurry than the
example new views of the news text experienced by the eye corrected with
optimization for near
distances or corrected with optimization for both intermediate and near
distances, the example near
view of the news text for the eye corrected with optimization for both
distance and intermediate
viewing shown in FIG. 71C may nevertheless be less blurry or more in focus
than the example
near view of the news text experienced by the eye that has no correction as
shown in FIG. 68C.
[0411] In further embodiments, a weighting function may not be applied to
distance/far,
intermediate, and near vision specification. Instead, the correction may be
based on a function that
applies to a portion of or the entire range of the vision field or vergence
range. As an example
using target distance, the weighting function may have values at various
target distances. For
example, the weighting function may have values associated with one or more of
100 m, 10 m, 5
m, 4 m, 3 m, 2 m, 1 m, 50 cm, 40 cm, 30, cm, 20 cm, etc. As another example
using vergence
range, the weighting function may have values at various vergences. For
example, the weighting
function may have values associated with one or more of OD, 0.2D, 0.4D, 0.6D,
0.8D, 1D, 1.5D,
2D, 2.5D, 3D, 3.5D, 4D, etc. Therefore, the application of the vergence
weighting is more general
than just 2 or 3 target distances. This idea may be applied to both eyes
similarly or differently.
87
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0412] It should understood that these example views are provided by way of
illustration only
and that eye corrections may be customized with preferred optimization or
emphasis in many other
manners per the embodiments disclosed herein. For example, an eye may be
corrected with an
emphasis for far viewing distances only or with an emphasis for intermediate
distances only.
Additionally as set forth above, in some embodiments, the weighting values
corresponding to near
and far distances may be greater in value, as compared to the weighting value
corresponding to
intermediate distance. In some cases, weighting values corresponding to
different distances (e.g.
near and far) can be balanced to have the same value. Additionally, it should
be appreciated that
the same correction may be applied to both eyes of a patient or different
corrections with different
emphases may be applied to each eye to provide additional treatment
customization. For example,
one eye may be optimized for distance viewing while the other eye may be
optimized for near
viewing distances (e.g., monovision). Alternatively, one eye may be optimized
for distance, and
the other eye may be optimized for both near and intermediate viewing
distances (e.g., FIGS.
70A-70C). Still further, one eye may be corrected with an emphasis for near
viewing distances
(e.g., FIGS. 69A-69C), and the other eye may be corrected with an emphasis for
both distance and
intermediate viewing distances (e.g., FIGS. 71A-71C). Thus, in some
embodiments, one eye may
be optimized for a particular vergence weighting function and the other eye
may be corrected for
another particular vergence weighting function. For example, one eye may be
corrected with an
emphasis for both distance and intermediate viewing distances (e.g., FIGS. 71A-
71C) and the
other eye may be corrected with an emphasis for both intermediate and near
viewing distances
(e.g., FIGS. 70A-70C). Further, it some embodiments, a correction applied to
one eye may be
customized based on eye dominance. Also, it should be appreciated that the
patient eye may be
corrected with a weighting function having values associated with a number of
target distances or
vergences. With such an application the vergence weighting may be more general
than just 2 or 3
target distances or vergence ranges.
[0413] Accordingly, a method for treating a vision condition of a particular
patient may be
provided in some embodiments. The method may include receiving a vision
requirement
specification selected for the particular patient. The vision requirement
specification may include
a first weighting function for a first viewing distance within a first
vergence range for the first eye
and a second weighting function for a second viewing distance within a second
vergence range for
a second eye. The method may further include determining an optical surface
shape for each eye
of the particular patient. The optical surface shape may be based on the
vision requirements
specification of the particular eye and an optical metric. Thereafter, the
method may include
treating the vision condition of the eyes of the particular patient by
providing a treatment to each
88
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
eye of the patient. The treatment may include a shape that corresponds to the
optical surface
shape.
[0414] In some embodiments, the first weighting function includes a first
weighting value
associated with a far distance and a second weighting value associated with a
near distance. The
first weighting value of the first weighting function may be greater than the
second weighting
value of the first weighting function. The second weighting function may
include a first weighting
value associated with the far distance and a second weighting value associated
with the near
distance. The second weighting value may optionally be greater than the first
weighting value.
[0415] In further aspects, the first weighting function may include a first
weighting value
associated with a far distance, a second weighting value associated with an
intermediate distance,
and a third weighting value associated with a near distance. The first
weighting value of the first
weighting function may be greater than the second and third weighting value of
the first weighting
function. The second weighting function may include a first weighting value
associated with the
far distance, a second weighting value associated with the intermediate
distance, and a third
weighting value associated with the near distance. The first weighting value
of the second
weighting function may be less than the second and third weighting values of
the second weighting
function in some embodiments. Optionally, the second and third weighting
values of the second
weighting function may be the same.
[0416] In certain aspects, the first weighting function may include a first
weighting value
associated with a far distance, a second weighting value associated with an
intermediate distance,
and a third weighting value associated with a near distance. The third
weighting value of the first
weighting function may be greater than the second and third weighting value of
the first weighting
function. The second weighting function includes a first weighting value
associated with the far
distance, a second weighting value associated with the intermediate distance,
and a third weighting
value associated with the near distance. The third weighting value of the
second weighting
function may be less than the first and second weighting values of the second
weighting function.
Optionally, the first and second weighting values of the second weighting
function may be the
same. Thus, in some embodiments, the first vergence weighting function and the
second vergence
weighting function may be different.
[0417] As discussed elsewhere herein, embodiments of the present invention
encompass systems
and methods that involve determining an optical surface shape for a particular
patient (e.g. where
the optical surface shape is based on a vision requirements specification and
an optical metric), and
treating a vision condition of an eye of the particular patient by providing a
treatment to the
89
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
patient, where the treatment is based a shape that corresponds to the optical
surface shape.
Relatedly, in some cases exemplary systems and methods can involve generating
a treatment shape
for treating the eye of the patient, where the treatment shape is based on the
optical surface shape.
In some cases, the treatment shape can be an intraocular lens treatment shape.
In some cases, the
treatment shape can be a contact lens shape. In some cases, the treatment
shape can be a spectacle
lens shape. In some cases, the treatment shape can correspond to a laser
ablation or
photodisruption target shape.
[0418] Each of the above calculations may be performed using a computer or
other processor
having hardware, software, and/or firmware. The various method steps may be
performed by
modules, and the modules may comprise any of a wide variety of digital and/or
analog data
processing hardware and/or software arranged to perform the method steps
described herein. The
modules optionally comprising data processing hardware adapted to perform one
or more of these
steps by having appropriate machine programming code associated therewith, the
modules for two
or more steps (or portions of two or more steps) being integrated into a
single processor board or
separated into different processor boards in any of a wide variety of
integrated and/or distributed
processing architectures. These methods and systems will often employ a
tangible media
embodying machine-readable code with instructions for performing the method
steps described
above. Suitable tangible media may comprise a memory (including a volatile
memory and/or a
non-volatile memory), a storage media (such as a magnetic recording on a
floppy disk, a hard disk,
a tape, or the like; on an optical memory such as a CD, a CD-R/W, a CD-ROM, a
DVD, or the
like; or any other digital or analog storage media), or the like.
[0419] As the analytical solutions described herein some or all of these
method steps may be
performed with computer processors of modest capability, i.e., a 386 processor
from IntelTM may
be enough to calculate the Zernike coefficients, and even 286 processor may be
fine. Scaling of
Zernike coefficients was described by Jim Schweigerling, "Scaling Zernike
Expansion Coefficients
to Different Pupil Sizes," J. Opt. Soc. Am. A 19, pp 1937-1945 (2002). No
special memory is
needed (i.e., no buffers, all can be done as regular variables or using
registers). Also, it can be
written in any of a wide variety of computer languages, with the exemplary
embodiment
employing C++. This exemplary embodiment comprises code which performs the
Zernike
coefficient calculation, shape combination (combining a regular aberration
treatment prescription
as well as the presbyopia shape), and provides graphical output for reporting
purpose. It was
written in C++ with Borland C++ BuilderTM 6, and it is run with a laptop of
1.13GHz CPU having
512Mb of memory.
CA 02973345 2017-07-07
WO 2016/111851 PCT/US2015/067363
[0420] As noted above, a variety of output data can be generated by the
systems and methods of
the present invention. Such outputs may be used for a variety of research,
comparison, prediction,
diagnostic, and verification operations. The outputs may be evaluated
directly, or they may be
used as input into the system for further analysis. In some embodiments, the
outputs will be used
to model the effect of an ocular treatment prior to application. In other
embodiments, the outputs
will be used to evaluate the effect of an ocular treatment after application.
The outputs may also
be used to design ocular treatments. Relatedly, it is possible to create
treatment tables based on
outputs of the instant invention.
[0421] While the exemplary embodiments have been described in some detail, by
way of
example and for clarity of understanding, those of skill in the art will
recognize that a variety of
modification, adaptations, and changes may be employed. Hence, the scope of
the present
invention should be limited solely by the claims.
91
