Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEMS FOR OPTHALMIC MEASUREMENTS AND LASER SURGERY AND SYSTEMS
FOR SURGICAL PLANNING
BASED THEREON
CROSS-REFERENCE
[0001] This application is a continuation-in-part of U.S. Patent
Application No.
14/327,839, filed July 10, 2014, which claims the benefit of priority to U.S.
Provisional Patent
Application No. 61/858,445, filed on Jul. 25, 2013, which is related to the
following patent
applications: U.S. Patent Application No. 12/048,182, filed Mar. 3, 2008,
entitled "METHOD
AND APPARATUS FOR CREATING INCISIONS TO IMPROVE INTRAOCULAR LENS
PLACEMENT," U.S. Patent Application No. 12/048,186, filed Mar. 13, 2008,
entitled
"METHOD AND APPARATUS FOR CREATING OCULAR SURGICAL AND RELAXING
INCISIONS," and U.S. Patent Application No. 61/722,064, filed Nov. 2, 2012,
entitled "LASER
EYE SURGERY SYSTEM CALIBRATION," the entirety of all of which are hereby
incorporated by reference.
BACKGROUND
[0002] The eyes of many patients have structural features that result in
less than ideal
optical characteristics. At least some patients have refractive errors of the
eye such as myopia,
hyperopia and astigmatism. These refractive conditions can be corrected with
spectacles or
contact lenses. Alternatively, the cornea of the patient's eye can be reshaped
surgically to
provide the needed optical correction. Eye surgery has become commonplace with
some patients
pursuing it as an elective procedure to avoid using contact lenses or glasses
to correct refractive
problems, and others pursuing it to correct adverse conditions such as
cataracts. And, with
recent developments in laser technology, laser surgery is becoming the
technique of choice for
ophthalmic procedures. The reason eye surgeons prefer a surgical laser beam
over manual tools
like microkeratomes and forceps is that the laser beam can be focused
precisely on extremely
small amounts of ocular tissue, thereby enhancing accuracy and reliability of
the procedure.
These in turn enable better wound healing and recovery following surgery.
Surgical approaches
for reshaping the cornea include laser assisted in situ keratomileusis
(hereinafter "LASIK"), and
photorefractive keratectomy (hereinafter "PRK").
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[0003] Besides refractive errors, some patients may have an irregularity
of the cornea of
eye such as irregular astigmatism or corneal scarring for example. In at least
some instances, the
irregularity of the eye may not be easily corrected with prior methods and
apparatus. Prior
approaches to treating the diseased cornea have included keratoplasty, such as
penetrating
keratoplasty (hereinafter "PK"), for example. The prior keratoplasty
procedures can result in
less than ideal patient outcomes in at least some instances. For example,
patients may have less
than ideal visual acuity after keratoplasty procedures. In at least some
instances, such less than
ideal visual acuity may be caused than less than ideal positioning and
location of tissue cuts.
[0004] Prior short pulse laser systems have been used to cut tissue, and
have been used to
treat many patients. However, the prior short pulse systems may provide less
than ideal results
in at least some instances. For example, the alignment of the eye with the
laser surgery system
can be less than ideal in at least some instances, such as when refractive
treatment of the cornea
of the eye is combined with a treatment of the lens of the eye such as removal
of the cortex and
nucleus from the eye. In another example, the laser eye surgery system may not
properly take
into account the different indices of refraction of the eye anatomy in at
least some instances,
which may affect the positioning of tissue cuts in at least some instances.
[0005] In order to more accurately treat the eye, prior methods and
apparatus have
combined optical measurement systems such as tomography systems. However, the
accuracy of
such prior measurement devices can be less than ideal in at least some
instances. For example,
to determine the physical location of a structure, the prior devices may rely
on an assumed index
of refraction which can vary from the actual index of refraction of the
particular eye of an
individual being treated. Further, at least some prior devices may rely on an
assumed average
value of the index of refraction for tissues that have a varying index of
refraction such as tissue
of the lens. The amount of variation of the index of refraction within an
individual may vary
more, or less, than normative values for a population, potentially making
assumed values less
accurate in at least some instances. In at least some instances, the treatment
beam may comprise
different wavelengths than the measurement beam, potentially further
compounding the errors in
the measurements in at least some instances.
[0006] The decreased accuracy of the prior methods an apparatus may
limit, in at least
some respects, the treatment of the prior methods and apparatus. For example,
variability of the
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index of refraction may result in variability of the depth at which tissue is
incised, thereby
potentially decreasing the accuracy of the prior surgical procedures and
potentially limiting the
use of lasers to incise tissue near sensitive.
[0007] In light of the above, it would be desirable to provide improved
methods and
apparatus that overcome at least some of the above limitations of the above
prior systems and
methods. Ideally, these improved systems and methods will provide in situ
measurement of the
index of refraction of optically transmissive materials, provide improved
measurement of the
location of structures within the optically transmissive materials, to provide
improved treatment
with more accurate focus of laser beams within the material and to provide
better and more
accurate surgical and treatment planning.
SUMMARY OF THE INVENTION
[0008] Hence, to obviate one or more problems due to limitations and
disadvantages of
the related art, this disclosure provides many embodiments where, an
ophthalmic measurement
and laser surgery system, comprises: a laser source configured to produce a
pulsed laser beam; a
corneal topography subsystem; an axis determining subsystem; a ranging
subsystem comprising
an Optical Coherence Tomographer (OCT); and a refractive index determining
subsystem. Each
of the laser source, the corneal topography subsystem, the axis determining
subsystem, and the
refractive index determining subsystem under the operative control of a
controller, wherein the
controller is configure to: operate the corneal topography subsystem to obtain
corneal surface
information; operate the axis determining subsystem to identify one or more
ophthalmic axes of
the eye; operate the OCT to sequentially scan the eye in a plurality of OCT
scan patterns, the
plurality of scan patterns configured to determine an axial length of the eye;
operate the
refractive index determining subsystem so to determine an index of refraction
of one or more
ophthalmic tissues. At least one of the corneal surface information,
ophthalmic axis information,
and axial length is modified based on the determined index of refraction.
[0009] In many embodiments, the present invention comprises methods for
improved
ophthalmic and biometric measurements comprising one or more steps carried out
by the laser
surgery system or controller of the laser surgical system. The methods of the
present invention
may include: obtaining corneal surface information; identifying one or more
ophthalmic axes of
the eye; scanning the eye in a plurality of OCT scan patterns, the plurality
of scan patterns
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configured to determine an axial length of the eye; and determine an index of
refraction of one or
more ophthalmic tissues. At least one of the corneal surface information,
ophthalmic axis
information, and axial length is modified based on the determined index of
refraction.
[0010] In many embodiments, the corneal surface information comprises one
or more
selected from the group consisting of anterior corneal surface information and
posterior corneal
surface information.
[0011] In many embodiments, the controller is further configured to
perform a plurality
of OCT scan patterns comprising a lenticular OCT scan segment scan pattern
suitable to measure
a plurality lens information selected from the group consisting of a lens
thickness, an anterior
lens surface, a posterior lens surface, and a lens equator. In many
embodiments, at least one of
the lens information, the corneal surface information, ophthalmic axis
information, and axial
length is modified based on the determined index of refraction, thereby
obtaining modified
structural information. The modified structural information has improved
accuracy over prior art
methods.
[0012] In many embodiments, the controller is configured to construct a
model of the
eye based on modified structural information and one or more of the lens
information, the
corneal surface information, and the ophthalmic axis. In many embodiments, the
model is
performed using ray tracing.
[0013] In many embodiments, the one or more ophthalmic axes are selected
from the
group consisting of an optical axis, a treatment axis a visual axis and a
fiducial marker axis.
[0014] In many embodiments, the controller is configured to sequentially
scan the eye in
a plurality of OCT scan patterns, each scan pattern being at a different axial
depth of a patient's
eye. The plurality of imaging scan patterns may comprise an anterior segment
OCT scan pattern
suitable to measure corneal surface information of a plurality of an anterior
corneal surface, a
posterior corneal surface, a corneal pachymetry, a central corneal thickness,
and anterior
chamber depth of a patient's eye. The selected corneal information so measured
may be
modified based in part on a determined index of refraction. The plurality of
imaging scan
patterns may comprise a lenticular OCT scan segment scan pattern suitable to
measure lens
information of a plurality of a lens thickness, an anterior lens surface, a
posterior lens surface,
and a lens equator. The lens information so measured may be modified based on
a determined
index of refraction. The plurality of imaging scan patterns comprise an
retinal OCT segment
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scan pattern suitable to measure at least one of an axial length and retinal
layer thickness
information. The selected ones of the axial length and the retinal layer may
be modified based
on a determined index of refraction.
[0015] In many embodiments, the ophthalmic tissue comprises an
optically transmissive
tissue structure of an eye of a subject. The optically transmissive tissue
structure of the eye
comprises one or more of a tear film, a cornea, an aqueous humor, a lens, an
anterior lens
capsule, a lens cortex, an anterior portion of the lens cortex, a posterior
portion of the lens cortex,
a lens nucleus, a posterior lens capsule, or a vitreous humor.
[0016] In many embodiments, the system comprises a processor; and a
memory operable
to store data acquired from each of the corneal topography subsystem, the axis
determining
subsystem, and the OCT, wherein the stored data includes a plurality of
corneal and lens surface
information, the axis information, and the axial length of the eye.
[0017] In many embodiments, the memory operable to store Intraocular
Lens ("IOU')
Data, the IOL data including a plurality of dioptic power, anterior and
posterior radius, IOL
thickness, refractive index and dispersion, asphericity, toricity, echelette
features, haptic
angulation and lens filter.
[0018] In many embodiments, the system is configured to select an
optimized IOL
characteristic or IOL model.
[0019] In some embodiments, for each of Intraocular Lens ("IOU') model
having
associated with it a plurality of predetermined parameters selected from the
group consisting of
dioptic power, refractive index and dispersion, anterior and posterior radius,
IOL thickness,
asphericity, toricity, echelette design, haptic angulation and lens filter,
the controller is
programmed to execute a program to:
(1) model the subject eye with the intraocular lens based in part on the
stored data;
(2) simulate the subject eye based on the plurality of IOL predetermined
parameters and
the predicted IOL position;
(3) perform a ray tracing and, optionally an IOL spherical equivalent (SE) and
cylinder
(C) power calculation, as well as determine the optimum IOL orientation based
on said eye model;
and
(4) identify one IOL power for one or more IOL models from the plurality of
IOLs
corresponding to the optimized IOL(s) based on predetermined criteria.
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[0020] In many embodiments, the modeling of the subject eye is
performed with the IOL
position with the equator of the IOL lens positioned at the same location of
the equator of the
lens of the subject eye. The modeling of the subject eye may also be performed
with the haptics
of the IOL located at the same location as the equator of the lens of the
subject eye
[0021] In some embodiments for each of Intraocular Lens ("IOU') model
having
associated with it a plurality of predetermined parameters selected from the
group consisting of
dioptic power, refractive index and dispersion, anterior and posterior radius,
IOL thickness,
asphericity, toricity, echelette design, haptic angulation and lens filter,
the controller is
programmed to execute a program to:
(1) modeling the subject eye with the intraocular lens based on the stored
data;
(2) simulating the subject eye based on the plurality of IOL predetermined
parameters
and the predicted IOL position;
(3) perform a ray tracing and, optionally, an IOL spherical equivalent (SE)
and cylinder
(C) power calculation, as well as determine the optimum IOL orientation based
on said eye model;
and
(4) identify one IOL model from the plurality of IOLs corresponding to the
optimized
IOL based on predetermined criteria.
[0022] In many embodiments, the system further comprises a scanning
system, wherein
the controller is configured to operate the scanning system to deflect the
laser beam to in one or
more treatment patterns, the treatment pattern configured so to incise in one
or more ocular
tissues in the eye of the patient.
[0023] In some embodiments, the one or more treatment patterns is a
capsulotomy
treatment pattern configured to incise a capsulotomy in the lens capsule.
[0024] In some embodiments, the one or more treatment patterns is a
lens fragmentation
treatment pattern configured to fragment the lens.
[0025] In some embodiments, the one or more treatment patterns is a
relaxing incision
treatment pattern.
[0026] In some embodiments, the one or more treatment patterns is a
cataract incision
treatment pattern.
[0027] In some embodiments, the one or more treatment patterns is a
sideport incision
treatment pattern.
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[0028] This summary and the following detailed description are merely
exemplary,
illustrative, and explanatory, and are not intended to limit, but to provide
further explanation of
the embodiments as claimed. Additional features and advantages of the
embodiments will be set
forth in the descriptions that follow, and in part will be apparent from the
description, or may be
learned by practice of the embodiments. The objectives and other advantages of
the
embodiments will be realized and attained by the structure particularly
pointed out in the written
description, claims and the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The novel features of the embodiments are set forth with
particularity in
the appended claims. A better understanding of the features and advantages
will be facilitated by
referring to the following detailed description that sets forth illustrative,
as well as to the
accompanying drawings, in which like numerals refer to like parts throughout
the different
views. Like parts, however, do not always have like reference numerals.
Further, the drawings
are not drawn to scale, and emphasis has instead been placed on illustrating
the principles of the
embodiments. All illustrations are intended to convey concepts, where relative
sizes, shapes, and
other detailed attributes may be illustrated schematically rather than
depicted literally or
precisely.
[0030] FIG. 1 shows a perspective view showing a laser eye surgery
system, in
accordance with many embodiments;
[0031] FIG. 2 shows a simplified block diagram showing a top level
view of the
configuration of a laser eye surgery system, in accordance with many
embodiments;
[0032] FIG. 3A shows a simplified block diagram illustrating the
configuration of
an optical assembly of a laser eye surgery system, in accordance with many
embodiments;
[0033] FIG. 3B shows a mapped treatment region of the eye
comprising the
cornea, the posterior capsule, and the limbus, in accordance with many
embodiments;
[0034] FIG. 4A shows correspondence among movable and sensor
components of
the laser delivery system, in accordance with many embodiments;
[0035] FIG. 4B shows mapping of coordinate references from an eye
space
coordinate reference system to a machine coordinate reference system, in
accordance with many
embodiments;
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[0036] FIG. 5A shows a flow chart of a method for mapping the eye,
in
accordance with many embodiments;
[0037] FIG. 5B shows a simplified block diagram showing a top level
view of the
configuration of a laser eye surgery system which can perform the method of
FIG. 5A, in
accordance with many embodiments;
[0038] FIG. 6A shows a coordinate system overlaid on an image of
the eye, in
accordance with many embodiments;
[0039] FIG. 6A1 shows corneal profile data for the coordinate
system and image
of FIG. 6A;
[0040] FIG. 6A2 shows corneal thickness profile data for the
coordinate system
and images of FIG. 6A and 6A1;
[0041] FIG. 6A3 shows corneal thickness profile maps for the
coordinate system
and images of FIG. 6A, 6A1 and 6A2;
[0042] FIG. 6B shows a distorted coordinate system overlaid on the
eye image of
FIG. 6A to account for distortions due coupling of the eye to a patient
interface, in accordance
with many embodiments; and
[0043] FIG. 6C shows a distorted coordinate system overlaid on the
eye image of
FIG. 6B to account for distortion due coupling of the eye to a patient
interface as well as liquid in
the patient interface disposed over the eye, in accordance with many
embodiments;
[0044] FIG. 6C1 shows corneal profile data for the coordinate
system and image
of FIG. 6C;
[0045] FIG. 6C2 shows corneal thickness profile data for the
coordinate system
and images of FIGS. 6C and 6C1;
[0046] FIG. 6C3 shows corneal thickness profile maps for the
coordinate system
and images of FIG. 6C, 6C1 and 6C2;
[0047] FIGS. 7A and 7B show side views of axes of the eye when the
eye views a
fixation target and the eye is measured prior to contacting a patient
interface, in accordance with
many embodiments;
[0048] FIG. 7C shows an anterior view of an eye as in FIGS. 7A and
7B, in
accordance with embodiments;
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[0049] FIGS. 7D and 7E show the eye as in Figures 7A to 7C coupled
to a patient
interface for treatment, in accordance with many embodiments;
[0050] FIG. 7F shows coordinate transformations of the measurement
coordinate
reference system prior to contacting the eye with the laser system and the
measurement
coordinate reference system when the eye contacts the patient interface as in
Figures 7D and 7E;
[0051] FIG. 7G shows an optical schematic of the eye as in Figures
7A and 7B;
[0052] FIG. 8A shows a topography measurement structure configured
to couple
to a patient interface to measure the eye prior to the eye contacting the
patient interface, in
accordance with embodiments;
[0053] FIG. 8B shows components of the patient interface and the
topography
measurement structure configured to couple to the patient interface, in
accordance with
embodiments;
[0054] FIG. 8C shows a perspective view of the interface end of the
topography
measurement structure;
[0055] FIG. 8D shows an end face of the topography measurement
structure
showing the circular opening and the aperture;
[0056] FIG. 9 shows scanning regions in the eye of an optical
coherence
tomography apparatus according to many aspects of the present invention;
[0057] FIG. 10A shows a light source focused onto the lens of the
eye to
determine an index of refraction of the eye;
[0058] FIGS. 10B and 10C show focal points through various
anatomical
structures for determining indices of refraction of the various anatomical
structures;
[0059] FIG. 10D shows a refractive index profile of a lens of an
eye according to
many embodiments;
[0060] FIG. 11-6 shows a flow chart depicting a method for
determining an index
of refraction of a target material according to many embodiments; and
[0061] FIG. 12-7 shows an intensity graph of various beam paths
through various
anatomical structures of the eye for various desired focal points.
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DETAILED DESCRIPTION OF THE INVENTION
[0062] Methods and systems related to ophthalmic measurements and laser
eye surgery
are disclosed. In many embodiments, a laser is used to form precise incisions
in the cornea, in
the lens capsule, and/or in the crystalline lens nucleus. Although specific
reference is made to
tissue resection for laser eye surgery, embodiments as described herein can be
used in one or
more of many ways with many surgical procedures and devices, such as
orthopedic surgery,
robotic surgery and microkeratomes.
[0063] The embodiments as described herein are particularly well suited
for mapping the
index of refraction with a first beam having first one or more wavelengths of
light. The mapped
index of refraction can be used to determine the physical location of the
tissue structure, in
response to a mapped index of refraction along the measurement beam path
extending to the
tissue structure, for example.
[0064] A laser may be used to form precise incisions in the cornea, in
the lens capsule,
and/or in the crystalline lens nucleus, for example. The embodiments as
described herein can be
particularly well suited for increasing the accuracy of the cutting of the
material such as tissue,
for example. For example, the mapped index of refraction can be used to
determine the location
of one or more components of the laser system such as a lens and movable
mirrors in order to
more accurately place the laser beam focus and tissue incisions. In many
embodiments, tissue
structures are mapped with a beam of a measurement system such as a tomography
system and
the index of refraction of the tissue is mapped with the focused measurement
beam as described
herein. The tissue structures mapped with the measurement beam can be adjusted
in response to
the mapped indices of refraction from the focused measurement beam in order to
more
accurately determine the physical locations of the tissue structures.
[0065] The physical locations and dimensions of the tissue structures of
the eye and the
mapped indices of refraction can be used to more accurately determine the
positions of the laser
system components. For example, the laser beam incision profile of the tissue
of the eye can be
determined in response to physical locations of tissue structures or the
locations of the structures
from tomography images, and combinations thereof. In many embodiments, the
mapped indices
of refraction determined with the focused measurement beam having first one or
more
wavelengths are adjusted in response to an index of refraction of the laser
treatment beam having
second one or more wavelengths in order to provide mapping of the index of
refraction for the
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treatment beam. The range of the first one or more wavelengths can overlap
with the range of
the second one or more wavelengths such that the wavelengths are similar, or
have non-
overlapping ranges such that the first one or more wavelengths differs from
the second one or
more wavelengths. The mapped index of refraction of the treatment beam can be
combined with
one or more of the physical locations and dimensions of the tissue structures,
the targeted
incision profile, or the mapped index of refraction of the focused measurement
beam, in order to
determine the positions of the mirrors and lenses of the laser treatment
system to place the laser
beam incisions at the targeted locations of the eye.
[0066] In many embodiments, the index of refraction of the treatment beam
can be
determined by adjusting the measured index of refraction of the measurement
beam to correct for
differences in the indices of refraction of the treatment beam and measurement
beam.
Alternatively or in combination a baseline index of refraction of the
treatment beam can be
adjusted in response to the index of refraction measured with the measurement
beam. In many
embodiments, a baseline index of refraction is adjusted in response to the
measured index of
refraction. The baseline index of refraction may comprise an index of
refraction of a structure of
the eye. While the index of refraction of tissue such as eye can vary with
wavelength as
described herein, approximate baseline values include: aqueous humor 1.33;
cornea 1.38;
vitreous humor 1.34; and lens 1.36 to 1.41, in which the index of the lens can
differ for the
capsule, the cortex and the nucleus, for example. The baseline phase indices
of refraction of
water and saline can be about 1.325 for the ultrafast laser at 1030 nm and
about 1.328 for the
OCT system at 830 nm, and this proportional difference can be used to
determine the index of
refraction of the treatment beam in response to the index of refraction
measured with the
measurement beam, for example. The group refractive index of 1.339 differs on
the order of 1%
for the OCT beam wavelength and spectral bandwidth. Many embodiments herein
provide
methods and apparatus for determining the indices of refraction, the phase
indices of refraction,
and group indices of refraction of the tissues of the eye for the wavelengths
of the measurement
and treatment systems as described herein.
[0067] The embodiments disclosed herein are well suited for combination
with prior
laser surgery systems, such as the CATALYS Precision Laser System available
from Abbott
Medical Optics Inc., and similar systems. Such systems can be modified in
accordance with the
teachings disclosed herein and to more accurately measure and treat the eye.
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[0068] As used herein like characters such as reference numerals and
letters described
like elements.
[0069] As used herein, the terms anterior and posterior refers to known
orientations with
respect to the patient. Depending on the orientation of the patient for
surgery, the terms anterior
and posterior may be similar to the terms upper and lower, respectively, such
as when the patient
is placed in a supine position on a bed. The terms distal and anterior may
refer to an orientation
of a structure from the perspective of the user, such that the terms proximal
and distal may be
similar to the terms anterior and posterior when referring to a structure
placed on the eye, for
example. A person of ordinary skill in the art will recognize many variations
of the orientation
of the methods and apparatus as described herein, and the terms anterior,
posterior, proximal,
distal, upper, and lower are used merely by way of example.
[0070] As used herein, the terms first and second are used to describe
structures and
methods without limitation as to the order of the structures and methods which
can be in any
order, as will be apparent to a person of ordinary skill in the art based on
the teachings provided
herein.
[0071] The processor system may comprise tangible medium embodying
instructions of a
computer program to perform one or more of the method steps as described
herein.
[0072] FIG. 1 shows a laser eye surgery system 2, in accordance with many
embodiments, operable to form precise incisions in the cornea, in the lens
capsule, and/or in the
crystalline lens nucleus. The system 2 includes a main unit 4, a patient chair
6, a dual function
footswitch 8, and a laser footswitch 10.
[0073] The main unit 4 includes many primary subsystems of the system 2.
For example,
externally visible subsystems include a touch-screen control panel 12, a
patient interface
assembly 14, patient interface vacuum connections 16, a docking control keypad
18, a patient
interface radio frequency identification (RFID) reader 20, external
connections 22 (e.g., network,
video output, footswitch, USB port, door interlock, and AC power), laser
emission indicator 24,
emergency laser stop button 26, key switch 28, and USB data ports 30.
[0074] The patient chair 6 includes a base 32, a patient support bed 34,
a headrest 36, a
positioning mechanism, and a patient chair joystick control 38 disposed on the
headrest 36. The
positioning control mechanism is coupled between the base 32 and the patient
support bed 34
and headrest 36. The patient chair 6 is configured to be adjusted and oriented
in three axes (x, y,
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and z) using the patient chair joystick control 38. The headrest 36 and a
restrain system (not
shown, e.g., a restraint strap engaging the patient's forehead) stabilize the
patient's head during
the procedure. The headrest 36 includes an adjustable neck support to provide
patient comfort
and to reduce patient head movement. The headrest 36 is configured to be
vertically adjustable
to enable adjustment of the patient head position to provide patient comfort
and to accommodate
variation in patient head size.
[0075] The patient chair 6 allows for tilt articulation of the patient's
legs, torso, and head
using manual adjustments. The patient chair 6 accommodates a patient load
position, a suction
ring capture position, and a patient treat position. In the patient load
position, the chair 6 is
rotated out from under the main unit 4 with the patient chair back in an
upright position and
patient footrest in a lowered position. In the suction ring capture position,
the chair is rotated out
from under the main unit 4 with the patient chair back in reclined position
and patient footrest in
raised position. In the patient treat position, the chair is rotated under the
main unit 4 with the
patient chair back in reclined position and patient footrest in raised
position.
[0076] The patient chair 6 is equipped with a "chair enable" feature to
protect against
unintended chair motion. The patient chair joystick 38 can be enabled in
either of two ways.
First, the patient chair joystick 38 incorporates a "chair enable" button
located on the top of the
joystick. Control of the position of the patient chair 6 via the joystick 38
can be enabled by
continuously pressing the "chair enable" button. Alternately, the left foot
switch 40 of the dual
function footswitch 8 can be continuously depressed to enable positional
control of the patient
chair 6 via the joystick 38.
[0077] In many embodiments, the patient control joystick 38 is a
proportional controller.
For example, moving the joystick a small amount can be used to cause the chair
to move slowly.
Moving the joystick a large amount can be used to cause the chair to move
faster. Holding the
joystick at its maximum travel limit can be used to cause the chair to move at
the maximum chair
speed. The available chair speed can be reduced as the patient approaches the
patient interface
assembly 14.
[0078] The emergency stop button 26 can be pushed to stop emission of all
laser output,
release vacuum that couples the patient to the system 2, and disable the
patient chair 6. The stop
button 26 is located on the system front panel, next to the key switch 28.
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[0079] The key switch 28 can be used to enable the system 2. When in a
standby
position, the key can be removed and the system is disabled. When in a ready
position, the key
enables power to the system 2.
[0080] The dual function footswitch 8 is a dual footswitch assembly that
includes the left
foot switch 40 and a right foot switch 42. The left foot switch 40 is the
"chair enable"
footswitch. The right footswitch 42 is a "vacuum ON" footswitch that enables
vacuum to secure
a liquid optics interface suction ring to the patient's eye. The laser
footswitch 10 is a shrouded
footswitch that activates the treatment laser when depressed while the system
is enabled.
[0081] In many embodiments, the system 2 includes external communication
connections. For example, the system 2 can include a network connection (e.g.,
an RJ45
network connection) for connecting the system 2 to a network. The network
connection can be
used to enable network printing of treatment reports, remote access to view
system performance
logs, and remote access to perform system diagnostics. The system 2 can
include a video output
port (e.g., HDMI) that can be used to output video of treatments performed by
the system 2. The
output video can be displayed on an external monitor for, for example, viewing
by family
members and/or training. The output video can also be recorded for, for
example, archival
purposes. The system 2 can include one or more data output ports (e.g., USB)
for example, to
enable export of treatment reports to a data storage device. The treatments
reports stored on the
data storage device can then be accessed at a later time for any suitable
purpose such as, for
example, printing from an external computer in the case where the user without
access to
network based printing.
[0082] FIG. 2 shows a simplified block diagram of the system 2 coupled
with a patient
eye 43. The patient eye 43 comprises a cornea 43C, a lens 43L and an iris 431.
The iris 431
defines a pupil of the eye 43 that may be used for alignment of eye 43 with
system 2. The
system 2 includes a cutting laser subsystem 44, a ranging subsystem 46, an
alignment guidance
system 48, shared optics 50, a patient interface 52, control electronics 54, a
control panel/GUI
56, user interface devices 58, and communication paths 60. The control
electronics 54 is
operatively coupled via the communication paths 60 with the cutting laser
subsystem 44, the
ranging subsystem 46, the alignment guidance subsystem 48, the shared optics
50, the patient
interface 52, the control panel/GUI 56, and the user interface devices 58.
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[0083] In many embodiments, the cutting laser subsystem 44 incorporates
femtosecond
(FS) laser technology. By using femtosecond laser technology, a short duration
(e.g.,
approximately 10-13 seconds in duration) laser pulse (with energy level in the
micro joule
range) can be delivered to a tightly focused point to disrupt tissue, thereby
substantially lowering
the energy level required as compared to the level required for ultrasound
fragmentation of the
lens nucleus and as compared to laser pulses having longer durations.
[0084] The cutting laser subsystem 44 can produce laser pulses having a
wavelength
suitable to the configuration of the system 2. As a non-limiting example, the
system 2 can be
configured to use a cutting laser subsystem 44 that produces laser pulses
having a wavelength
from 1020 nm to 1050 nm. For example, the cutting laser subsystem 44 can have
a diode-
pumped solid-state configuration with a 1030 (+/-5) nm center wavelength.
[0085] The cutting laser subsystem 44 can include control and
conditioning components.
For example, such control components can include components such as a beam
attenuator to
control the energy of the laser pulse and the average power of the pulse
train, a fixed aperture to
control the cross-sectional spatial extent of the beam containing the laser
pulses, one or more
power monitors to monitor the flux and repetition rate of the beam train and
therefore the energy
of the laser pulses, and a shutter to allow/block transmission of the laser
pulses. Such
conditioning components can include an adjustable zoom assembly to adapt the
beam containing
the laser pulses to the characteristics of the system 2 and a fixed optical
relay to transfer the laser
pulses over a distance while accommodating laser pulse beam positional and/or
directional
variability, thereby providing increased tolerance for component variation.
[0086] The ranging subsystem 46 is configured to measure the spatial
disposition of eye
structures in three dimensions. The measured eye structures can include the
anterior and
posterior surfaces of the cornea, the anterior and posterior portions of the
lens capsule, the iris,
and the limbus. In many embodiments, the ranging subsystem 46 utilizes optical
coherence
tomography (OCT) imaging. As a non-limiting example, the system 2 can be
configured to use
an OCT imaging system employing wavelengths from 780 nm to 970 nm. For
example, the
ranging subsystem 46 can include an OCT imaging system that employs a broad
spectrum of
wavelengths from 810 nm to 850 nm. Such an OCT imaging system can employ a
reference
path length that is adjustable to adjust the effective depth in the eye of the
OCT measurement,
thereby allowing the measurement of system components including features of
the patient
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interface that lie anterior to the cornea of the eye and structures of the eye
that range in depth
from the anterior surface of the cornea to the posterior portion of the lens
capsule and beyond.
[0087] The alignment guidance subsystem 48 can include a laser diode or
gas laser that
produces a laser beam used to align optical components of the system 2. The
alignment
guidance subsystem 48 can include LEDs or lasers that produce a fixation light
to assist in
aligning and stabilizing the patient's eye during docking and treatment. The
alignment guidance
subsystem 48 can include a laser or LED light source and a detector to monitor
the alignment
and stability of the actuators used to position the beam in X, Y, and Z. The
alignment guidance
subsystem 48 can include a video system that can be used to provide imaging of
the patient's eye
to facilitate docking of the patient's eye 43 to the patient interface 52. The
imaging system
provided by the video system can also be used to direct via the GUI the
location of cuts. The
imaging provided by the video system can additionally be used during the laser
eye surgery
procedure to monitor the progress of the procedure, to track movements of the
patient's eye 43
during the procedure, and to measure the location and size of structures of
the eye such as the
pupil and/or limbus.
[0088] The shared optics 50 provides a common propagation path that is
disposed
between the patient interface 52 and each of the cutting laser subsystem 44,
the ranging
subsystem 46, and the alignment guidance subsystem 48. In many embodiments,
the shared
optics 50 includes beam combiners to receive the emission from the respective
subsystem (e.g.,
the cutting laser subsystem 44, and the alignment guidance subsystem 48) and
redirect the
emission along the common propagation path to the patient interface. In many
embodiments, the
shared optics 50 includes an objective lens assembly that focuses each laser
pulse into a focal
point. In many embodiments, the shared optics 50 includes scanning mechanisms
operable to
scan the respective emission in three dimensions. For example, the shared
optics can include an
XY-scan mechanism(s) and a Z-scan mechanism. The XY-scan mechanism(s) can be
used to
scan the respective emission in two dimensions transverse to the propagation
direction of the
respective emission. The Z-scan mechanism can be used to vary the depth of the
focal point
within the eye 43. In many embodiments, the scanning mechanisms are disposed
between the
laser diode and the objective lens such that the scanning mechanisms are used
to scan the
alignment laser beam produced by the laser diode. In contrast, in many
embodiments, the video
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system is disposed between the scanning mechanisms and the objective lens such
that the
scanning mechanisms do not affect the image obtained by the video system.
[0089] The patient interface 52 is used to restrain the position of the
patient's eye 43
relative to the system 2. In many embodiments, the patient interface 52
employs a suction ring
that is vacuum attached to the patient's eye 43. The suction ring is then
coupled with the patient
interface 52, for example, using vacuum to secure the suction ring to the
patient interface 52. In
many embodiments, the patient interface 52 includes an optically transmissive
structure having a
posterior surface that is displaced vertically from the anterior surface of
the patient's cornea and a
region of a suitable liquid (e.g., a sterile buffered saline solution (BSS)
such as Alcon BSS
(Alcon Part Number 351-55005-1) or equivalent) is disposed between and in
contact with the
patient interface lens posterior surface and the patient's cornea and forms
part of a transmission
path between the shared optics 50 and the patient's eye 43. The optically
transmissive structure
may comprise a lens 96 having one or more curved surfaces. Alternatively, the
patient interface
52 may comprise an optically transmissive structure having one or more
substantially flat
surfaces such as a parallel plate or wedge. In many embodiments, the patient
interface lens is
disposable and can be replaced at any suitable interval, such as before each
eye treatment.
[0090] The control electronics 54 controls the operation of and can
receive input from the
cutting laser subsystem 44, the ranging subsystem 46, the alignment guidance
subsystem 48, the
patient interface 52, the control panel/GUI 56, and the user interface devices
58 via the
communication paths 60. The communication paths 60 can be implemented in any
suitable
configuration, including any suitable shared or dedicated communication paths
between the
control electronics 54 and the respective system components. The control
electronics 54 can
include any suitable components, such as one or more processor, one or more
field-
programmable gate array (FPGA), and one or more memory storage devices. In
many
embodiments, the control electronics 54 controls the control panel/GUI 56 to
provide for pre-
procedure planning according to user specified treatment parameters as well as
to provide user
control over the laser eye surgery procedure.
[0091] The user interface devices 58 can include any suitable user input
device suitable
to provide user input to the control electronics 54. For example, the user
interface devices 58
can include devices such as, for example, the dual function footswitch 8, the
laser footswitch 10,
the docking control keypad 18, the patient interface radio frequency
identification (RFID) reader
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20, the emergency laser stop button 26, the key switch 28, and the patient
chair joystick control
38.
[0092] FIG. 3A is a simplified block diagram illustrating an assembly 62,
in accordance
with many embodiments, that can be included in the system 2. The assembly 62
is a non-
limiting example of suitable configurations and integration of the cutting
laser subsystem 44, the
ranging subsystem 46, the alignment guidance subsystem 48, the shared optics
50, and the
patient interface 52. Other configurations and integration of the cutting
laser subsystem 44, the
ranging subsystem 46, the alignment guidance subsystem 48, the shared optics
50, and the
patient interface 52 may be possible and may be apparent to a person of skill
in the art.
[0093] The assembly 62 is operable to project and scan optical beams into
the patient's
eye 43. The cutting laser subsystem 44 includes an ultrafast (UF) laser 64
(e.g., a femtosecond
laser). Using the assembly 62, optical beams can be scanned in the patient's
eye 43 in three
dimensions: X, Y, and Z. For example, short-pulsed laser light generated by
the UF laser 64 can
be focused into eye tissue to produce dielectric breakdown to cause
photodisruption around the
focal point (the focal zone), thereby rupturing the tissue in the vicinity of
the photo-induced
plasma. In the assembly 62, the wavelength of the laser light can vary between
800 nm to 1200
nm and the pulse width of the laser light can vary from 10 fs to 10000 fs. The
pulse repetition
frequency can also vary from 10 kHz to 500 kHz. Safety limits with regard to
unintended
damage to non-targeted tissue bound the upper limit with regard to repetition
rate and pulse
energy. Threshold energy, time to complete the procedure, and stability can
bound the lower
limit for pulse energy and repetition rate. The peak power of the focused spot
in the eye 43 and
specifically within the crystalline lens and the lens capsule of the eye is
sufficient to produce
optical breakdown and initiate a plasma-mediated ablation process. Near-
infrared wavelengths
for the laser light are preferred because linear optical absorption and
scattering in biological
tissue is reduced for near-infrared wavelengths. As an example, the laser 64
can be a repetitively
pulsed 1031 nm device that produces pulses with less than 600 fs duration at a
repetition rate of
120 kHz (+/-5%) and individual pulse energy in the 1 to 20 micro joule range.
[0094] The cutting laser subsystem 44 is controlled by the control
electronics 54 and the
user, via the control panel/GUI 56 and the user interface devices 58, to
create a laser pulse beam
66. The control panel/GUI 56 is used to set system operating parameters,
process user input,
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display gathered information such as images of ocular structures, and display
representations of
incisions to be formed in the patient's eye 43.
[0095] The generated laser pulse beam 66 proceeds through a zoom assembly
68. The
laser pulse beam 66 may vary from unit to unit, particularly when the UF laser
64 may be
obtained from different laser manufacturers. For example, the beam diameter of
the laser pulse
beam 66 may vary from unit to unit (e.g., by +/-20%). The beam may also vary
with regard to
beam quality, beam divergence, beam spatial circularity, and astigmatism. In
many
embodiments, the zoom assembly 68 is adjustable such that the laser pulse beam
66 exiting the
zoom assembly 68 has consistent beam diameter and divergence unit to unit.
[0096] After exiting the zoom assembly 68, the laser pulse beam 66
proceeds through an
attenuator 70. The attenuator 70 is used to adjust the transmission of the
laser beam and thereby
the energy level of the laser pulses in the laser pulse beam 66. The
attenuator 70 is controlled via
the control electronics 54.
[0097] After exiting the attenuator 70, the laser pulse beam 66 proceeds
through an
aperture 72. The aperture 72 sets the outer useful diameter of the laser pulse
beam 66. In turn
the zoom determines the size of the beam at the aperture location and
therefore the amount of
light that is transmitted. The amount of transmitted light is bounded both
high and low. The
upper is bounded by the requirement to achieve the highest numerical aperture
achievable in the
eye. High NA promotes low threshold energies and greater safety margin for
untargeted tissue.
The lower is bound by the requirement for high optical throughput. Too much
transmission loss
in the system shortens the lifetime of the system as the laser output and
system degrades over
time. Additionally, consistency in the transmission through this aperture
promotes stability in
determining optimum settings (and sharing of) for each procedure. Typically to
achieve optimal
performance the transmission through this aperture as set to 88% to 92%.
[0098] After exiting the aperture 72, the laser pulse beam 66 proceeds
through two output
pickoffs 74. Each output pickoff 74 can include a partially reflecting mirror
to divert a portion of
each laser pulse to a respective output monitor 76. Two output pickoffs 74
(e.g., a primary and a
secondary) and respective primary and secondary output monitors 76 are used to
provide
redundancy in case of malfunction of the primary output monitor 76.
[0099] After exiting the output pickoffs 74, the laser pulse beam 66
proceeds through a
system-controlled shutter 78. The system-controlled shutter 78 ensures on/off
control of the
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laser pulse beam 66 for procedural and safety reasons. The two output pickoffs
precede the
shutter allowing for monitoring of the beam power, energy, and repetition rate
as a pre-requisite
for opening the shutter.
[0100] After exiting the system-controlled shutter 78, the optical beam
proceeds through
an optics relay telescope 80. The optics relay telescope 80 propagates the
laser pulse beam 66
over a distance while accommodating positional and/or directional variability
of the laser pulse
beam 66, thereby providing increased tolerance for component variation. As an
example, the
optical relay can be a keplerian afocal telescope that relays an image of the
aperture position to a
conjugate position near to the xy galvo mirror positions. In this way, the
position of the beam at
the XY galvo location is invariant to changes in the beams angle at the
aperture position.
Similarly the shutter does not have to precede the relay and may follow after
or be included
within the relay.
[0101] After exiting the optics relay telescope 80, the laser pulse beam
66 is transmitted
to the shared optics 50, which propagates the laser pulse beam 66 to the
patient interface 52. The
laser pulse beam 66 is incident upon a beam combiner 82, which reflects the
laser pulse beam 66
while transmitting optical beams from the ranging subsystem 46 and the
alignment guidance
subsystem: AIM 48.
[0102] Following the beam combiner 82, the laser pulse beam 66 continues
through a Z-
telescope 84, which is operable to scan focus position of the laser pulse beam
66 in the patient's
eye 43 along the Z axis. For example, the Z-telescope 84 can include a
Galilean telescope with
two lens groups (each lens group includes one or more lenses). One of the lens
groups moves
along the Z axis about the collimation position of the Z-telescope 84. In this
way, the focus
position of the spot in the patient's eye 43 moves along the Z axis. In
general, there is a
relationship between the motion of lens group and the motion of the focus
point. For example,
the Z-telescope can have an approximate 2x beam expansion ratio and close to a
1:1 relationship
of the movement of the lens group to the movement of the focus point. The
exact relationship
between the motion of the lens and the motion of the focus in the z axis of
the eye coordinate
system does not have to be a fixed linear relationship. The motion can be
nonlinear and directed
via a model or a calibration from measurement or a combination of both.
Alternatively, the other
lens group can be moved along the Z axis to adjust the position of the focus
point along the Z
axis. The Z-telescope 84 functions as z-scan device for scanning the focus
point of the laser-
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pulse beam 66 in the patient's eye 43. The Z-telescope 84 can be controlled
automatically and
dynamically by the control electronics 54 and selected to be independent or to
interplay with the
X and Y scan devices described next.
[0103] After passing through the Z-telescope 84, the laser pulse beam 66
is incident upon
an X-scan device 86, which is operable to scan the laser pulse beam 66 in the
X direction, which
is dominantly transverse to the Z axis and transverse to the direction of
propagation of the laser
pulse beam 66. The X-scan device 86 is controlled by the control electronics
54, and can include
suitable components, such as a motor, galvanometer, or any other well-known
optic moving
device. The relationship of the motion of the beam as a function of the motion
of the X actuator
does not have to be fixed or linear. Modeling or calibrated measurement of the
relationship or a
combination of both can be determined and used to direct the location of the
beam.
[0104] After being directed by the X-scan device 86, the laser pulse beam
66 is incident
upon a Y-scan device 88, which is operable to scan the laser pulse beam 66 in
the Y direction,
which is dominantly transverse to the X and Z axes. The Y-scan device 88 is
controlled by the
control electronics 54, and can include suitable components, such as a motor,
galvanometer, or
any other well-known optic moving device. The relationship of the motion of
the beam as a
function of the motion of the Y actuator does not have to be fixed or linear.
Modeling or
calibrated measurement of the relationship or a combination of both can be
determined and used
to direct the location of the beam. Alternatively, the functionality of the X-
Scan device 86 and
the Y-Scan device 88 can be provided by an XY-scan device configured to scan
the laser pulse
beam 66 in two dimensions transverse to the Z axis and the propagation
direction of the laser
pulse beam 66. The X-scan and Y-scan devices 86, 88 change the resulting
direction of the laser
pulse beam 66, causing lateral displacements of UF focus point located in the
patient's eye 43.
[0105] After being directed by the Y-scan device 88, the laser pulse beam
66 passes
through a beam combiner 90. The beam combiner 90 is configured to transmit the
laser pulse
beam 66 while reflecting optical beams to and from a video subsystem 92 of the
alignment
guidance subsystem 48.
[0106] After passing through the beam combiner 90, the laser pulse beam
66 passes
through an objective lens assembly 94. The objective lens assembly 94 can
include one or more
lenses. In many embodiments, the objective lens assembly 94 includes multiple
lenses. The
complexity of the objective lens assembly 94 may be driven by the scan field
size, the focused
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spot size, the degree of telecentricity, the available working distance on
both the proximal and
distal sides of objective lens assembly 94, as well as the amount of
aberration control.
[0107] After passing through the objective lens assembly 94, the laser
pulse beam 66
passes through the patient interface 52. As described above, in many
embodiments, the patient
interface 52 includes a patient interface lens 96 having a posterior surface
that is displaced
vertically from the anterior surface of the patient's cornea and a region of a
suitable liquid (e.g., a
sterile buffered saline solution (BSS) such as Alcon BSS (Alcon Part Number
351-55005-1) or
equivalent) is disposed between and in contact with the posterior surface of
the patient interface
lens 96 and the patient's cornea and forms part of an optical transmission
path between the
shared optics 50 and the patient's eye 43.
[0108] The shared optics 50 under the control of the control electronics
54 can
automatically generate aiming, ranging, and treatment scan patterns. Such
patterns can be
comprised of a single spot of light, multiple spots of light, a continuous
pattern of light, multiple
continuous patterns of light, and/or any combination of these. In addition,
the aiming pattern
(using the aim beam 108 described below) need not be identical to the
treatment pattern (using
the laser pulse beam 66), but can optionally be used to designate the
boundaries of the treatment
pattern to provide verification that the laser pulse beam 66 will be delivered
only within the
desired target area for patient safety. This can be done, for example, by
having the aiming
pattern provide an outline of the intended treatment pattern. This way the
spatial extent of the
treatment pattern can be made known to the user, if not the exact locations of
the individual spots
themselves, and the scanning thus optimized for speed, efficiency, and/or
accuracy. The aiming
pattern can also be made to be perceived as blinking in order to further
enhance its visibility to
the user. Likewise, the ranging beam 102 need not be identical to the
treatment beam or pattern.
The ranging beam needs only to be sufficient enough to identify targeted
surfaces. These
surfaces can include the cornea and the anterior and posterior surfaces of the
lens and may be
considered spheres with a single radius of curvature. Also the optics shared
by the alignment
guidance: video subsystem does not have to be identical to those shared by the
treatment beam.
The positioning and character of the laser pulse beam 66 and/or the scan
pattern the laser pulse
beam 66 forms on the eye 43 may be further controlled by use of an input
device such as a
joystick, or any other appropriate user input device (e.g., control panel/GUI
56) to position the
patient and/or the optical system.
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[0109] The control electronics 54 can be configured to target the
targeted structures in
the eye 43 and ensure that the laser pulse beam 66 will be focused where
appropriate and not
unintentionally damage non-targeted tissue. Imaging modalities and techniques
described
herein, such as those mentioned above, or ultrasound may be used to determine
the location and
measure the thickness of the lens and lens capsule to provide greater
precision to the laser
focusing methods, including 2D and 3D patterning. Laser focusing may also be
accomplished by
using one or more methods including direct observation of an aiming beam, or
other known
ophthalmic or medical imaging modalities, such as those mentioned above,
and/or combinations
thereof. Additionally the ranging subsystem such as an OCT can be used to
detect features or
aspects involved with the patient interface. Features can include fiducials
places on the docking
structures and optical structures of the disposable lens such as the location
of the anterior and
posterior surfaces.
[0110] In the embodiment of FIG. 3, the ranging subsystem 46 includes an
OCT imaging
device. Additionally or alternatively, imaging modalities other than OCT
imaging can be used.
An OCT scan of the eye can be used to measure the spatial disposition (e.g.,
three dimensional
coordinates such as X, Y, and Z of points on boundaries) of structures of
interest in the patient's
eye 43. Such structures of interest can include, for example, the anterior
surface of the cornea,
the posterior surface of the cornea, the anterior portion of the lens capsule,
the posterior portion
of the lens capsule, the anterior surface of the crystalline lens, the
posterior surface of the
crystalline lens, the iris, the pupil, and/or the limbus. The spatial
disposition of the structures of
interest and/or of suitable matching geometric modeling such as surfaces and
curves can be
generated and/or used by the control electronics 54 to program and control the
subsequent laser-
assisted surgical procedure. The spatial disposition of the structures of
interest and/or of suitable
matching geometric modeling can also be used to determine a wide variety of
parameters related
to the procedure such as, for example, the upper and lower axial limits of the
focal planes used
for cutting the lens capsule and segmentation of the lens cortex and nucleus,
and the thickness of
the lens capsule among others.
[0111] The ranging subsystem 46 in FIG. 3 includes an OCT light source
and detection
device 98. The OCT light source and detection device 98 includes a light
source that generates
and emits light with a suitable broad spectrum. For example, in many
embodiments, the OCT
light source and detection device 98 generates and emits light with a broad
spectrum from 810
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nm to 850 nm wavelength. The generated and emitted light is coupled to the
device 98 by a
single mode fiber optic connection.
[0112] The light emitted from the OCT light source and detection device
98 is passed
through a beam combiner 100, which divides the light into a sample portion 102
and a reference
portion 104. A significant portion of the sample portion 102 is transmitted
through the shared
optics 50. A relative small portion of the sample portion is reflected from
the patient interface 52
and/or the patient's eye 43 and travels back through the shared optics 50,
back through the beam
combiner 100 and into the OCT light source and detection device 98. The
reference portion 104
is transmitted along a reference path 106 having an adjustable path length.
The reference path
106 is configured to receive the reference portion 104 from the beam combiner
100, propagate
the reference portion 104 over an adjustable path length, and then return the
reference portion
106 back to the beam combiner 100, which then directs the returned reference
portion 104 back
to the OCT light source and detection device 98. The OCT light source and
detection device 98
then directs the returning small portion of the sample portion 102 and the
returning reference
portion 104 into a detection assembly, which employs a time domain detection
technique, a
frequency detection technique, or a single point detection technique. For
example, a frequency-
domain technique can be used with an OCT wavelength of 830 nm and bandwidth of
10 nm.
[0113] Once combined with the UF laser pulse beam 66 subsequent to the
beam
combiner 82, the OCT sample portion beam 102 follows a shared path with the UF
laser pulse
beam 66 through the shared optics 50 and the patient interface 52. In this
way, the OCT sample
portion beam 102 is generally indicative of the location of the UF laser pulse
beam 66. Similar
to the UF laser beam, the OCT sample portion beam 102 passes through the Z-
telescope 84, is
redirected by the X-scan device 86 and by the Y-scan device 88, passes through
the objective
lens assembly 94 and the patient interface 52, and on into the eye 43.
Reflections and scatter off
of structures within the eye provide return beams that retrace back through
the patient interface
52, back through the shared optics 50, back through the beam combiner 100, and
back into the
OCT light source and detection device 98. The returning back reflections of
the sample portion
102 are combined with the returning reference portion 104 and directed into
the detector portion
of the OCT light source and detection device 98, which generates OCT signals
in response to the
combined returning beams. The generated OCT signals that are in turn
interpreted by the control
electronics to determine the spatial disposition of the structures of interest
in the patient's eye 43.
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The generated OCT signals can also be interpreted by the control electronics
to measure the
position and orientation of the patient interface 52, as well as to determine
whether there is liquid
disposed between the posterior surface of the patient interface lens 96 and
the patient's eye 43.
[0114] The OCT light source and detection device 98 works on the
principle of
measuring differences in optical path length between the reference path 106
and the sample path.
Therefore, different settings of the Z-telescope 84 to change the focus of the
UF laser beam do
not impact the length of the sample path for a axially stationary surface in
the eye of patient
interface volume because the optical path length does not change as a function
of different
settings of the Z-telescope 84. The ranging subsystem 46 has an inherent Z
range that is related
to light source and the detection scheme, and in the case of frequency domain
detection the Z
range is specifically related to the spectrometer, the wavelength, the
bandwidth, and the length of
the reference path 106. In the case of ranging subsystem 46 used in FIG. 3,
the Z range is
approximately 4-5 mm in an aqueous environment. Extending this range to at
least 20-25 mm
involves the adjustment of the path length of the reference path 106 via a
stage ZED within
ranging subsystem 46. Passing the OCT sample portion beam 102 through the Z-
telescope 84,
while not impacting the sample path length, allows for optimization of the OCT
signal strength.
This is accomplished by focusing the OCT sample portion beam 102 onto the
targeted structure.
The focused beam both increases the return reflected or scattered signal that
can be transmitted
through the single mode fiber, and increases the spatial resolution due to the
reduced extent of
the focused beam. The changing of the focus of the sample OCT beam can be
accomplished
independently of changing the path length of the reference path 106.
[0115] Because of the fundamental differences in how the sample portion
102 (e.g., 810
nm to 850 nm wavelengths) and the UF laser pulse beam 66 (e.g., 1020 nm to
1050 nm
wavelengths) propagate through the shared optics 50 and the patient interface
52 due to
influences such as immersion index, refraction, and aberration, both chromatic
and
monochromatic, care must be taken in analyzing the OCT signal with respect to
the UF laser
pulse beam 66 focal location. A calibration or registration procedure as a
function of X, Y, and
Z can be conducted in order to match the OCT signal information to the UF
laser pulse beam
focus location and also to the relative to absolute dimensional quantities.
[0116] There are many suitable possibilities for the configuration of the
OCT
interferometer. For example, alternative suitable configurations include time
and frequency
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domain approaches, single and dual beam methods, swept source, etc., are
described in U.S. Pat.
Nos. 5,748,898; 5,748,352; 5,459,570; 6,111,645; and 6,053,613.
[0117] The system 2 can be set to locate the anterior and posterior
surfaces of the lens
capsule and cornea and ensure that the UF laser pulse beam 66 will be focused
on the lens
capsule and cornea at all points of the desired opening. Imaging modalities
and techniques
described herein, such as for example, Optical Coherence Tomography (OCT), and
such as
Purkinje imaging, Scheimpflug imaging, confocal or nonlinear optical
microscopy, fluorescence
imaging, ultrasound, structured light, stereo imaging, or other known
ophthalmic or medical
imaging modalities and/or combinations thereof may be used to determine the
shape, geometry,
perimeter, boundaries, and/or 3-dimensional location of the lens and lens
capsule and cornea to
provide greater precision to the laser focusing methods, including 2D and 3D
patterning. Laser
focusing may also be accomplished using one or more methods including direct
observation of
an aiming beam, or other known ophthalmic or medical imaging modalities and
combinations
thereof, such as but not limited to those defined above.
[0118] Optical imaging of the cornea, anterior chamber and lens can be
performed using
the same laser and/or the same scanner used to produce the patterns for
cutting. Optical imaging
can be used to provide information about the axial location and shape (and
even thickness) of the
anterior and posterior lens capsule, the boundaries of the cataract nucleus,
as well as the depth of
the anterior chamber and features of the cornea. This information may then be
loaded into the
laser 3-D scanning system or used to generate a three dimensional
model/representation/image of
the cornea, anterior chamber, and lens of the eye, and used to define the
cutting patterns used in
the surgical procedure.
[0119] Observation of an aim beam can also be used to assist in
positioning the focus
point of the UF laser pulse beam 66. Additionally, an aim beam visible to the
unaided eye in lieu
of the infrared OCT sample portion beam 102 and the UF laser pulse beam 66 can
be helpful
with alignment provided the aim beam accurately represents the infrared beam
parameters. The
alignment guidance subsystem 48 is included in the assembly 62 shown in FIG.
3. An aim beam
108 is generated by an aim beam light source 110, such as a laser diode in the
630-650 nm range.
[0120] Once the aim beam light source 110 generates the aim beam 108, the
aim beam
108 is transmitted along an aim path 112 to the shared optics 50, where it is
redirected by a beam
combiner 114. After being redirected by the beam combiner 114, the aim beam
108 follows a
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shared path with the UF laser pulse beam 66 through the shared optics 50 and
the patient
interface 52. In this way, the aim beam 108 is indicative of the location of
the UF laser pulse
beam 66. The aim beam 108 passes through the Z-telescope 84, is redirected by
the X-scan
device 86 and by the Y-scan device 88, passes through the beam combiner 90,
passes through the
objective lens assembly 94 and the patient interface 52, and on into the
patient's eye 43.
[0121] The video subsystem 92 is operable to obtain images of the patient
interface and
the patient's eye. The video subsystem 92 includes a camera 116, an
illumination light source
118, and a beam combiner 120. The video subsystem 92 gathers images that can
be used by the
control electronics 54 for providing pattern centering about or within a
predefined structure. The
illumination light source 118 can be generally broadband and incoherent. For
example, the light
source 118 can include multiple LEDs. The wavelength of the illumination light
source 118 is
preferably in the range of 700 nm to 750 nm, but can be anything that is
accommodated by the
beam combiner 90, which combines the light from the illumination light source
118 with the
beam path for the UF laser pulse beam 66, the OCT sample beam 102, and the aim
beam 108
(beam combiner 90 reflects the video wavelengths while transmitting the OCT
and UF
wavelengths). The beam combiner 90 may partially transmit the aim beam 108
wavelength so
that the aim beam 108 can be visible to the camera 116. An optional
polarization element can be
disposed in front of the illumination light source 118 and used to optimize
signal. The optional
polarization element can be, for example, a linear polarizer, a quarter wave
plate, a half-wave
plate or any combination. An additional optional analyzer can be placed in
front of the camera.
The polarizer analyzer combination can be crossed linear polarizers thereby
eliminating specular
reflections from unwanted surfaces such as the objective lens surfaces while
allowing passage of
scattered light from targeted surfaces such as the intended structures of the
eye. The illumination
may also be in a dark-filed configuration such that the illumination sources
are directed to the
independent surfaces outside the capture numerical aperture of the image
portion of the video
system. Alternatively the illumination may also be in a bright field
configuration. In both the
dark and bright field configurations, the illumination light source can be
used as a fixation beam
for the patient. The illumination may also be used to illuminate the patient's
pupil to enhance the
pupil iris boundary to facilitate iris detection and eye tracking. A false
color image generated by
the near infrared wavelength or a bandwidth thereof may be acceptable.
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[0122] The illumination light from the illumination light source 118 is
transmitted
through the beam combiner 120 to the beam combiner 90. From the beam combiner
90, the
illumination light is directed towards the patient's eye 43 through the
objective lens assembly 94
and through the patient interface 94. The illumination light reflected and
scattered off of various
structures of the eye 43 and patient interface travel back through the patient
interface 94, back
through the objective lens assembly 94, and back to the beam combiner 90. At
the beam
combiner 90, the returning light is directed back to the beam combiner 120
where the returning
light is redirected toward the camera 116. The beam combiner can be a cube,
plate or pellicle
element. It may also be in the form of a spider mirror whereby the
illumination transmits past
the outer extent of the mirror while the image path reflects off the inner
reflecting surface of the
mirror. Alternatively, the beam combiner could be in the form of a scraper
mirror where the
illumination is transmitted through a hole while the image path reflects off
of the mirrors
reflecting surface that lies outside the hole. The camera 116 can be a
suitable imaging device,
for example but not limited to, any silicon based detector array of the
appropriately sized format.
A video lens forms an image onto the camera's detector array while optical
elements provide
polarization control and wavelength filtering respectively. An aperture or
iris provides control of
imaging NA and therefore depth of focus and depth of field and resolution. A
small aperture
provides the advantage of large depth of field that aids in the patient
docking procedure.
Alternatively, the illumination and camera paths can be switched. Furthermore,
the aim light
source 110 can be made to emit infrared light that would not be directly
visible, but could be
captured and displayed using the video subsystem 92.
[0123] FIG. 3B shows a mapped treatment region of the eye comprising the
cornea, the
posterior capsule, and the limbus. The treatment region can be mapped with
computer modeling,
for example ray tracing and phased based optical modeling to incorporate
factors such as laser
beam quality, pulse width, system transmission, numerical aperture,
polarization, aberration
correction, and alignment. The treatment volume is shown extending along the Z-
axis from the
posterior surface of the optically transmissive structure of the patient
interface a distance of over
15 mm, such that the treatment volume includes the cornea, and the lens in
which the treatment
volume of the lens includes the anterior capsule, the posterior capsule, the
nucleus and the
cortex. The treatment volume extends laterally from the center of the cornea
to beyond the
limbus. The lateral dimensions of the volume are defined by a Y contour
anterior to the limbus
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and by an X contour posterior to the limbus. The treatment volume shown can be
determined by
a person of ordinary skill in the art based on the teachings described herein.
The lateral positions
of predicted optical breakdown for ZL fixed to 30 mm and ZL fixed to 20 mm are
shown. These
surfaces that extend transverse to the axis 99 along the Z-dimension
correspond to locations of
optical scanning of the X and Y galvos to provide optical breakdown at lateral
locations away
from the axis 99. The curved non-planner shape of the scan path of optical
breakdown for ZL-30
mm and ZL-20 mm can be corrected with the mapping and look up tables as
described herein.
The curved shape of the focus can be referred to as a warping of the optical
breakdown depth and
the look up tables can be warped oppositely or otherwise adjusted so as to
compensate for the
warping of the treatment depth, for example. Additionally, the warping
inherent in the
prediction from the model can be incorporated in the generic look-up table and
any further error
from this predicted form as indicated by measurement and application of a
correction factor to
offset this error may also be called a warping of the look up table.
[0124] The treatment region is shown for setting the laser beam energy
about four times
the threshold amount for optical breakdown empirically determined for a beam
near the limbus
of the system. The increased energy or margin above ensures that the beam
system will be able
to treat given variability in contributing factors. Theses contributing
factors may include
degradation over lifetime of the laser with regard to energy, beam quality,
transmission of the
system, and alignment.
[0125] The placement of the posterior surface of the optically
transmissive structure of
the patient interface away from the surface of the cornea can provide the
extended treatment
range as shown, and in many embodiments the optically transmissive structure
comprises the
lens. In alternative embodiments, the posterior surface of the optically
transmissive structure can
be placed on the cornea, for example, and the mapping and look up tables as
described herein
can be used to provide the patient treatment with improved accuracy.
[0126] The optically transmissive structure of the patient interface may
comprise one or
more of many known optically transmissive materials used to manufactures
lenses, plates and
wedges, for example one or more of glass, BK-7, plastic, acrylic, silica or
fused silica for
example.
[0127] The computer mapping of the treatment volume may optionally be
adjusted with
mapping based on measurements of a constructed system as described herein.
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[0128] FIG. 4A shows correspondence among movable and sensor components
of the
laser delivery system 2. The movable components may comprise one or more
components of the
laser delivery system 2 as described herein. The movable components of the
laser delivery
system may comprise the zoom lens capable of moving distance ZL, the X galvo
mirror 96
capable of moving an angular amount Xõõ and the Y galvo mirror 88 capable of
moving an
angular amount Ym. The movable components of the OCT system may comprise the
movable
OCT reference arm configured to move the reference path 106 a distance ZED.
The sensor
components of the laser system may comprise the video camera having X and Y
pixels, Pix X
and Pix Y, respectively, and sensor components of the OCT system such as the
spectral domain
detection as described herein. The patient support which may comprise a bed is
movable in three
dimensions so as to align the eye 43 of the patient P with laser system 2 and
axis 99 of the
system. The patient interface assembly comprises an optically transmissive
structure which may
comprise an interface lens 96, for example, configured to be aligned with
system 2 and an axis of
eye 43. The patient interface lens can be placed on the patient eye 43 for
surgery, and the
optically transmissive structure can be placed at a distance 162 from the
objective lens 94. In
many embodiments, the optically transmissive structure comprises lens 96
placed a contact lens
optical distance 162 (hereinafter "CLopt"). The optically transmissive
structure comprises a
thickness 164, and the thickness 164 may comprise a thickness of the contact
lens 96, for
example. Although the optically transmissive structure comprising contact lens
96 may contact
the eye 2, in many embodiments the contact lens 168 is separated from the
cornea with gap 168
extending between the lens and the vertex of the cornea, such that the
posterior surface of the
contact lens 168 contacts a solution comprising saline or a viscoelastic
solution, for example.
[0129] FIG. 4B shows mapping of coordinate references from an eye space
coordinate
reference system 150 to a machine coordinate reference system 151 so as to
coordinate the
machine components with the physical locations of the eye. The laser system 2
can map
physical coordinates of the eye 43 to machine coordinates of the components as
described herein.
The eye space coordinate reference system 150 comprises a first X dimension
152, for example
an X axis, a second Y dimension 154, for example a Y axis, and a third Z
dimension 156, for
example a Z axis, and the coordinate reference system of the eye may comprise
one or more of
many known coordinate systems such as polar, cylindrical or Cartesian, for
example. In many
embodiments, the reference system 150 comprises a right handed triple with the
X axis oriented
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in a nasal temporal direction on the patient, the Y axis oriented superiorly
on the patient and the
Z axis oriented posteriorly on the patient. In many embodiments, the
corresponding machine
coordinate reference system 151 comprises a first X' dimension 153, a second
Y' dimension 155,
and a third Z' dimension 157 generally corresponding to machine actuators, and
the coordinate
reference system of the machine may comprise one or more of many known
coordinate systems
such as polar, cylindrical or Cartesian, and combinations thereof, for
example.
[0130] The machine coordinate reference 151 may correspond to locations
of one or
more components of system 2. The machine coordinate reference system 151 may
comprise a
plurality of machine coordinate reference systems. The plurality of machine
coordinate
reference systems may comprise a coordinate reference system for each
subsystem, for example.
For example, dimension 157 may correspond to movement of the z-telescope lens
capable of
moving distance ZL. The dimension 153 may correspond to movement of the X
galvo mirror 86
capable of moving an angular amount Xm, and the dimension 153 may correspond
to movement
of the Y galvo mirror 88 capable of moving an angular amount Ym. Alternatively
or in
combination, the dimension 157 may correspond to movable OCT reference arm
configured to
move the reference path 106 a distance ZED, along with dimension 157
corresponding to a
movement of the z-telescope for the OCT beam, and the dimension 153 and the
dimension 155
may correspond to movement of the X galvo mirror 86 and the Y galvo mirror 88,
respectively,
for the OCT beam. The dimension 151 may correspond to X pixels of the video
camera and
dimension 153 may correspond to Y pixels of the video camera. The axes of the
machine
coordinate reference system may be combined in one or more of many ways, for
example the
OCT reference arm movement of the reference path 106 the distance ZED can be
combined with
movement of the z-telescope lens capable of moving the distance ZL, for
example. In many
embodiments, the locations of the components of the laser system 2 are
combined when in order
to map the plurality of machine coordinate reference systems to the coordinate
reference system
150 of eye 43.
[0131] In the context of cataract surgery, the system may be configured
to perform
capsulotomy and lens fragmentation incisions as disclosed for instance, in
U.S. Patent No.
8,500,724, entitled "Method and Apparatus for Patterned Plasma-mediated Laser
Trephination of
the Lens Capsule and Three-dimensional Phaco-segmentation," which is
incorporated herein by
reference in its entirety. The system may likewise be configured to perform
one or more corneal
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incisions, including without limitation one or more cataract incisions,
sideport incisions or
relaxing incisions, as disclosed for instance in U.S. Patent Publ.
2008/0281303, entitled "Method
and Apparatus for Creating Ocular Surgical and Relaxing Incision," the
entirety of which is
incorporated herein by reference in its entirety.
[0132] The laser surgery system according to the present invention
preferably includes a
corneal topography subsystem. The corneal topography subsystem general refers
to those
portions of the laser surgery system which operate cooperatively to measure
the anterior corneal
topography of the eye and/or the posterior corneal topography to provide
information regarding
the anterior corneal surface and/or the posterior corneal surface. The corneal
surface
information, either anterior corneal surface information and/or posterior
corneal surface
information, preferably relates to at least one property of the selected
corneal surface affecting
the refractive characteristics of the eye.
[0133] In many embodiments, the method for obtaining corneal topography
measurements of the patient's eye comprises coupling a corneal topography
measurement
structure to a patient interface structure to place the topography measurement
structure in front of
the eye. The eye may be measured with the topography measurement structure and
the patient
interface away from the eye. The corneal topography measurement structure is
decoupled from
the patient interface structure. The patient interface structure is coupled to
a component of the
patient interface in order to contact the eye. In some embodiments, an
astigmatism axis of the
eye is determined in response to the measurement of the eye with the corneal
topography
structure removably coupled to the patient interface. In other embodiments,
the topography
measurement structure is permanently affixed to the laser surgical system.
[0134] In another aspect, embodiments provide an apparatus to measure an
eye. The
apparatus comprises a patient interface. A topography measurement structure is
configured to
couple to the patient interface to measure the eye without contacting the eye.
[0135] In many embodiments, corneal surface information may include an
axis, meridian
or structure that a physician or other user may wish to visually identify
without the aid of a user
interface, such as a display, and may desire visual markers (identifiers) to
be present near the
optical tissue of the eye being treated. In many embodiments, the axis,
meridian or structure of
the eye to be visualized may be marked with fiducial mark incisions on the
periphery of the eye
as described herein. The fiducial mark incisions preferably provide a visible
marker of the
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selected axis so that its location and orientation can be accurately
determined by visual
inspection. Visual inspection includes visual inspection under magnification,
such as by a
microscope.
[0136] For instance, in an astigmatic eye, a physician or other user may
wish to visualize
the steepest meridian of the cornea for alignment of a toric IOL within the
eye during cataract
surgery. The steepest meridian may be identified by a corneal topographer.
Radial fiducial
mark incisions disposed along the steep axis of the cornea of the patient's
eye are referred to
herein as toric fiducial mark incisions (or alternatively, "toric fiducial
marks"). The placement
of the toric fiducial mark incisions permits a treating physician to align a
toric IOL with the steep
axis of the eye during cataract surgery. Advantages of the toric fiducial
marks include the
reduction in manual error of placing a mark, the laser marks are visible for a
longer duration and
the number of measurements a patient-user need perform is minimized.
[0137] The fiducial mark incisions generally comprise two small, radial
incisions in the
cornea disposed at the periphery of the eye along the selected axis and
centered on one of the
limbus, iris or scanned capsule. The marks are preferably disposed 180 degrees
about the center
of the axis and more preferably are diametrically opposed. Fiducial mark
incisions may be
generated as two line segments defined by an intersection of a horizontal line
passing through a
center with a horizontal ring having an inner diameter defined by an optical
zone and a thickness
length and a width. These two line segments having a length (in microns) that
are x-y
projections of fiducial marks to be placed in the cornea, preferably
intrastromally and outside the
optical zone of the eye. Other shapes and placement of the fiducial marks are
shown herein in
Figs. 15-19 and the associated text and are described in U.S. Patent No.
14/255,430, filed April
17, 2014, entitled, "LASER FIDUCIALS FOR AXIS ALIGNMENT IN CATARACT
SURGERY,"
[0138] The fiducial mark incisions generally do not alter the optical
properties of the
cornea. Preferably, the length of the incision is less than 5 mm, preferably
less than 2.5 mm and
more preferably 1.5 mm or less. It has been found that an incision length of
1.5 mm or less
provides an optically visible incision that heals rapidly and does not alter
the optical properties
with a suitable margin of error. The pulse energy used in the producing the
fiducial mark
incisions is generally lower than what is used for capsulorhexis or
capsulotomy incisions, limbal
relaxing incisions and lens fragmentation, and is preferably between 0.5
microjoules and 8
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microjoules, more preferably between 3 microjoules and 10 microjoules and more
preferably
between 4 microjoules and 6 microjoules.
[0139] The axis, meridian or structure for which visual identification is
desired is
preferably measured by corneal topography or tomography. The corneal
topography
measurement structure may comprise an external illumination structure such as
a ring or disk
shaped illuminator that illuminates the eye to form a ring or disk shaped
virtual image of the
illumination structure, and the astigmatic axis of the cornea and the steepest
meridian are
determined based on measurements of the virtual image of the eye. The external
illuminator can
be configured to couple to the patient interface for measurement of the eye
and removed when
the eye has been docked to the patient interface.
[0140] After measurement by the corneal topographer, a patient
interface is
generally used to restrain the position of the patient's eye relative to the
system. Between
measurement of corneal topography and the placement of the patient interface,
the patient's eye
may have moved resulting in the movement of the axis, meridian or structure
for which visual
identification is desired. In many embodiments, iris registration is used to
determine a
cyclotorsional angle of the eye when the user interface is attached relative
to its non-contact
position during corneal topography measurements. For instance, a first image
of the iris is
obtained with a first camera prior to the patient interface contacting the
eye, and a second image
of the iris is obtained when the patient interface contacts the eye. The first
image and the second
image can be registered in one or more of many ways, and the processor can be
configured with
instructions to determine the cyclotorsional angle of the eye such as by image
matching
algorithm or a pattern recognition algorithm. The processor comprising the
instructions of the
algorithm can thus be configured to identify a pattern of the first image in
relation to an axis of
the eye as described herein and to identify the location of the pattern in the
second image in order
to determine the cyclotorsional angle of the eye, for example. The
cyclotorsional angle of the
eye can then be used to determine the position of the eye with patient
interface is attached,
including the axis, meridian or structure for which visual identification is
desired.
[0141] Thereafter, the fiducial mark incisions may be accurately incised
along the axis,
meridian or structure with the patient interface secured to the patients eye.
Additional incisions
by the laser surgical system may include one or more of a capsulotomy, limbal
relaxing
incisions, and lens fragmentation and/or segmentation patterns. After incision
of the relevant
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tissues is completed, the patient interface may be removed, and the lens may
subsequently be
removed.
[0142] FIG. 5A shows a flow chart of a method 300 for providing accurate
and
distortion-free corneal topography measurement and subsequent integration with
the laser
treatment, in accordance with embodiments. The method 300 comprises the
following main
steps. In a step 325, the patient's eye is positioned within the capture range
of the measurement
system of the laser eye surgery system 2 or 2A described herein. In a step
350, the measurement
system is used to measure corneal shape with high accuracy. Such a measurement
system may
comprise the ranging subsystem 46 described above. In a step 375, any changes
in the patient
eye orientation that may occur between the measurement time and the laser
treatment time is
accounted for.
[0143] Positioning step 325: In the step 325, the patient's eye is
positioned within the
capture range of the measurement system of the laser eye surgery system as
described herein,
such as shown in Figs. 2 and 3A, for example. Positioning of the patient for
laser surgery is
typically enabled by motion of the patient bed 34 or by motion of the laser
system 2. Typically,
the operator has manual control of the lateral and axial position, guiding the
docking mechanism
or patient interface 52 into place in a step 328. In the absence of a docking
mechanism, an
operator means for guiding the motion so that the eye, and specifically the
cornea, is placed
within the operative range of the measurement system may be provided. This can
be
accomplished with the use of subsystems of the laser system 2 or 2a described
herein such as
alignment guidance system 48 of laser system 2 or imaging subsystem 346 of
laser system 2a.
Initial patient position can be guided by a video camera, guiding the eye into
lateral position by
centering the video image, and into axial position by focusing the image. At
this point, the
cornea is placed within the capture range of the OCT system of the ranging
subsystem 46 or
imaging subsystem 546, typically X mm to Y mm axially, in a step 331. The OCT
system can be
used to measure the axial position of the cornea in a step 334, and a suitable
display provides the
operator guidance for final, accurate positioning. Alternatively, a visual
imaging system such as
a camera, a camera coupled to a microscope which may share optics with the
laser system 2 or
2a, a CCD, among others may be used instead of the OCT system to facilitate
the positioning
step 325.
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[0144] Since the video and OCT systems are typically configured to
operate with the
docking system, which often has additional optical elements and liquid medium
in the optics
path, the focusing algorithms of the laser system may be adjusted to account
for operation
without the docking mechanism optics and interface medium.
[0145] Measurement step 350: In the step 350, the measurement system is
used to
measure corneal shape with high accuracy. The laser system 2 or 2A comprises a
subsystem for
mapping the ocular surfaces that are being treated such as the ranging
subsystem 46 having an
OCT system described herein or the imaging subsystem 546. As described below,
the imaging
subsystem 546 may apply other modalities for mapping the ocular surfaces such
as Placido
imaging, Hartmann-shack wavefront sensing, confocal tomography, low coherence
reflectometry, among others. The measurement step 350 can be performed once
the eye is
positioned correctly in the step 325 above. A fixation light can optionally be
introduced to help
the patient keep the eye pointed at a fixed angle. If the measurement data
capture is sufficiently
fast, for example, on the order of one second, a fixation light may not be
necessary. In a step 353
of measurement 550, multiple OCT or other scans of the cornea surfaces can be
acquired in a
short time. Multiple scans can increase the confidence of obtaining good data.
In a step 356,
post-processing of the scans can remove potential eye motion and further
improve the
measurement accuracy. In a step 362 of measurement step 350, corneal power can
be measured
from camera images of reflected light from the cornea.
[0146] Once the cornea surfaces have been mapped, polynomial, or other
fitting
algorithms can be used to calculate commonly used parameters of the cornea in
a step 359.
Commonly used parameters include the optical power of the cornea, astigmatic
axis angle, and
astigmatism magnitude.
[0147] Coordinate system transfer step 375: In the step 375, any changes
in the patient
eye orientation that may occur between the measurement time and the laser
treatment time is
accounted for. Often times, it is probable that when the patient eye is docked
for treatment such
as with the suction ring of the patient interface 52, the eye, including its
various anatomical
features, will change its position relative to the laser system coordinates.
This change can be a
result of patient head movement, eye movement, or because of force applied
during docking. In
some cases, the refractive properties of the air or any liquid over the eye
can distort the images of
the eye. For example, the suction ring of the patient interface 52 may be
filled with one or more
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of a solution, saline, or a viscoelastic fluid. It can be helpful to transform
the corneal
measurements, like the astigmatic axis angle, to a new coordinate system to
account for any
movement and distortion. Several means for accomplishing this are provided.
[0148] In some embodiments, the operator can mark the patient eye prior
to the
measurement with ink dots that are typically positioned diametrically across
on the periphery of
the cornea in a step 378. These dots can be acquired by the imaging camera
after docking for
treatment and used for calculating the coordinate transformation in a step
381.
[0149] In other embodiments, ocular features that are visible in the
video images, or the
OCT or other scans, taken during the measurement step are used. These features
are correlated
to the images taken after docking for treatment in a step 384. This
correlation can be done by
digital image processing algorithms, or manually by the operator. When done
manually, the
operator is presented by overlapped images (measurement and treatment steps)
on the control
screen, and the images are manually manipulated in translation and rotation
until they are visibly
matched. The image manipulation data can be detected by the display software
and used for the
coordinate transform.
[0150] Although the above steps show method 500 of providing accurate and
distortion-
free corneal topography measurement and subsequent integration with the laser
treatment in
accordance with many embodiments, a person of ordinary skill in the art will
recognize many
variations based on the teaching described herein. The steps may be completed
in a different
order. Steps may be added or deleted. For example, the shape of the cornea may
be measures
before, during, or after docking for treatment such as with a suction ring of
the patient interface
52. Many of the steps may be repeated as often as beneficial to the method.
[0151] One or more of the steps of the method 500 may be performed with
the circuitry
as described herein, for example, one or more the processor or logic circuitry
such as the
programmable array logic for field programmable gate arrays. The circuitry may
be
programmed to provide one or more of the steps of method 500, and the program
may comprise
program instructions stored on a computer readable memory or programmed steps
of the logic
circuitry such as the programmable array logic or the field programmable gate
array, for
example.
[0152] FIG. 5B shows a laser eye surgery 2A similar to system 2 of FIG. 2
in accordance
with embodiments. The laser eye surgery system 2 is similar to the laser eye
surgery system 2 as
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described herein and comprises many of the same components. In particular, the
laser eye
surgery system 2A comprises an imaging subsystem 646 which may be used to
visualize and
image the eye 43, and the control panel/GUI 56 comprises a display 56A. The
laser eye surgery
system 2A may be configured to couple to a separate and distinct ancillary
diagnostic system
648. For the laser eye surgery system 2, the OCT system of the ranging
subsystem 46 may be
used to position the patient eye in the step 325 and/or to measure the shape
of the cornea in the
step 350. For the laser eye surgery system 2A, the ancillary diagnostic system
648 is used to
measure the shape of the cornea in the step 350. The ancillary diagnostic
system 648 may apply
any number of modalities to measure the shape of the eye including one or more
of a
keratometry reading of the eye, a corneal topography of the eye, an optical
coherence
tomography of the eye, a Placido disc topography of the eye, a reflection of a
plurality of points
from the cornea topography of the eye, a grid reflected from the cornea of the
eye topography, a
Hartmann-Shack topography of the eye, a Scheimpflug image topography of the
eye, a confocal
tomography of the eye, or a low coherence reflectometry of the eye. The shape
of the cornea can
be measured before, during, or after the patient interface 52 is docked with
the eye of the patient.
The shape of the cornea may be measured using the ancillary diagnostic system
648 while the
ancillary diagnostic system 648 is separate from the laser eye surgery system
2A, such as by
being in a different room. Images captured by the ranging subsystem 46 of the
laser eye surgery
system 2 or the imaging subsystem 546 of the laser eye surgery system 2A and
the ancillary
diagnostic system 548 may be displayed with a display of the control panel/GUI
56 of the laser
eye surgery system 2 or the display 56A of the laser eye surgery system 2A,
respectively. The
control panel/GUI 56 may also be used to modify, distort, or transform any of
the displayed
images.
[0153]
FIGS. 8A-8D show a corneal topography measurement structure configured to
couple to a patient interface 52 as described herein to measure the eye prior
to the eye contacting
the patient interface. The topography measurement structure may comprise one
or more of a ring
or other structure for a keratometry reading of the eye, a Placido disc
topography of the eye, a
reflection of a plurality of points from the cornea topography of the eye, a
grid reflected from the
cornea of the eye topography. In many embodiments, the measurement structure
comprises a
Placido disc structure configured to couple to a component of the patient
interface, for example.
The topography measurement structure can be illuminated, for example, so as to
form a virtual
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image of the measurement structure when reflected from the cornea. One
illumination strategy
could make use of the internal existing illuminator of the system itself.
Alternatively or in
combination, the topography structure may comprise a ring illuminator either
mounted to the
patient interface or to the structure of the laser system.
[0154] In many embodiments, topography measurement structure is back
illuminated
with light from the laser system to illuminate the eye with the topography
measurement
structure. Alternatively or in combination the topography measurement
structure may comprise
a plurality of light sources such as light emitting diodes to illuminate the
eye with the topography
measurement structure.
[0155] FIG. 8B shows the topography measurement structure removable
coupled to the
patient interface to position the topography measurement structure in relation
to the eye when the
patient has been placed on the support of the laser eye surgery system as
described herein. The
OCT measurement beam can be used to position the eye. This use of the OCT
measurement
beam may be particularly important to achieve absolute curvature readings of
the Placido system
as the diameter of the reflected Placido rings may depend not only on the
curvature of the cornea
but also from the distance of the ring illuminator and the cornea. OCT can
help to minimize
these variations. Additionally, this measurement information can also be used
to actively track
position the patient's chair and move the eye into the correct or desired
position. Additionally,
the OCT system and optionally also the camera can be used to locate the actual
position of the
Placido ring in relation to the system to enable high precision measurements.
Alternatively or in
combination, the focus of the video camera as describe herein can be used to
position the eye for
measurement. When the topography of the patient has been measured and the axis
determined,
for example, the topography measurement system can be decoupled from the
patient interface
structure and the patient interface coupled to the eye as described herein.
[0156] The Placido disk illuminator can be constructed in many different
ways. Having a
clear aperture in the center of the ring structure to allow the video system
to be used as is may be
particularly important. Other embodiments may comprise a combination of
different engineered
diffusers and masks which can be optimized on the diffusing angle used to the
detection of the
rings from the cornea. Or, if polarized light is used, a combination of
quarter wave plate or
depolarizer and diffuser with ring apertures can be used. For full
utilization, the light illuminated
on the blocked rings can make the blocked rings act as reflecting wedges so
the light is fully
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utilized. In such cases, an angle which enables total reflection may be
helpful. Utilizing a
combination of a strong negative lens and the Placido disk illuminator can
also increase the light
intensity of the outer rings for better contrast.
[0157] In many embodiments, the topography measurement structure
comprises an
external illumination structure such as a ring illuminator illuminates the eye
to form a ring
shaped virtual image of the illumination structure, and the astigmatic axis of
the eye determined
based on measurements of the virtual image of the eye as described herein. The
external
illuminator can be configured to couple to the patient interface for
measurement of the eye and
removed when the eye has been docked to the patient interface. Alternatively,
the external
illuminator may comprise a substantially fixed structure that remains fixed to
the laser system
throughout a plurality of procedures.
[0158] The corneal topography data and thickness data can be combined in
one or more
of many ways. For example, the corneal topography data can be used to
determine the shape
profile of the anterior corneal surface, and the corneal thickness profile
data can be fit to the
anterior corneal surface profile in order to determine the profile of the
posterior surface, for
example. In many embodiments, the anterior corneal surface profile is measured
and determined
without the patient interface contacting the eye, and the corneal thickness
profile is measured and
determined when the patient interface contacts the eye. The corneal surface
profile data
measured without contacting the eye can be combined with the corneal thickness
profile data
measured with the patient interface contacting the eye, and the location of
refractive incisions
determined in response to both profiles, for example.
[0159] FIG. 8B shows components of the patient interface and the
topography
measurement structure configured to couple to the patient interface.
[0160] In some embodiments, corneal thickness maps may be generated in
order to
determine posterior corneal surface information.
[0161] FIGS. 6A to 6C show images of the eye which may be displayed for
example in
the display 56A of the laser eye surgery system 2A or the display of the laser
eye surgery system
2, for example. The images shown illustrate distortion which may occur and the
distortion may
not be to scale and is provided for illustration purposes in accordance with
embodiments.
[0162] FIG. 6A shows a coordinate system 600A overlaid on an image 601A
of an eye
EY. The image 601A of the eye 43 shows various anatomical features including
the sclera
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43SC, the limbus 43LI, the iris 431, and the pupil 43PU. Similar images and
biometric
information can be obtained with similar maps. In many embodiments, this image
601A can be
captured by the imaging subsystem 546 of the laser eye surgery system 2A. The
image 601A is
captured prior to coupling the eye with a suction ring of the patient
interface 52 of the laser eye
surgery system 2. The image 601A may most accurately represent the positions
of the various
tissue structures of the eye 43. The image 601A may comprise one or more of
many images or
measurements as described herein. A person of ordinary skill in the art will
recognize that the
pupil seen through the cornea/air interface comprises a virtual pupil of the
eye. Although the
shape and optical power of the cornea may provide distortion and magnification
of the pupil and
iris, a person of ordinary skill in the art can correct this distortion and
magnification based on the
teaching described herein and in accordance with embodiments as appropriate.
For example, the
virtual image of the pupil can be transformed to an eye space coordinate
system 150 as described
herein.
[0163] The structures shown in coordinate system 600A can be transformed
to the
coordinate reference system 150 of eye 2 in one or more of many ways. For
example, the tissue
structures shown in the image such as the limbus and the iris can be
identified, and the transform
to the eye coordinate reference system 150 determined based on the location of
the tissue
structure and depth and location in relation to correspondence optical tissue
surfaces such as the
surface of the cornea. The locations of the tissue structures identified in
the image 601 can be
determined and mapped to eye coordinate reference system 150 or to one or more
coordinate
reference systems as described herein.
[0164] In many embodiments, iris registration is used to determine a
cyclotorsional angle
of the eye. A first image of the iris can be obtained with a first camera
prior to the patient
interface contacting the eye, and a second image of the iris can be obtained
when the patient
interface contacts the eye. The first camera image of the iris can be
registered with the second
camera image of the iris of the patient in order to determine the cyclo
torsional angle of the eye
as described herein. In many embodiments, the first non-contact image of the
eye comprises an
image of the iris wherein the cornea of the eye magnifies and may distort the
virtual image of the
iris seen with the camera, and the second contact image of the eye comprises
an image of the eye
measured when the patient interface contacts the eye. The first image and the
second image can
be registered in one or more of many ways, and the processor can be configured
with instructions
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to determine the cyclotorsional angle of the eye with instructions of an
algorithm such as one or
more of an image matching algorithm or a pattern recognition algorithm, for
example. The
processor comprising the instructions of the algorithm can be configured to
identify a pattern of
the first image in relation to an axis of the eye as described herein and to
identify the location of
the pattern in the second image in order to determine the cyclotorsional angle
of the eye, for
example.
[0165] In many embodiments, ray tracing through the full thickness
corneal profile map
can be used to correct distortions of the cornea, such as one or more of
distortions of the anterior
corneal surface of the posterior corneal surface. For example, when the eye
has been docked and
the fluid of the patient interface contacts the eye, distortions of the
posterior surface of the eye
can influence light rays travelling through the cornea, and distortions of
images of tissue
structure posterior to the posterior surface of the cornea can be corrected in
response to ray
tracing. The ray tracing can be performed by a person of ordinary skill in the
art using Snell's
law and the index of refraction of the cornea and contacting material such as
air, interface fluid,
or aqueous humor, for example. Alternatively or in combination, distortions of
the anterior
corneal surface and the corresponding distortion of images measured through
the cornea can be
corrected with ray tracing, for example when the cornea is exposed to air.
While distortions of
the anterior corneal surface can be corrected in a manner similar to the
posterior surface with ray
tracing, work in relation to embodiments suggests that coupling the eye to the
patient interface
with a fluid contacting the patient interface and having an index of
refraction similar to the
cornea can decrease the effect of distortions of the anterior corneal surface.
Based on the
teachings disclosed herein, a person of ordinary skill in the art can
determine and correct for
distortions of images of the eye related to corneal distortions with ray
tracing and corneal profile
maps as described herein, for example.
[0166] In many embodiments one or more of the first image or the second
image is
adjusted in response to distortion of the one or more of the first image or
the second image. The
distortion can be related to the index of refraction viscous fluid into the
patient interface that
affects the optical properties of the image of the eye, or the distortion of
the optical delivery
system, and combinations thereof. In many embodiments, the distortion of the
cornea can be
determined in response to a thickness profile of the cornea, and aberrations
of the image
introduced by the thickness profile of the cornea corrected.
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[0167] FIG. 6A1 shows corneal profile data 610A of cornea 43C for the
coordinate
system and image of FIG. 6A. The corneal profile data 610A comprises a
plurality of corneal
profiles from the tomography system taken with the patient interface away from
the eye as in
FIG. 6A. The plurality of corneal profiles comprises a first corneal profile
612A, a second
corneal profile 614A and a third corneal profile 616A. Additional corneal
profiles can be taken.
The cornea profiles can be obtained with tomography scans along a plane for
example, and
detection of the corneal surface. The corneal surface can be fit as described
herein, for example
with polynomials as described herein. The fit corneal surface can be used to
determine the
corneal topography and treatment parameters as described herein. The corneal
profile data may
comprise coordinate system 600A, for example.
[0168] FIG. 6B shows a distorted coordinate system 600B overlaid on the
eye image
601B of the eye 43. The image 601A of the eye 43 shows various anatomical
features including
the sclera 43SC, the limbus 43LI, the iris 431, and the pupil 43PU. In many
embodiments, this
image 601B is taken of the eye by a visual imaging system of the laser eye
surgery system 2.
This image 601B is taken when the anterior surface of the eye 43 is coupled
with a suction ring
of the laser eye surgery system 2 to expose the anterior surface to air. The
suction ring may
distort the tissue structures of the eye 43 when placed thereon. The locations
of the various
tissue structures of the eye, such as one or more structures of the iris, in
relation to the distorted
coordinate system 600B can be mapped to their respective locations the
coordinate system 600A
in image 601A to account for this distortion.
[0169] FIG. 6C shows a distorted coordinate system 600C overlaid on the
eye image
601C of the eye 43. The image 601C of the eye 43 shows various anatomical
features including
the sclera 43SC, the limbus 43LI, the iris 431, and the pupil 43PU. In many
embodiments, this
image 601C is taken of the eye by a visual imaging system of the laser eye
surgery system 2.
This image 601C is taken when the anterior surface of the eye 43 is coupled
with a suction ring
of the laser eye surgery system 2 and the suction ring is filled with a liquid
such as saline or
viscoelastic substance. In addition to distortion from interfacing with the
suction ring, the
refractive properties of the liquid may also distort light reflecting back
from the anterior surface
of the eye EY. The locations of the various tissue structures of the eye, such
as one or more
structures of the iris, in relation to the distorted coordinate system 600C
can be mapped to their
respective locations the coordinate system 600A in image 601A to account for
these distortions.
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Alternatively or in combination, the structures can be mapped to eye
coordinate reference system
150
[0170] FIG. 6C1 shows corneal profile data 610C of cornea CO for the
coordinate system
and image of FIG. 6C. The corneal profile data 610C can be provided with
mapping of the
corneal profile data 610A, or based on a second set of similar measurements.
The corneal profile
data 610C comprises a plurality of corneal profiles from the tomography system
taken with the
patient interface away from the eye as in FIG. 6A. The plurality of corneal
profiles comprises a
first corneal profile 612C, a second corneal profile 614C and a third corneal
profile 616C.
Additional corneal profiles can be taken. The cornea profiles can be obtained
with tomography
scans along a plane for example, and detection of the corneal surface. The
corneal surface can
be fit as described herein, for example with polynomials as described herein.
The corneal profile
data 610C may a coordinate system 600C overlaid. The corneal profile data 610C
of coordinate
system 600C may be mapped to eye coordinate reference 150 as described herein,
for example.
Alternatively or in combination, the corneal profile data 610C may comprise
eye coordinate
reference 150 as described herein, for example when the treatment is mapped
based on the
patient interface coupled to the eye.
[0171] In many embodiments, the non-distorted image 601A is modified to
provide a
distorted first image with a distortion similar to that in images 601B or
601C. The distorted
image 601A may then be displayed on the display 56A or other display of the
laser eye surgery
system 2 or 2A. A user of the laser eye surgery system 2 or 2A can adjust one
or more of a
location or an angle of the distorted image 601A on the display 56A or other
display. Locations
of a plurality of laser beam pulses from the cutting laser subsystem 44 can
then be adjusted in
response to the location or the angle of the first distorted image 601A on the
display 56A or other
display. In some embodiments, the distorted first image 601A is overlaid on
the distorted image
601B or 601C on the display 56A or other display to determine the position and
the angle of the
eye for treatment. A processor of the laser eye surgery system 2 or 2A can
determine the
position and the angle of the distorted first image 601A on the display in
response to user input
to adjust the locations of the plurality of laser beam pulses from the cutting
laser subsystem 44.
[0172] FIG. 6A2 shows corneal thickness profile data for the coordinate
system and
images of FIGS. 6A and 6A1. The corneal profile data 610A comprises a
plurality of corneal
thickness profiles from the tomography system taken with the patient interface
away from the
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eye as in FIG. 6A. The plurality of corneal profiles comprises a first corneal
thickness profile
617A, a second corneal thickness profile 618A and a third corneal profile
619A. Additional
corneal profiles can be taken.
[0173] Each of the thickness profiles may comprise a difference between
an anterior
surface profile and a posterior surface profile, for example. The first
corneal thickness profile
617A may comprise a difference between a first anterior surface profile 612A
and a first
posterior surface profile 611A. The second corneal thickness profile 618A may
comprise a
difference between second anterior surface profile 614A and a second posterior
surface profile
613A. A third corneal profile 619A may comprise a difference between third
anterior surface
profile 616A and a third posterior surface profile 615A. Additional corneal
profiles can be
taken.
[0174] Each of the corneal thickness profiles coordinate system 600ACof
can be mapped
to the physical eye coordinate reference system 150.
[0175] FIG. 6C2 shows corneal thickness profile data for the coordinate
system and
images of FIGS. 6C and 6C1. The corneal thickness profile data 610A comprises
a plurality of
corneal thickness profiles from the tomography system taken with the patient
interface away
from the eye as in FIG. 6C. The plurality of corneal profiles comprises a
first corneal thickness
profile 617C, a second corneal thickness profile 618C and a third corneal
profile 619C.
Additional corneal profiles can be taken.
[0176] Each of the thickness profiles may comprise a difference between
an anterior
surface profile and a posterior surface profile, for example. The first
corneal thickness profile
617C may comprise a difference between a first anterior surface profile 612C
and a first
posterior surface profile 611C. The second corneal thickness profile 618C may
comprise a
difference between second anterior surface profile 614C and a second posterior
surface profile
613C. A third corneal profile 619C may comprise a difference between third
anterior surface
profile 616C and a third posterior surface profile 615C. Additional corneal
profiles can be taken.
[0177] Each of the corneal thickness profiles coordinate system 600Cof
can be mapped
to the physical eye coordinate reference system 150.
[0178] FIG. 6A3 shows a corneal thickness profile map 620A for the
coordinate system
and images of FIG. 6A, 6A1 and 6A2. The thickness profile map generally
comprises a
representation of three dimensional thickness profile data of the cornea, and
may comprise three
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dimensional thickness data of the cornea. For example, the thickness profile
data may comprise
a two dimensional array in which the thickness of the cornea is stored for
each two dimensional
location of the array.
[0179] The corneal thickness profile map 620 can be determined based on
the first
corneal thickness profile 617A, the second corneal thickness profile 618A and
the third corneal
thickness profile 619A, for example. The corneal thickness profile map 620A
can be shown in
relation to the pupil 43PU and the limbus 43LI. The cornel thickness profile
map 620A can be
displayed to the user in one or more of many known formats such as with color
coding of
thicknesses or with equal depth contour lines. The equal depth contour lines
may comprise a
first equal depth contour line 622A, a second equal depth contour line 624A.
The corneal
thickness profile data can be fit as described herein, for example with a
polynomial as described
herein, in order to provide the corneal thickness profile map 620. The maps
can be obtained with
reference to coordinate system 600A and mapped to eye coordinate reference
system 150, for
example.
[0180] FIG. 6C3 shows a corneal thickness profile map 620C for the
coordinate system
and images of FIG. 6C, 6C1 and 6C2. The corneal thickness profile map 620C can
be
determined based on the first corneal thickness profile 617C, the second
corneal thickness profile
618C and the third corneal thickness profile 619C, for example. The corneal
thickness profile
map 620C can be shown in relation to the pupil 43PU and the limbus 43LI. The
cornel thickness
profile map 620C can be displayed to the user in one or more of many known
formats such as
with color coding of thicknesses or with equal depth contour lines. The equal
depth contour
lines may comprise a first equal depth contour line 622C, a second equal depth
contour line
624C. The corneal thickness profile data can be fit as described herein, for
example with a
polynomial as described herein, in order to provide the corneal thickness
profile map 620. The
maps can be obtained with reference to coordinate system 600C and mapped to
eye coordinate
reference system 150, for example.
[0181] Work in relation to embodiments of the present disclosure suggest
that the corneal
thickness profile maps and data as disclosed herein are resistant to
mechanical deformation when
the suction ring is placed on the eye, and can be used to align the eye about
the cyclotorsion al
axis, for example. The corneal thickness profile maps can be particularly well
suited to align
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eyes having prior refractive surgery, such as eyes that have received LASIK or
PRK or other
refractive surgery, for example.
[0182] The laser surgery system according to the present invention
preferably includes an
axis determining subsystem. The axis determination subsystem general refers to
those portion
of the laser surgery system 2 which operate cooperatively to identify and
measure axis
information regarding one or more ophthalmic axes of the eye. The axis
information preferably
comprises the location of the selected axis. The one or more selected
ophthalmic axes may be of
one or more of an optical axis, a treatment axis a visual axis and a fiducial
marker axis.
[0183] FIGS. 7A and 7B show side views of a plurality of axes of the eye
43 when the
eye views a fixation target and the eye is measured with an imaging system 646
prior to
contacting a patient interface. The imaging system 646 can be used to measure
one or more
optical structures of the eye, and the processor of the laser system can be
used to determine
locations of the incisions in response to locations of the one or more optical
structures. The
imaging system 646 may comprise one or more components of the ranging system
46 as
described herein alignment and may comprise one or more components of guidance
system 48 as
described herein, for example the OCT system of ranging system 46 and video
camera of
alignment guidance system 48. Alternatively or in combination, the imaging
system 646 may
comprise one or more components of separate diagnostic system 648 as described
herein. The
imaging system 646 may by located on laser system 2, or may comprise separate
and distinct
ancillary diagnostic system 648, and combinations thereof, for example.
[0184] Imaging system 646 can be aligned with one or more axes of the eye
as described
herein, for example with the patient viewing the fixation light 119. In many
embodiments, the
patient views fixation light 119, and the imaging system 646 is aligned with
the eye in one or
more of many ways as described herein.
[0185] Imaging system 648 comprises fixation light 119 as described
herein for the
patient to view when measurements are obtained. The fixation light 119 allows
the patient to
fixate in order to align the axes of the coordinate system 150 of the eye with
one or more
reference axes of the coordinate system 650 of imaging system 646. The imaging
system may
648 comprise a measurement axis 699 that extends along an optical axis of the
measurement
system, and the fixation light 119 can be located along the measurement axis
699 to align the eye
with the measurement system. The measurement axis 699 may comprise axis 99 of
the optical
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delivery system of laser system 2 when laser system 2 is used for measurements
of the eye prior
to contacting the eye with the patient interface. The initial measurement
reference coordinate
system 650 of imaging system 646 comprises a first dimension 652, a second
dimension 654 and
a third dimension 646, for example. The dimensions of the coordinate system
650 may comprise
a right handed triple orthogonal coordinate reference system, for example. The
third dimension
646 may comprise the measurement axis 699 of the measurement system, for
example. For
initial measurements of the eye prior to the patient interface contacting the
eye, the coordinate
reference system may comprise the eye coordinate reference system 150 as
described herein.
When the eye has been contacted with the patient interface, the eye coordinate
reference system
150 for treatment with the laser can be one or more of rotate or translated
with respect to the
initial measurement reference coordinate system 650.
[0186] The imaging system 646 includes sensors to image one or more
tissue structures
of the eye and can be used to determine one or more axes of the eye as
described herein. The
imaging system 646 can image and profile one or more structures of the eye as
described herein,
such as one or more of the cornea of the eye 43C, the anterior surface of the
cornea, the posterior
surface of the cornea, the iris of the eye 431, the pupil of the eye 43PU, the
natural pupil of the
eye 43PUN, the lens of the eye 43L, the anterior capsule of the lens 43LAC,
the posterior
capsule of the lens 43LPC, the entrance pupil of the eye 43ENP, the natural
entrance pupil of the
eye, the vertex of the cornea 43VX. In many embodiments, tomography of the
cornea is
combined with surface topography of the cornea and the video camera images of
the cornea to
determine one or more axes of the eye 43.
[0187] The vertex 43VX of the cornea may comprise a central part of the
cornea located
along the optical axis 43A0 of the eye that extends substantially
perpendicular to the plane of the
eye, and may comprise a center of the cornea as determined in response to a
measurement of the
limbus extending around the perimeter of the cornea.
[0188] The imaging system 646 can be used to determine one or more
optical structures
of the eye when the eye fixates naturally without contacting the patient
interface in order to
determine locations of the one or more optical structures of the eye when the
eye contacts the
patient interface. In many embodiments, the imaging system 646 is used to
determine one or
more of the optical axis of the eye 43A0, the center of curvature of the
anterior corneal surface,
the center of curvature of the posterior corneal surface, the center of
curvature of the lens capsule
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anterior surface, or the center of curvature of lens capsule posterior
surface. The optical axis of
the eye may comprise a straight line extending from the center of curvature of
the anterior
surface of the cornea to the center of curvature of the posterior surface of
the posterior lens
capsule. In many embodiments, the centers of curvature may not lie on a
straight line, and the
processor of the laser eye surgery system can be used to determine the optical
axis 43A0 with an
orientation and location that decreases the distance from the optical axis to
each of the center of
curvature of the cornea anterior surface, the center of curvature of the
cornea posterior surface,
the center of curvature of the lens capsule anterior surface, and center of
curvature of the capsule
posterior surface, for example, with least squares fitting of the optical axis
to the centers of
curvature for example.
[0189] The curvatures and the centers of curvature of the eye can be used
to determine
the locations of the cardinal points of the eye comprising the object point
where the fixation light
119 is located, the image point where the center of the fovea 43FV is located
when the patient
views the fixation light, the anterior nodal point 43NA of the eye, the
posterior nodal point
43NP, the anterior principal point 43AP, and the posterior principal point
43PP. One or more of
these cardinal points of the eye can be used to determine incision locations
of the pulsed laser
beam, and these cardinal points and the corresponding axes can be shown on a
display to a user
to determine locations on the incisions, in accordance with many embodiments.
[0190] One or more of the natural entrance pupil 43ENP or the natural
exit pupil 43EXP
of the eye can be determined and may be used to determine locations of the
incisions with the
pulsed laser beam. The entrance pupil 43ENP of the eye comprises a virtual
image of the pupil
of the eye as seen by light rays entering the eye from the fixation light 119.
The natural exit
pupil of the eye 43EXP may comprise the image of the iris 431 formed by lens
431 as seen from
the fovea.
[0191] Referring to FIG. 7B, the cardinal points of the eye and image
forming axes of the
eye are shown in detail. The iris 431 can be seen in relation to the physical
pupil center 43PC,
the location of the center of the entrance pupil 43ENP along the optical axis
43A0, and the
location of the center of the exit pupil 43EXP along the optical axis 43A0.
The visual axis
43VA is shown extending from the fixation light to the anterior node 43NA, and
from the
posterior node 43NP to the center of the fovea, with the first and anterior
node separated from
the second and posterior node along the optical axis 43A0. The line of sight
43L0S can be seen
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extending from the fixation light 119 to the center of the entrance pupil
43ENP, and from the
center of the exit pupil 43EXP to the center of the fovea, with the center of
the entrance pupil
and the center of the exit pupil located along the optical axis.
[0192] The axes of the eye that can be identified and determined with the
imaging system
646 or the processor of laser system (and combinations thereof) include a
fixation axis 43FA, a
visual axis 43VA, a line of sight 43L0S, a pupillary axis 43PA and an optical
axis 43A0.
[0193] The 43FA fixation axis of the eye may comprise an axis extending
from the
fixation light 119 through a center of rotation of the eye 43C.
[0194] The line of sight 43L0S may comprise a straight line extending
from the fixation
light through the center of the entrance pupil 43EP when the patient views the
fixation light. The
line of sight 43L0S may also comprise a straight line extending from the fovea
to the exit pupil
of the eye when the patient views the fixation light. The entrance pupil P
comprises a virtual
image of the pupil that the light rays from the fixation light entering the
eye are directed toward,
and can be imaged with the video camera of the alignment assembly 48 as
described herein. The
exit pupil 43EXP comprises
[0195] The pupillary axis 43PA may comprise a line perpendicular to the
surface of the
cornea, passing through the center of the pupil, for example.
[0196] The visual axis of the eye may comprise one or more of many axes
of the eye, in
accordance with embodiments as described herein. In many embodiments the
visual axis
comprises an axis extending from the fixation light 119 to the anterior
optical nodal point of the
eye N, in which the anterior optical nodal point of the eye N is located along
the optical axis of
the eye 43A0. The visual axis of the eye can extend from the posterior nodal
point of the eye
43NP to the center of the fovea FV, with an angle a (Alpha), extending between
the optical axis
and the visual axis.
[0197] Alternatively, the visual axis of the eye may comprise an
imaginary straight line
passing from the fixation light located at the midpoint of the visual field,
through the pupil, to the
center of the fovea 43FV when the patient fixates on the fixation light, for
example. A person of
ordinary skill in the art, based on the teachings of the present disclosure,
will recognize that the
imaginary straight line of the visual axis can be approximated by a line
extending between the
anterior nodal point of the eye and the posterior nodal point of the eye, for
example
approximated with a single "nodal" point of the eye. For example, the eye may
comprise a
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single index of refraction to provide the single nodal point of the eye, for
example with
Gullstrand's reduced schematic eye model. However, in many embodiments as
described herein
the eye comprises two or more indices of refraction, for example three or more
indices of
refraction, and the image guided treatment as described herein will provide
treatment planning to
the user in response to identification of the visual axis of the eye extending
from the anterior
nodal point of the eye to the fixation target and from the posterior nodal
point of the eye to the
fovea.
[0198] An angle y (Gamma) can extend between the optical axis and the
fixation axis, for
example. An angle lc (Kappa) can extend between the visual axis 43VA and the
pupillary axis
43PA, for example. Alternatively, angle lc (Kappa) can be defined so as to
extend between the
pupillary axis 43PA and the line of sight, for example. In many embodiments,
the pupillary axis
comprises a line extending normal to the surface of the cornea and through the
center of the
pupil, for example.
[0199] FIG. 7C shows an anterior view of an eye 43 as in FIGS. 7A and 7B.
The view
shows structure of the eye similar to the views of FIGS. 7A and 7B. In many
embodiments, the
images of FIGS. 7A and 7B are obtained with a tomography system such as an OCT
system and
the image of FIG. 7C is obtained with a video camera such as an alignment
camera as described
herein. The dimensions of coordinate system 650 can be aligned for each of the
measurement
systems of measurement system 150, and can define the measurement axis of the
eye.
[0200] The image of the eye may comprise one or more structures that can
be used to
identify one or more treatment axes of the eye and structures and optical
tissue surfaces of the
eye as described herein, which can be combined with data from one or more of
the tomography
or the tomography system as described herein to determine treatment axis and
alignment of the
eye, for example. The structure of the image of the eye may comprise an image
of a marker of
the eye such as an ink dot 43ID placed by a health care provider such as a
physician or an
ophthalmic technician, which can be used for alignment of the eye such as
cyclo torsional
alignment of the eye around one or more optical axes of the eye as described
herein. The ink dot
43ID may comprise a plurality of ink dots, for example a plurality of ink dots
on a plurality of
opposing sides of the pupil. The structure of the image of the eye may
comprise images of blood
vessels 43BV that can be used for alignment of the eye, such as cyclo
torsional alignment of the
eye around one or more axes of the eye as described herein, for example. The
structure image of
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the eye may comprise structure of the iris that can be used for alignment of
the eye, such as
torsional alignment of the eye around one or more axes of the eye as described
herein, for
example.
[0201] The eye may comprise one or more treatment axes, such as treatment
axis 43TA,
and the location of treatment axis 43TA can depend upon the layer and tissue
structure of the eye
being treated, for example the lens or the cornea. The treatment axis 43TA may
comprise an
axis of an aberration of the eye such as an astigmatism of the eye or a higher
order aberration of
the eye such as coma or trefoil of the eye, for example. The treatment axis
43A can be identified
by the system user such as a physician, and can be defined to have a center
corresponding to one
or more of the optical axes as described herein such as one or more of the
vertex of the cornea,
the line of sight of the eye, the visual axis of the eye, or the visual axis
of the eye extending from
the anterior node of the eye. Alternatively or in combination, the axis
identified by the user can
be different for the type of treatment of the eye. For example, with arcuate
incisions such as
limbal relaxing incisions, the treatment axis may comprise the line of sight
or the vertex of the
cornea, or other axis as described herein. With an intraocular lens to be
placed, the treatment
axis may comprise a center of the real pupil, a center of the line of sight, a
center of the visual
axis extending from an anterior node of the eye, or other axis as described
herein, for example.
Merely by way of example in accordance with embodiments, the treatment axis
43A is shown
with reference to the line of sight 43L0S corresponding to the center of the
entrance pupil when
the patient fixates on light 119 and the eye is viewed with the video camera
as described herein,
for example.
[0202] The eye may comprise one or more fiducial marker axes or meridians
43FMA,
and the location of fiducial marker axis or meridian 43FM can depend upon the
layer and tissue
structure of the eye being treated, for example the lens or the cornea. The
fiducial marker axis
43FMA is preferably an axis or meridian of an aberration of the eye such as an
astigmatism of
the eye or a higher order aberration of the eye such as coma or trefoil of the
eye, for example,
and may be the same or different from the treatment axis 43TA. The fiducial
marker axis
43FMA can be identified by the system user such as a physician, and can be
defined to have a
center corresponding to one or more of the optical axes as described herein
such as one or more
of the vertex of the cornea, the line of sight of the eye, the visual axis of
the eye, or the visual
axis of the eye extending from the anterior node of the eye. With an
intraocular lens to be
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placed, the fiducial marker axis may comprise a center of the real pupil, a
center of the line of
sight, a center of the visual axis extending from an anterior node of the eye,
or other axis as
described herein, for example.
[0203] FIG. 7F shows rotation and translation of the measurement
coordinate reference
system 650 relative to the eye coordinate reference system 150 when the eye
has contacted the
patient interface, in which the rotation and translation of the measurement
system 650 prior to
contact with the patient interface corresponds to rotation and translation of
the eye relative to the
coordinate system 150 when the patient interface contacts the eye. The
rotation and translation
of one or more of the tissue structures of the eye determined with the natural
pupil and vision of
the eye can be correspondingly rotated and translated and provided on a
display for the physician
to determine the treatment of the eye. The locations and orientations of the
tissue structures of
the eye determined with measurements of the eye prior to coupling with the
patient interface can
be mapped from the coordinate system 650 to the coordinate 150 and shown on
the display with
the image of the eye coupled to patient interface. This allows the user to
determine the treatment
with the coordinate reference 150 with the eye contacting the patient
interface, while showing
the locations of the structures of the eye from used for natural vision from
the coordinate
reference frame 650 on the patient interface.
[0204] FIG. 7G shows an optical schematic of the eye as in FIGS. 7A and
7B, with
structures of eye including the cardinal points of the eye and axes of the eye
useful for vision. In
many embodiments, one or more structures of the optical schematic of the eye
are projected onto
the display and aligned with the image of the eye shown on the display in
order for the user to
plan the incisions and surgical treatment of the eye.
[0205] In many embodiments, one or more of the tissue structures of each
of images 7A
to 7G can be shown on the display to the user for planning the locations of
incisions as described
herein, such as the location of the nodal points of the eye along the optical
axis of the eye, the
line of sight of the eye, the vertex of the cornea, and the visual axis
extending from the anterior
nodal point of the eye. For example, the one or more structures of the optical
schematic of the
eye determined from measurements prior to contacting the eye can be shown on
the display
aligned with images of the eye obtained when the patient interface has
contacted the eye, in order
for the surgeon to determine the locations of incisions in alignment with the
one or more
structures of the eye determined from measurements obtained prior to contact
with the patient
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interface when the patient interface contacts the eye. Alternatively or in
combination, the one or
more optical structures of the eye shown on the display can be determined in
response to
measurements obtained when the patient interface contacts the eye, for example
for comparison
with locations of the one or optical structures determined from measurements
obtained prior to
the patient interface contacting the eye.
[0206] The average axial length of the adult human eye is about 24 mm.
Since the full
range imaging depth of the OCT measurements are only about 5 mm to 8 mm, then
OCT
scanning of the invention may provide for OCT scans at different depths of the
eye that can be
combined together to determine various biometry measurements, including the
axial length, to
determine corneal shape information and to determine lens shape information.
The OCT
measurements of the present invention preferably includes OCT imaging at
various depths of the
patient's eye for imaging 1) at least a portion of the retina, 2) at least a
portion of the anterior
portion of the eye, including at least a portion of the cornea (anterior and
posterior), iris, and lens
(anterior and posterior) , and 3) performing axial eye length measurements.
[0207] In many embodiments, the controller is coupled to an Optical
Coherence
Tomography (OCT) subsystem of the ranging subsystem. The OCT subsystem is
preferably
configured to sequentially scan the eye in a plurality of OCT scan patterns,
each scan pattern
being at a different axial depth of a patient's eye as shown graphically in
FIG. 9A. The plurality
of scan patterns comprise an anterior segment OCT scan pattern in a region at
or near a location
of a cornea, preferably a region including the anterior surface of the cornea
and the posterior
surface of the cornea, shown as region "A" in Figure 9A. The plurality of
scans may be in an
axial or lateral directions. Scans in region "A" may for instance be selected
to provide corneal
surface information regarding the axial position of the anterior surface of
the cornea, the shape of
the anterior surface of the cornea, the axial position of the posterior
surface of the cornea, and the
shape of the posterior surface of the cornea. The plurality of scan patterns
preferably also
comprise a lenticular OCT scan pattern at or near a location of a lens,
preferably in a region
including the anterior surface of the lens and the posterior portion of the
lens, shown as region
"B" in FIG. 9A. The plurality of scans may be in an axial or lateral
directions. Scans in region
"B" may for instance be selected to provide lens surface information regarding
the axial position
of the anterior surface of the lens, the shape of the anterior surface of the
lens, the axial position
of the posterior surface of the lens and the shape of the posterior surface of
the lens, and the
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equator of the lens. The plurality of OCT scan patters further preferably
comprises a retinal
OCT scan pattern at or near a location of a retina, which may include a
portion of the posterior
pole of the axially anterior to the retina, as shown in region "C" in FIG. 9A.
The plurality of
imaging scan patterns preferably comprises an OCT scan pattern suitable to
measure a plurality
of an anterior corneal surface, a corneal pachymetry, a central corneal
thickness, and an anterior
chamber depth of a patient's eye. The plurality of imaging scan patterns
preferably also
comprises a lenticular OCT scan segment scan pattern suitable to measure a
plurality of a lens
thickness, an anterior lens surface, and a posterior lens surface. The
plurality of imaging scan
patterns comprises a retinal OCT segment scan pattern suitable to measure at
least the axial
length.
[0208] In many embodiments, the laser surgery system comprises a memory
operable to
store data acquired from each of the corneal topography subsystem and the
Optical Coherence
Tomography subsystem, wherein the stored data includes a plurality of ocular
biometry
information, anterior corneal surface information, posterior corneal surface
information, anterior
lens surface information, and posterior lens surface information, and lens
position information.
The ocular biometry information preferably comprises a plurality of a central
corneal thickness
(CCT), an anterior chamber depth (ACD), a lens thickness (LT), and an axial
length (AXL) as
shown in FIG. 9A. In many embodiments, the ocular biometry information
preferably includes
the lens thickness.
[0209] In many embodiments, a model of the eye is constructed based on
all or some of
the stored data, including the data of each of the corneal topography
subsystem and the Optical
Coherence Tomography subsystem. The data used to construct the model
preferably includes a
plurality of ocular biometry information, anterior corneal surface
information, posterior corneal
surface information, anterior lens surface information, and posterior lens
surface information,
and lens position information. The ocular biometry information used to
construct the model
preferably comprises a plurality of a central corneal thickness (CCT), an
anterior chamber depth
(ACD), a lens thickness (LT), and an axial length (AXL) as shown in FIG. 9A.
The model of
the eye may be performed with the human lens intact in the subject eye. The
data, including the
ocular biometry information, may be modified based on a measured index of
refraction of one or
more ocular tissues as discussed herein. In many embodiments, the model is
performed using
ray tracing.
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[0210] A method of obtaining OCT information at various optical lengths
of the eye is
shown, for instance, in FIG. 9B. A step 810 comprises aligning the eye with
the OCT
subsystem. A step 820 comprises adjusting the reference arm to set OCT scan
location at or
near cornea, and performing an OCT Scan with the OCT Subsystem. A step 830
comprises
adjusting the reference arm to set the OCT location at a location at or near
the lens anterior and
performing an OCT Scan with the OCT Subsystem. An optional step 840 comprises
adjusting
the reference arm to set the OCT location at a location at or near the lens
posterior and
performing an OCT Scan with the OCT Subsystem. A step 850 comprises adjusting
the
reference arm to set the OCT location at a location at or near the retina and
performing an OCT
Scan with the OCT Subsystem.
[0211] The laser surgery system according to the present invention
preferably includes a
refractive index correcting subsystem. The refractive index correcting
subsystem general refers
to that portion of the laser surgery system 2 which operate cooperatively to
identify and measure
the index of refraction of one or more of the ophthalmic tissues. The selected
tissues may be one
or more selected for the group consisting of the cornea, the aqueous humor,
the lens and the
vitreous humor. The measured indexes of refraction for the selected tissue can
be used to more
accurately determine biometry and surface information and thus improve the
modeling of the
patient's eye, by for example, ray tracing.
[0212] In many embodiments, a physical distance can be obtained by
dividing the optical
path length by the index of refraction of the material through which the light
beam passes. Prior
to measurement of an actual index of refraction for a selected tissue, a group
refractive index
may be used and can take into account the group velocity of the light with a
center wavelength
and bandwidth and dispersion characteristics of the beam train. When the beam
has passed
through more than one material, the physical distance can be determined based
on the optical
path length through each material, for example. The tissue structures of the
eye and
corresponding index of refraction can be identified and the physical locations
of the tissue
structures along the optical path determined based on the optical path length
and the indices of
refraction. When the optical path length extends along more than one tissue,
the optical path
length for each tissue can be determined and divided by the corresponding
index of refraction so
as to determine the physical distance through each tissue, and the distances
along the optical path
can be combined, for example with addition, so as to determine the physical
location of a tissue
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structure along the optical path length. Additionally, optical train
characteristics may be taken
into account. As the OCT beam is scanned in the X and Y directions and
departure from the
telecentric condition occurs due to the axial location of the galvo mirrors, a
distortion of the
optical path length is realized. This is commonly known as fan error and can
be corrected for
either through modeling or measurement.
[0213] As one or more optical components and light sources as described
herein may
have different path lengths, wavelengths, and spectral bandwidths, in many
embodiments the
group index of refraction used depends on the material and the wavelength and
spectral
bandwidth of the light beam. In many embodiments, the index of refraction
along the optical
path may change with material. For example, the saline solution may comprise a
first index of
refraction, the cornea may comprise a second index of refraction, the anterior
chamber of the eye
may comprise a third index of refraction, and the eye may comprise gradient
index lens having a
plurality of indices of refraction. While optical path length through these
materials is governed
by the group index of refraction, refraction or bending of the beam is
governed by the phase
index of the material. Both the phase and group index can be taken into
account to accurately
determine the X, Y, and Z location of a structure. While the index of
refraction of tissue such as
eye 43 can vary with wavelength as described herein, approximate values
include: aqueous
humor 1.33; cornea 1.38; vitreous humor 1.34; and lens 1.36 to 1.41, in which
the index of the
lens can differ for the capsule, the cortex and the nucleus, for example. The
phase index of
refraction of water and saline can be about 1.325 for the ultrafast laser at
1030 nm and about
1.328 for the OCT system at 830 mm. The group refractive index of 1.339
differs on the order of
1% for the OCT beam wavelength and spectral bandwidth. Many embodiments herein
provide
methods for determining the indices of refraction and group indices of
refraction of the tissues of
the eye for the wavelengths of the measurement and treatment systems as
described herein. The
index of refraction of the other components of the system can be readily
determined by a person
of ordinary skill in the art based on the teachings described herein.
[0214] FIG. 10A shows light from shared optics 50 as directed by ranging
subsystem 46
focused onto the lens LE of the eye 43. The beam 500 from shared optics 50 can
be focused
onto a target focal point 510 within the lens LE. The beam 500, however, may
instead be
focused onto a different target focal point within other anatomical locations
in the eye 43 such as
a tear film, a cornea CO, an aqueous humor AH, an anterior lens capsule, a
lens cortex, an
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anterior portion of the lens cortex, a posterior portion of the lens cortex, a
lens nucleus, a
posterior lens capsule, or a vitreous humor VH. FIG. 10A also shows the iris
IR and the ciliary
muscles CI of the eye 43.
[0215] According to many embodiments, the ranging subsystem 46 of the
system 2 can
be used to determine the indices of refraction of the tissues of the eye 43.
As shown in FIG.
10A, the eye 43 is coupled with the patient interface 52 which comprises a
suitable liquid 52 a
(e.g., a sterile buffered saline solution (BSS) such as Alcon BSS (Alcon Part
Number 351-
55005-1) or equivalent) is disposed between and in contact with the patient
interface lens
posterior surface and the patient's cornea CO and forms part of a transmission
path between the
shared optics 50 and the patient's eye 43.
[0216] In many embodiments, the ranging subsystem 46 determines the
location of the
target focal point 510 in response to predetermined indices of refraction of
the anatomical
structures of the eye. One or more of the ranging subsystem 46 or the shared
optics 50 may
accounts for the indices of refraction of the structures between the shared
optics 50 and the target
focal point 510 to determine the configuration of the shared optics 50 to
properly locate and
focus the beam 500 onto the target focal point 510. For example, one or more
of the XY-scan
and Z-scan mechanisms of the shared optics 50 may be adjusted in response to
the indices of
refraction of the structures between the shared optics 60 and the target focal
point 510. As
shown in FIG. 10A, to focus the beam 500 onto the focal point 510 within the
lens LE, the
anatomical structures and materials that need to be taken into account include
the suitable liquid
52 a, the cornea CO, the aqueous humor AH, and the lens LE. The index of
refraction of the
suitable liquid 52 a may be known or can be predetermined. The indices of
refraction of the
cornea CO and the aqueous humor AH typically do not vary significantly across
individuals.
The indices of refraction of the lens LE, however, can vary significantly
across individuals.
Further, the indices of refraction may vary even within the lens LE. The
ranging subsystem 46
may first assume an index of refraction for the lens LE, for example, in
response to an average
lens index of refraction for a patient population. As shown in FIG. 10A, the
target focal point
510 may actually be different than the actual focal point 520. Thus, the
indices of refraction
through the lens LE can be determined and the ranging subsystem 46 may further
be configured
to take into account the determined indices of refraction. As described
herein, the positional
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differences between the target focal point 510 and the actual focal point 520
can be used to
determine the index of refraction of at least a portion of the lens LE.
[0217] FIG. 10B show various target focal points 510A, 510B, 510C, 510D,
510E, 510F,
510G, 510H, 5101, 510J, 510K, and 510L through the anatomical structures of
the eye EY for
determining the indices of refraction of the various anatomical structures. As
described here, one
or more of the ranging subsystem 46 and the shared optics 50 may be used to
determine the
positional differences between each of these target focal points and their
corresponding actual
focal points to determine the index of refraction for the corresponding tissue
structure of the eye.
As shown in FIG. 5B, the target focal points 510A and 510B may be within the
cornea CO; the
target focal points 510C and 510D may be within or at the edge of the aqueous
humor AH, the
target focal points 510E, 510F, and 510G may be within or at the edge of the
lens LE, and the
target focal points 510H, 5101, 510J, 510K, and 510L may be within the
vitreous humor VH.
[0218] FIG. 10B shows the target focal points being varied along the
vertical or Z-axis
156, for example by adjusting the shared optics 50. As shown in FIG. 5C,
target focal points 511
may also be varied along the horizontal axes such as X-axis 152 and Y-axis
154. For example,
by varying target focal points up to three dimensionally, i.e., across one or
more of the X-axis
152, Y-axis 154, or Z-axis 156, up to a three-dimensional gradient index of
refraction profile of
an anatomical structure of the eye EY such as the lens LE may be generated.
The laser eye
surgery system 2 described herein may apply the refractive index profile of
the lens LE to more
accurately place target focal points within the anatomical structures of the
eye which can lead to
more precise laser incisions.
[0219] FIG. 10D shows an exemplary refractive index profile 550 of the
eye 43. FIG.
10D shows the profile 550 as two-dimensional, i.e., comprises refractive index
information of
the lens LE in response to position in the Y-axis 154 and the Z-axis 156. The
profile 550 may in
many embodiments be three-dimensional and comprise refractive index
information of the lens
LE further in response to position in the X-axis 152. In at least some cases,
the indices of
refraction in the lens LE may vary within the lens LE. As shown in FIG. 10D,
the indices of
refraction in the first lens region 561, the second lens region 563, the third
lens region 565, the
fourth lens region 567, and the fifth lens region 569 may be different from
one another.
[0220] FIG. 11 shows a flow chart depicting a method 300 for determining
an index of
refraction of a target material according to many embodiments.
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[0221] In a step 410, light is focused to a first target location in a
target material. As
described herein, the focused light may comprise a beam 500, the first target
location may
comprise a target focal point 510, and the target material may comprise an
anatomical structure
of the eye 43 of a subject, such as the lens LE.
[0222] In a step 320, a distance between a surface of the target material
and the first
target location is determined. For example, the target material may comprise
the lens LE and the
surface of the target material may comprise the anterior surface of the lens
LE. A user may
direct the laser eye surgery system 2 to focus the beam 500 onto the target
focal point 510. In
response, the laser eye surgery system 2 may locate the target focal point 510
in response to
predetermined refractive index data as described herein.
[0223] In many embodiments, the assumed index of refraction used by the
laser eye
surgery system 2 to calculate the position of the target focal point 510 may
be referred to as
nassumed= The distance between the surface of the target material, e.g., the
anterior surface of the
lens LE, and the first target location, e.g., the target focal point 510, may
be referred to as
DCOMMAND= As described herein, the target focal point 510 may not be located
in the same
position as the actual focal point 520 due to refraction that the laser eye
surgery system 2 and the
ranging subsystem 46 may not account for. The distance between the surface of
the target
material, e.g., the anterior surface of the lens LE, and the actual focal
point 520 may be referred
to as DACTUAL . The actual index of refraction of the target material between
the surface, e.g., the
anterior surface of the lens LE, and the first target location, e.g., the
target focal point 510, may
be referred to as nactuai. In many embodiments, DACTUAL is related to DcommAND
in accordance
to the following equation: DACTUAL =DCOMMAND*(nactual/nassumed)=
[0224] In a step 330, a peak intensity location of the beam path is
located with an optical
interference signal. For example, the ranging subsystem 46 may measure the
intensity of the
beam path along an axis, such as a vertical or Z-axis, through the target
focal point 510 and may
determine the location of peak intensity along this path. This peak intensity
location may
correspond to the location of the actual focal point 520.
[0225] In a step 340, a distance between the surface of the target
material and the located
beam path peak intensity location is determined. In many embodiments, an
optical coherence
tomography (OCT) system is used to determine intensity through the beam path.
The distance
between the surface of the target material, e.g., the anterior surface of the
lens LE, and the
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located beam path peak intensity location may be referred to as DUCT. As light
may refract as it
propagates through the target material to be read by the OCT system, the OCT
system may
account for this refraction using an assumed index of refraction which may be
referred to as
nassumed= In many embodiments, DUCT is related to DAcTuAL , in accordance with
the following
equation: DOCT=DACTUAL *(nactual/nassumed)=
[0226] In a step 350, the index of refraction of the target material
between the target
material surface and the first target location is determined in response to
the determined
distances from the steps 320 and 340. In many embodiments, this index of
refraction comprises
the average index of refraction of the material between the target material
surface and the first
target location. To determine this index of refraction, the above
relationships or equations,
DACTUAL =DCOMMAND*(nactualinassumed) and DucT=DACTUAL *(nactual inassumed),
are applied.
DACTUAL is substituted for in the latter equation with the equivalent in the
former equations to
arrive at the equation: DocT=DcommAND*(nactua1/na55umed)2. nactual, or the
index of refraction of the
target material between the target material surface and the first target
location, can then be
calculated for using the rearranged equation:
Ilactual=rlassumed*SCIrt(DucT/DcummAND). The
determined index of refraction can be mapped to the area of the lens of the
eye.
[0227] In a step 360, the above steps 310 to 350 can be repeated for a
second target
location. The second target location may be in the same target material or a
different target
material. Also, instead of using the surface of the target material as the
reference point for steps
320 and 340, the first target location may be used as the reference point for
steps 320 and 340.
As disclosed herein, the indices of refraction for a plurality of locations
within a target material
such as the lens LE can be measured to determine a refractive index profile of
the target material,
for example as shown in FIG. 5D.
[0228] One skilled in the art will appreciate that the above steps of the
method 300 are by
way of example. The ordering of the steps may be varied and one or more steps
may be
modified, added, or omitted without departing from the scope of the
disclosure. A processor
system of the laser eye surgery system 2 may comprise tangible medium
embodying instructions
for performing one or more steps of the method 300. Following the method 300,
one or more of
various surgical procedures may be performed on the eye. Such eye surgery
procedures may
include cataract surgery in response to the measured index or indices of
refraction, retinal
surgery in response to the measured index or indices of refraction, vitreo-
retinal surgery in
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response to the measured index or indices of refraction, glaucoma surgery in
response to the
measured index or indices of refraction, refractive eye surgery in response to
the measured index
or indices of refraction, corneal surgery in response to the measured index or
indices of
refraction, and many other eye surgery procedures in response to the measured
index or indices
of refraction.
[0229] An example of refractive index measurement of an anatomical
structure of the eye
is now provided.
[0230] FIG. 12 shows an intensity graph 700 of various beam paths through
various
anatomical structures of the eye for various desired focal points. The beam
path intensity
profiles may be measured from the ranging subsystem 46 which may comprise an
optical
coherence tomography (OCT) system. The intensity graph 700 shows a first beam
path intensity
profile 701, a second beam path intensity profile 702, a third beam path
intensity profile 703, a
fourth beam path intensity profile 704, a fifth beam path intensity profile
705, a sixth beam path
intensity profile 706, a seventh beam path intensity profile 707, an eight
beam path intensity
profile 708, a ninth beam path intensity profile 709, and a tenth beam path
intensity profile 710.
Each beam path intensity profile may correspond to a target focal point in the
lens of an eye,
with the higher numbered beam path profiles corresponding to deeper target
focal points in the
lens of the eye. For instance, the target focal point corresponding to the
tenth beam profile 710
may be deeper than the target focal point corresponding to the ninth beam
profile 709, which
may be deeper than the target focal point corresponding to the eight beam
profile 708, which
may be deeper than the target focal point corresponding to the seventh beam
profile 707, which
may be deeper than the target focal point corresponding to the sixth beam
profile 706, which
may be deeper than the target focal point corresponding to the fifth beam
profile 705, which may
be deeper than the target focal point corresponding to the fourth beam profile
704, which may be
deeper than the target focal point corresponding to the third beam profile
703, which may be
deeper than the target focal point corresponding to the second beam profile
702, which may be
deeper than the target focal point corresponding to the first beam profile
701. Each of these
beam path intensity profiles may comprise a first high intensity band 750 and
a second high
intensity band 755. In many embodiments, the first and second high intensity
bands 750, 755
comprise reflections from surfaces of one or more anatomical structures of the
eye. For
example, the first high intensity band 750 may comprise a reflection from the
anterior surface of
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the cornea and the second high intensity band 755 may comprise a reflection
from the posterior
surface of the cornea.
[0231] The first beam path intensity profile 701 may comprise a peak
intensity band 711
which may correspond to the focal point of the beam focused onto a first
target focal point. The
second beam path intensity profile 702 may comprise a peak intensity band 712
which may
correspond to the focal point of the beam focused onto a second target focal
point. The third
beam path intensity profile 703 may comprise a peak intensity band 713 which
may correspond
to the focal point of the beam focused onto a third target focal point. The
fourth beam path
intensity profile 704 may comprise a peak intensity band 714 which may
correspond to the focal
point of the beam focused onto a fourth target focal point. The fifth beam
path intensity profile
705 may comprise a peak intensity band 715 which may correspond to the focal
point of the
beam focused onto a fifth target focal point. The sixth beam path intensity
profile 706 may
comprise a peak intensity band 716 which may correspond to the focal point of
the beam focused
onto a sixth target focal point. The seventh beam path intensity profile 707
may comprise a peak
intensity band 717 which may correspond to the focal point of the beam focused
onto a seventh
target focal point. The eight beam path intensity profile 708 may comprise a
peak intensity band
718 which may correspond to the focal point of the beam focused onto an eighth
target focal
point. The ninth beam path intensity profile 709 may comprise a peak intensity
band (not
shown) which may correspond to the focal point of the beam focused onto a
ninth target focal
point. The tenth beam path intensity profile 710 may comprise a peak intensity
band which may
correspond to the focal point of the beam focused onto a tenth target focal
point.
[0232] In the following example, the average index of refraction in the
lens LE of the eye
between two points can be calculated in response to the intensity graph 700.
The peak intensity
band 712 of the second beam path intensity profile 702 is located at a
distance of 8.8 mm. The
peak intensity band 718 of the eight beam profile 708 is located at a distance
of 12.25 mm. The
distance or difference between the two peak intensity bands 712 and 718 is
therefore 3.45 mm.
As described herein, this distance of 3.45 mm is regarded as DUCT. The
distance between the
target focal point for the second beam path intensity profile 702 and the
target focal point for the
eight beam path intensity profile 708, or DcummAND, is 3 mm. That is, where
the laser eye
surgery system 2 is commanded to vary two focal points by 3 mm, the ranging
subsystem 46 of
the laser eye surgery system 2 detects the distance as 3.45 mm. As described
herein, the index of
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refraction of the lens of the eye may be assumed. In this example, the assumed
index of
refraction, or nassumed, is considered to be 1.3388. As described herein, the
actual average index
of refraction can be calculated in response to the aforementioned variables
using the equation:
nactual=nassumeesqrt(Docr/DcommAND). In this example, nactual, or the average
index of refraction
between the target focal points for the second beam path intensity profile 702
and the third beam
path intensity profile 708, would therefore be 1.3388*sqrt(3.45/3) or 1.4357.
As described
herein, the indices of refraction of the lens LE of the eye and other
structures of the eye may
vary, and by generating a refractive index profile of the lens LE of the eye
and other structures of
the eye, a laser eye surgery system 2 can more accurately place laser beam
focal points within
the eye such as to more accurately place incisions.
[0233] The laser eye surgery system 2 and the optical measurements
obtained therewith
may be used pre-operatively, i.e. before a cataract surgery or other surgical
procedure, for, e.g.,
eye biometry and other measurements, diagnostics and surgical planning.
Surgical planning may
include one or more predictive models. In the one or more predictive models,
one or more
characteristics of the postoperative condition of the patient's eye or vision
is modeled based on
one or more selected from the group consisting of pre-operative measurements
obtained from the
laser eye surgery system 2, a contemplated surgical intervention, and on or
more algorithms or
models stored in the memory of the laser eye surgery system 2 and executed by
the processor.
The contemplated surgical intervention may include the selection of an IOL for
placement, the
selection of an IOL characteristic, the nature or type of incision to be used
during surgery (e.g.,
relaxation incision), or one or more post-operative vision characteristics
requested by the patient.
[0234] The laser eye surgery system 2 and the optical measurements
obtained therewith
may be used intra-operatively, i.e., during a cataract surgery or other
surgical procedure, for, e.g.,
intraoperative eye diagnostics, determining IOL position and/or orientation,
surgical planning,
and control/or of a laser surgical system. For instance, in the case of laser
cataract surgical
procedure, any measurement data obtained preoperatively by the optical
measurement instrument
may be transferred to a memory associated with a cataract laser surgical
system for use before,
during or after either the placement of a capsulotomy, fragmentation or a
patient's lens or IOL
position and/or orientation during the cataract surgery. In this regard,
conditions measured
during the surgical procedure may be compared to a predicted condition of the
patient's eye
based on pre-operative measurements, and a difference between the predicted
condition and the
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actual measured condition may be used to undertake additional or corrective
actions during the
cataract surgery or other surgical procedure. The corrective procedure may
also be merely based
on intraoperative measurements so that the actual measured condition dictates
the action that is
needed to provide the desired outcome.
[0235] The laser eye surgery system 2 and the optical measurements
obtained therewith
may be used postoperatively, i.e., after a cataract surgery or other surgical
procedure, for, e.g.,
post-operative measurement, postoperative eye diagnostics, postoperative IOL
position and/or
orientation determinations, and corrective treatment planning if necessary.
The postoperative
testing may occur sufficiently after the surgery that the patient's eye has
had sufficient time to
heal and the patient's vision has achieved a stable, postsurgical state. A
postoperative condition
may be compared to one or more predicted condition performed pre-operatively,
and a difference
between the preoperatively predicted condition and the postoperatively
measured condition may
be used to plan additional or corrective actions during the cataract surgery
or other surgical
procedure. The corrective procedure may also be merely based on intraoperative
measurements
so that the actual measured condition dictates the action that is needed to
provide the desired
outcome.
[0236] The laser eye surgery system 2 preferably stores all the biometric
data and
postoperative information in an embedded database, so that the data contained
in this database
can be used to further optimize or generate new algorithms to improve future
patient's outcomes.
In certain embodiments, these algorithms are related to optimize actual lens
position prediction,
surgically induced astigmatism, IOL constants or personalized regressions to
account for corneal
spherical aberration in IOL power calculations for post-LASIK eyes.
[0237] The laser eye surgery system 2, including the corneal topography
subsystem, the
OCT subsystem and the ranging subsystem, utilizing a suitable operating
sequence as disclosed
herein, is operable to measure one, more than one or all of the following:
ocular biometry
information, anterior corneal surface information, posterior corneal surface
information, anterior
lens surface information, posterior lens surface information, lens thickness
information, and lens
position information. In some embodiments, the ocular biometry information may
include a
plurality of central corneal thicknesses (CCT), an anterior chamber depth
(ACT), a lens thickness
(LT), and an axial length (AL), any or all of which may be based on the
measured index or
refraction as described herein. This measurement data may be stored in memory
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with controller 60. The plurality of characteristics may be measured
intraoperatively, and where
appropriate, preoperatively, and postoperatively.
[0238] In some embodiments, memory 62 associated with controller 60 may
store
intraocular lens (IOL) model data for a plurality of IOL models, each of the
IOL models having
associated with it a plurality of predetermined parameters selected from the
group consisting of
dioptic power, refractive index and dispersion, asphericity, toricity,
echellete features, haptic
angulation and lens filter. The IOL data may be used by one or more processors
of laser eye
surgery system 2, in conjunction with measurement data of a subject's eye
obtained by laser eye
surgery system 2, for cataract diagnostics or cataract treatment planning,
which may include
specifying and/or selecting a particular IOL for a subject's eye. For example,
one or more
processors of laser eye surgery system 2 may execute an algorithm which
includes: accessing the
plurality of IOL models stored in, and for each of the IOL models: (1)
modeling the subject's eye
with an intraocular lens corresponding to the IOL model and the measured
characteristics of the
subject's eye; (2) simulating the subject's eye based on the plurality of IOL
predetermined
parameters and the predicted IOL position; (3) performing one of a ray tracing
and a power
calculation based on said model of the subject's eye; and (4) selecting an IOL
for the subject's
eye from the plurality of IOL models corresponding to the optimized IOL based
on a
predetermined criteria and the measured characteristics of the patient's
obtained by the laser
surgery system 2..
[0239] In some embodiments, one or more processors of laser eye surgery
system 2 may
execute an algorithm comprising: determining a desired postoperative condition
of the subject's
eye; empirically calculating a post-operative condition of the eye based at
least partially on the
measured eye characteristics; and predictively estimating, in accordance with
an output of said
empirically calculating and the eye characteristics, at least one parameter of
an intraocular lens
for implantation into the subject's eye to obtain the desired postoperative
condition.
[0240] In many embodiments, the eye imaging and measurement system
further
comprises a memory operable to store Intraocular Lens ("IOU') Data, the IOL
data including a
plurality of dioptic power, anterior and posterior radius, IOL thickness,
refractive index and
dispersion, asphericity, toricity, echelette features, haptic angulation and
lens filter.
[0241] In many embodiments, the eye imaging and measurement system
further
comprises a memory operable to store intraocular lens ("IOU') model data for a
plurality of IOL
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models, IOL model having associated with a plurality of predetermined
parameters selected from
the group consisting of dioptic power, anterior and posterior radius, IOL
thickness, refractive
index and dispersion, asphericity, toricity, echelette features, haptic
angulation and lens filter.
[0242] An improved system for selecting an intraocular lens (IOL) for
implantation,
comprises: a memory operable to store data acquired from each of the corneal
topography
subsystem, a ranging subsystem and the Optical Coherence Tomography subsystem,
wherein the
stored data includes a plurality of ocular biometry information, anterior
corneal surface
information, posterior corneal surface information, anterior lens surface
information, and
posterior lens surface information, lens thickness information, and lens
position information; the
memory further operable to store intraocular lens ("IOU') model data for a
plurality of IOL
models, IOL model having associated with it a plurality of predetermined
parameters selected
from the group consisting of dioptic power, anterior and posterior radius, IOL
thickness,
refractive index and dispersion, asphericity, toricity, echelette features,
haptic angulation and
lens filter; and a processor coupled to the memory, the processor deriving the
treatment of the
eye of the patient applying, for each of the plurality of identified IOL
Model, to: (1) predict a
position of one of the identified IOL Models when implanted in the subject
eye, based on the
plurality of characteristics; (2) simulate the subject eye based on the
plurality of IOL
predetermined parameters and the predicted IOL position; (3) perform one or
more of ray
tracing and an IOL spherical equivalent (SE) and cylinder (C) power
calculation, as well as
optionally, to determine the optimum IOL orientation based on said eye model;
and (4) propose
one IOL power for one or more IOL models from the plurality of IOLs
corresponding to the
optimized IOL(s) based on predetermined criteria; and (5) show the simulated
optical quality
and/or visual performance provided by each of the proposed IOL models for
distance and/or for
any other vergence and/or field angle.
[0243] A method of selecting an intraocular lens (IOL) to be implanted in
a subject's eye,
comprising: measuring a plurality of eye characteristics comprising ocular
biometry
information obtained via the laser surgery system 2, anterior corneal surface
information,
posterior corneal surface information, anterior lens surface information, and
posterior lens
surface information, lens thickness information and lens position information;
and for each of
Intraocular Lens ("IOU') model having associated with it a plurality of
predetermined
parameters selected from the group consisting of dioptic power, refractive
index and dispersion,
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anterior and posterior radius, IOL thickness, asphericity, toricity, echelette
design, haptic
angulation and lens filter: (1) modeling the subject eye with the intraocular
lens; (2) simulating
the subject eye based on the plurality of IOL predetermined parameters and the
predicted IOL
position; (3) performing a ray tracing and an IOL spherical equivalent (SE)
and cylinder (C)
power calculation, as well as determine the optimum IOL orientation based on
said eye model;
and (4) proposing one IOL power for one or more IOL models from the plurality
of IOLs
corresponding to the optimized IOL(s) based on predetermined criteria; and
optionally (5) show
the simulated optical quality and/or visual performance provided by each of
the proposed IOL
models for distance and/or for any other vergence and/or field angle.
[0244] A tangible computer-readable storage device storing computer
instructions which,
when read by a computer, cause the computer to perform a method comprising:
receiving a
plurality of eye characteristics comprising ocular biometry information,
anterior corneal surface
information, posterior corneal surface information, anterior lens surface
information, and
posterior lens surface information, lens thickness information and lens
position information; for
each of Intraocular Lens ("IOU') model having associated with it a plurality
of predetermined
parameters selected from the group consisting of dioptic power, refractive
index and dispersion,
anterior and posterior radius, IOL thickness, asphericity, toricity, echelette
design, haptic
angulation and lens filter: (1) simulating a geometry of the subject eye with
each of the plurality
of intraocular lenses (IOL) implanted, in accordance with the plurality of eye
characteristics; (2)
performing a ray tracing and an IOL spherical equivalent (SE) and cylinder (C)
power
calculation, as well as optionally determining the optimum IOL orientation
based on said eye
model; (3) proposing one IOL power for one or more IOL models from the
plurality of IOLs
corresponding to the optimized IOL(s) based on predetermined criteria; and
optionally (4)
showing the simulated optical quality and/or visual performance provided by
each of the
proposed IOL models for distance and/or for any other vergence and/or field
angle.
[0245] A method of predicting the intraocular lens position comprising:
determining a
plurality of eye characteristics before cataract surgery, comprising ocular
biometry information,
anterior corneal surface information, posterior corneal surface information,
anterior lens surface
information, and posterior lens surface information, lens thickness
information and lens position
information; determining a plurality of eye characteristics after cataract
surgery, comprising
ocular biometry information, anterior corneal surface information, posterior
corneal surface
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information, anterior IOL surface information, and posterior IOL surface
information, IOL tilt
information, and IOL position information; calculating or measuring, based on
a mathematical
relationship, a distance from the apex or from the retina to a plane of the
intraocular lens after an
ocular surgical procedure; calculating an optical power of the intraocular
lens suitable for
providing a predetermined refractive outcome; wherein a mathematical
relationship is found
between the preoperative and postoperative eye characteristics that accurately
predict the
measured distance from the apex or from the retina to the plane where the
intraocular lens is. In
a certain embodiment, the method herein described to predict the IOL position
may depend on
the IOL model and/or patient's biometric configurations.
[0246] An improved system for planning a refractive treatment of an eye
of a patient, the
system comprising: a memory operable to store eye measurement data comprising
ocular
biometry information, anterior corneal surface information, posterior corneal
surface
information, anterior lens surface information, and posterior lens surface
information, and lens
position information; a processor coupled to the memory, the processor
deriving the treatment of
the eye of the patient applying an effective treatment transfer function,
wherein the effective
treatment transfer function is derived from, for each of a plurality of prior
eye treatments, a
correlation between a pre-treatment vector characterizing the eye measurement
data before
treatment, and a post-treatment vector characterizing post-treatment eye
measurement data of the
associated eye; an output coupled to the processor so as to transmit the
treatment to facilitate
improving refraction and/or higher order aberration and/or optical quality of
the eye of the
patient for one or more multiple vergences and/or field angles. The processor
preferably
comprises tangible media embodying machine readable instructions for
implementing the
derivation of the treatment.
[0247] An improved method for planning a refractive treatment of an eye
of a patient, the
system comprises: measuring a plurality of ocular biometry information,
anterior corneal surface
information, posterior corneal surface information, anterior lens surface
information, and
posterior lens surface information, lens thickness information and lens
position information.
[0248] A method of customizing at least one parameter of an intraocular
lens,
comprising: measuring a plurality of eye characteristics comprising ocular
biometry
information, anterior corneal surface information, posterior corneal surface
information, anterior
lens surface information, and posterior lens surface information, and lens
position information;
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determining a desired postoperative condition of the eye; empirically
calculating a post-operative
condition of the eye based at least partially on the measured eye
characteristics; and predictively
estimating, in accordance with an output of said empirically calculating and
the eye
characteristics, the at least one parameter of the intraocular lens to obtain
the desired
postoperative condition.
[0249] In some embodiments, the system further comprises a processor
configured to
execute an algorithm. The algorithm comprises, for each of the IOL models: (1)
modeling the
subject's eye with an intraocular lens corresponding to the IOL model and the
measured
characteristics of the subject's eye; (2) simulating the subject's eye based
on the plurality of
IOL predetermined parameters and the predicted IOL position; (3)
performing one of a ray
tracing and a power calculation based on said model of the subject's eye; and
(4) selecting
an IOL from the plurality of IOL models corresponding to the optimized IOL
based on a
predetermined criteria.
[0250] Unless the context clearly requires otherwise, throughout the
description and the
claims, the words "comprise," "comprising," and the like are to be construed
in an inclusive
sense as opposed to an exclusive or exhaustive sense; that is to say, in a
sense of "including, but
not limited to." Words using the singular or plural number also include the
plural or singular
number respectively. Additionally, the words "herein," "hereunder," "above,"
"below," and
words of similar import refer to this application as a whole and not to any
particular portions of
this application. When the word "or" is used in reference to a list of two or
more items, that word
covers all of the following interpretations of the word: any of the items in
the list, all of the items
in the list and any combination of the items in the list.
[0251] Although certain presently preferred implementations of the
invention have been
specifically described herein, it will be apparent to those skilled in the art
that the embodiments
are provided by way of example only numerous variations, changes, and
substitutions will be
apparent to those skilled in the art without departing from the scope of the
present disclosure. It
should be understood that various alternatives to the embodiments of the
present disclosure
described herein may be employed without departing from the scope of the
present invention.
Therefore, the scope of the present invention shall be defined solely by the
scope of the
appended claims and the equivalents thereof.
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[0252] The
foregoing description, for purpose of explanation, has been described with
reference to specific examples. However, the illustrative discussions above
are not intended to be
exhaustive or to limit the invention to the precise forms disclosed. Many
modifications and
variations are possible in view of the above teachings. The examples were
chosen and described
in order to best explain the principles of the invention and its practical
applications, to thereby
enable others skilled in the art to best utilize the invention and various
examples with various
modifications as are suited to the particular use contemplated.
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