Note: Descriptions are shown in the official language in which they were submitted.
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CONFOCAL LASER EYE SURGERY SYSTEM AND IMPROVED
CONFOCAL BYPASS ASSEMBLY
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of and claims priority to
U.S. Patent
.. Application Serial No. 14/576,593, Attorney Docket No. 0M763USO, titled
"Confocal Laser
Eye Surgery Systems," filed December 19, 2014, which claims priority to U.S.
Provisional
Application Serial No. 61/970,854, filed March 26, 2014, and to U.S.
Provisional Application
Serial No. 62/043,749, filed August 29, 2014, the entire contents of all of
which applications are
incorporated herein as if fully set forth. Full Paris Convention priority is
hereby expressly
.. reserved.
FIELD OF THE INVENTION
[0002] The field of the present invention generally relates to laser
surgery systems, and
more particularly, to systems and methods for imaging and treating the eye.
BACKGROUND OF THE INVENTION
[0003] Many patients may have visual errors associated with the refractive
properties of the
eye such as nearsightedness, farsightedness and astigmatism. Astigmatism may
occur when the
corneal curvature is unequal in two or more directions. Nearsightedness can
occur when light
focuses before the retina, and farsightedness can occur with light refracted
to a focus behind the
retina.
[0004] There are numerous prior surgical approaches for reshaping the cornea.
Over the years,
surgical laser systems have replaced manual surgical tools in ophthalmic
procedures. Indeed,
with applications in a variety of different procedures, surgical laser systems
have become
ubiquitous in eye surgery. For instance, in the well-known procedure known as
LASIK (laser-
assisted in situ keratomileusis), a laser eye surgery system employing
ultraviolet radiation is used
for ablating and reshaping the anterior surface of the cornea to correct a
refractive condition,
such as myopia or hyperopia.
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[0005] Laser eye surgery systems have also been developed for
cataract procedures.
These systems can be used for various surgical procedures, including for
instance: (1) creating
one or more incisions in the cornea, or in the limbus to reshape the cornea,
(2) creating one or
more incisions in the cornea to provide access for a cataract surgery
instrument and/or to provide
access for implantation of an intraocular lens, (3) incising the anterior lens
capsule (anterior
capsulotomy) to provide access for removing a cataractous lens, (4) segmenting
and/or
fragmenting a cataractous lens, and/or (5) incising the posterior lens capsule
(posterior
capsulotomy) for various cataract-related procedures.
[0006] For example, arcuate incisions are conical incisions made in
the cornea.
.. Typically, to prevent an incision from penetrating entirely through the
cornea, an arcuate incision
is made that does not penetrate the posterior surface of the cornea. Some
laser eye surgery
systems are capable of making intrastromal arcuate incisions by a laser where
the incision is
completely contained within the thickness of the cornea and does not penetrate
the anterior or
posterior surfaces of the cornea.
[0007] Typically, some form of imaging is used with laser cataract surgery
systems to
image and identify one or more surfaces of the eye. In some instances, it may
be desirable to
accurately identify, detect, and/or image various surfaces of the cornea
before, during, or after
surgery. For example, in some situations, it may be desirable to accurately
determine a thickness
of the cornea by imaging and/or by identifying an anterior and a posterior
surface of the cornea.
However, the cornea's birefringent characteristics may make the
identification, detection, and/or
imaging of the posterior surface of the corneal more difficult.
[0008] In other situations, an image of a proposed laser cut arcuate
incision is overlaid on
top of an imaged cornea for a surgeon to verify that the proposed incision
does not penetrate the
posterior surface of the cornea. If the incision is intrastromal, the surgeon
also verifies that the
proposed incision does not penetrate the anterior surface. However, the image
provided is
typically just a cross-sectional image of the cut overlaid on the cornea,
showing only one plane
of the proposed incision. While the surgeon can verify that the proposed
incision of the
displayed cross-sectional plane is correct, they cannot verify that the
incision is correct over the
entire length of the proposed cut. Thus, laser surgery and imaging systems
with improved
characteristics to allow better imaging, detection and treatment may be
beneficial.
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SUMMARY OF THE INVENTION
[0009] Accordingly, this disclosure provides imaging systems and
related methods that
can be used in suitable laser surgery systems, including laser eye surgery
systems, so as to
obviate one or more problems due to limitations and disadvantages of the
related art. In many
embodiments, improved methods, devices and systems are provided for imaging
the eye and
various ocular structures, such as the surfaces of the cornea, the crystalline
lens, and so on. For
instance, some embodiments provide imaging and identification of the posterior
surface of the
cornea as well as of the crystalline lens surface. Systems and methods are
also provided for
imaging ocular structures in a low power imaging mode, and for treating those
structures in a
high power treatment mode. In other embodiments, systems and methods are
provided for
imaging a surgical procedure on an ocular structure by previewing an incision
over its entire
length.
[0010] In some embodiments, methods of imaging an eye are provided.
These methods
may include focusing a first electromagnetic radiation beam to a focal point
at a location in the
eye, the first electromagnetic radiation beam having a first polarization. The
methods may
further include focusing a second electromagnetic radiation beam to a focal
point at the location
in the eye, the second electromagnetic radiation beam having a second
polarization which is
different from the first polarization. The methods may further include
generating a first intensity
signal indicative of an intensity of electromagnetic radiation reflected from
the eye in response to
the step of focusing the first electromagnetic radiation beam, and generating
a second intensity
signal indicative of an intensity of electromagnetic radiation reflected from
the eye in response to
the step of focusing the second electromagnetic radiation beam. One or more
images of the eye
may then be generated with the first and second intensity signals and utilized
for treatment
planning.
[0011] Optionally, the first and second electromagnetic radiation beams may
be focused
using a beam scanner. The methods may further include scanning the focal point
of the first
electromagnetic radiation beam to a plurality of different locations in a
first region of the eye,
and scanning the focal point of the second electromagnetic radiation beam to a
plurality of
different locations in a second region of the eye. A first intensity profile
may be generated that is
indicative of intensities of electromagnetic radiation reflected from the eye
in response to the
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step of scanning the focal point of the first electromagnetic radiation beam.
A second intensity
profile may be generated that is indicative of intensities of electromagnetic
radiation reflected
from the eye in response to the step of scanning the focal point of the second
electromagnetic
radiation beam. In some embodiments, one image of the eye is generated per the
first and
second intensity profiles. A beam scanner may include an XY-scan device that
is configured to
deflect the first and second electromagnetic radiation beams in two dimensions
transverse to a
propagation of first and second electromagnetic radiation beams. The focal
point of the first and
second electromagnetic radiation beam may be scanned in the two dimensions
using the XY-
scan device according to some embodiments, and may thereby provide an image of
the eye with
at least two dimensions.
[0012] Optionally, the beam scanner may further include a Z-scan
device that is
configured to vary a convergence depth of the beam within the eye. In some
embodiments, the
Z-scan device may vary a convergence angle of the beam. The focal point of the
first and second
electromagnetic radiation beam may then be scanned in the three dimensions
using the XY-scan
device and the Z- scan device. Accordingly, the image of the eye may be three-
dimensional
according to some embodiments.
[0013] In some embodiments, the first and second intensity signals
may be generated by
a sensor. The sensor may be a confocal sensor. The methods may further include
the step of
blocking reflected electromagnetic radiation from reaching the sensor, where
the electromagnetic
radiation has reflected from eye locations other than the location of the
focal point of the first
and second electromagnetic radiation beams.
[0014] In some methods, the first electromagnetic radiation beam may
be generated by
passing an electromagnetic radiation beam through a wave plate in a first
position so as to
polarize the electromagnetic radiation beam with the first polarization. The
wave plate may be
rotated by an angle to a second position. The second electromagnetic radiation
beam may be
generated by passing the electromagnetic radiation beam through the wave plate
in the second
position.
[0015] Optionally, the wave plate may be a one-quarter wave plate. In
some
embodiments, the wave plate may be rotated by an acute angle for generating
the second
electromagnetic radiation beam. In some embodiments, the wave plate may be
rotated ninety
degrees for generating the second electromagnetic radiation beam. In some
embodiments, the
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first and second electromagnetic radiation beams may be polarized with the
first and second
polarizations by using a Faraday rotator, or a rotating beam-splitter.
[0016] In some embodiments, the method may include the step of
passing
electromagnetic radiation reflected from the eye in response to the step of
focusing the first
electromagnetic radiation beam through the wave plate in the first position.
Further,
electromagnetic radiation reflected from the eye in response to the step of
focusing the second
electromagnetic radiation beam may be passed through the wave plate in the
second position.
[0017] In additional embodiments, methods of imaging an eye are
provided, where the
method includes scanning a focal point of a first electromagnetic radiation
beam to a plurality of
.. locations in the eye, where the first electromagnetic radiation beam has a
first polarization. The
methods may further include scanning a focal point of a second electromagnetic
radiation beam
to at least a portion of the plurality of locations in the eye, where the
second electromagnetic
radiation beam has a second polarization different than the first
polarization. A first intensity
profile indicative of an intensity of electromagnetic radiation reflected from
the eye may be
.. generated in response to the step of scanning the first electromagnetic
radiation beam. And, a
second intensity profile indicative of an intensity of electromagnetic
radiation reflected from the
eye may be generated in response to the step of scanning the second
electromagnetic radiation
beam. An image of the eye may be produced using the first and second intensity
profiles.
[0018] Optionally, the method may include receiving a plurality of
parameters
.. corresponding to the treatment planning, generating a three-dimensional
representation of the
treatment planning, mapping the three-dimensional representation onto the
image of the eye, and
displaying the mapped image for the treatment planning. The treatment planning
may include
an arcuate incision. The system can verify that the arcuate incision lies
within the cornea. The
received parameters may include a treatment axis and a treatment length
transverse to the axis.
.. The image of the eye may be in a plane of the treatment axis and the
treatment length. In some
embodiments, the three-dimensional representation is mapped onto the image of
the eye by
projecting the three-dimensional representation onto a two-dimensional space.
The displayed
image may include a cornea of the eye including an anterior and posterior. The
anterior and
posterior of the cornea are optionally highlighted. The treatment planning may
also include one
of a primary and side-port incision.
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[0019] In some embodiments, the methods may be for imaging a cornea
of the eye,
where the cornea has an anterior surface and a posterior surface. The anterior
surface of the
cornea may be identified using the first intensity profile, and the posterior
surface of the cornea
may be identified using at least a portion of the second intensity profile.
[0020] In some embodiments, methods of imaging a cornea may include the
step of
generating a first electromagnetic radiation beam using a beam source and
passing the first
electromagnetic radiation beam through a wave plate. The first electromagnetic
radiation beam
may be propagated to a beam scanner. The first electromagnetic radiation beam
may be focused
to a focal point at a location in the cornea of the eye using the beam
scanner. A first reflected
electromagnetic radiation from the focal point may be received after focusing
the first
electromagnetic radiation beam. The first received electromagnetic radiation
may be directed
through the wave plate and towards a sensor. A first intensity signal may be
generated that is
indicative of an intensity of the first received electromagnetic radiation.
Thereafter, the wave
plate may be rotated at an angle after generating the first intensity signal.
A second
electromagnetic radiation beam may be passed through the rotated wave plate
and focused to a
focal point at the location in the cornea of the eye. A second reflected
electromagnetic radiation
from the focal point may be received in response to the step of focusing the
second
electromagnetic radiation beam. The second received electromagnetic radiation
may be directed
through the rotated wave plate and toward the sensor. A second intensity
signal may be
generated that is indicative of an intensity of the second received
electromagnetic radiation. The
anterior surface of the cornea may be identified using the first intensity
signal and at least some
portions of the posterior surface of the cornea may be identified using the
second intensity signal.
[0021] In some embodiments, the method may include the steps of
generating an image
of the eye using the identified anterior surface and posterior surface of the
cornea, receiving a
plurality of parameters corresponding to a treatment plan, generating a three-
dimensional
representation of the treatment plan, mapping the three-dimensional
representation onto the
image of the eye, and displaying the mapped image for verification.
[0022] Optionally, the treatment plan may include an arcuate
incision. The arcuate
incision may be verified to lie within the cornea. The received parameters may
include a
treatment axis and a treatment length transverse to the axis. The image of the
eye may be in a
plane of the treatment axis and the treatment length. In some embodiments, the
three-
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dimensional representation is mapped onto the image of the eye by projecting
the three-
dimensional representation onto a two-dimensional space. The anterior surface
and posterior
surface of the cornea may be highlighted. Alternatively, the treatment plan
includes one of a
primary and side-port incision.
[0023] Certain aspects of the present invention provide methods of imaging
a cornea,
where the cornea has a first region with a first birefringence and a second
region with a second
birefringence. The methods may include a step of directing a first
electromagnetic radiation
beam through the first region of the cornea to a first location in the eye,
where the first
electromagnetic radiation beam may have a first polarization. A second
electromagnetic
.. radiation beam may be directed through the second region of the cornea to a
second location in
the eye, where the second electromagnetic radiation beam may have a second
polarization
different from the first polarization. An image of the eye may be generated
that encompasses the
first and second locations using electromagnetic radiation signals reflected
from the eye in
response to the steps of directing the first and second electromagnetic
radiation beams.
[0024] In still other aspects of the present invention, where methods of
imaging an eye
are provided, the methods may include the step of generating an
electromagnetic radiation beam
using a beam source. The electromagnetic radiation beam may be elliptically
polarized, and may
be focused to a focal point in the eye. Further, the focal point of the
elliptically polarized
electromagnetic radiation beam may be scanned to a plurality of different
locations in the eye.
Electromagnetic radiation reflected from the focal point may be received in
response to the step
of scanning the elliptically polarized electromagnetic radiation. This
received reflected
electromagnetic radiation may be directed toward a sensor, and an intensity
profile may be
generated that is indicative of an intensity of the received reflected
electromagnetic radiation. A
first surface and a second surface of the eye may be identified using the
intensity profile.
[0025] In some embodiments, the methods may further include the step of
passing the
reflected electromagnetic radiation through an aperture to block reflected
electromagnetic
radiation from eye locations other than the location of the focal point of the
elliptically polarized
electromagnetic radiation beam.
[0026] In some embodiments, the methods may further include the step
of generating an
.. image of the eye using the identified first surface and second surface of
the cornea, receiving a
plurality of parameters corresponding to a treatment plan, generating a three-
dimensional
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representation of the treatment plan, mapping the three-dimensional
representation onto the
image of the eye, and displaying the mapped image for verification. The
treatment plan may
include an arcuate incision. The arcuate incision may be verified to lie
within the cornea. The
received parameters may include a treatment axis and a treatment length
transverse to the axis.
The image of the eye may be in some embodiments in a plane of the treatment
axis and the
treatment length. The three-dimensional representation may be mapped onto the
image of the
eye by projecting the three-dimensional representation onto a two-dimensional
space. The first
surface and second surface of the cornea are optionally highlighted.
Alternatively, the treatment
plan comprises one of a primary and side-port incision.
[0027] In other embodiments, systems for imaging an eye are provided,
wherein the
systems may include a laser beam source configured to output a beam along a
beam path toward
the eye. A beam scanner may be included to focus the outputted beam to a focal
point at a
location in the eye. The systems may include a variable axis polarization
system positioned
along the beam path between the laser beam source and the eye. The
polarization system may be
configured to polarize an outputted beam with a first polarization or a second
polarization. The
polarization system may polarize an outputted beam with the first polarization
when in a first
configuration, and may polarize the outputted beam with the second
polarization when in a
second configuration. The system may further include a sensor positioned to
receive reflected
electromagnetic radiation from the eye.
[0028] In some embodiments, the wave plate may be further positioned and
configured to
receive reflected electromagnetic radiation from the focal point before the
reflected
electromagnetic radiation reaches the sensor. Optionally, the systems may
further include a
polarizing beam-splitter positioned to direct the reflected electromagnetic
radiation that passed
through the wave plate to the sensor. An aperture may be positioned to block
reflected
electromagnetic radiation from eye locations other than the location of the
focal point of the
outputted beam. The wave plate may be a one-quarter wave plate.
[0029] In some aspects, the wave plate may be rotatable between the
first position and
the second position. The wave plate may rotate forty-five degrees between the
first position and
the second position. Optionally, the wave plate may rotate ninety degrees
between the first
position and the second position. The beam scanner may include an XY-scan
device and a Z-
scan device. The XY-scan device may be configured to deflect the outputted
beam in two
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dimensions transverse to a propagation of outputted beam, while the Z-scan
device may be
configured to vary a convergence depth of the beam.
[0030] In some embodiments, the systems may include a processor
generating an image
of the eye using an output of the sensor. A user interface device receiving a
plurality of
parameters corresponding to a treatment plan. The processor may generate a
three-dimensional
representation of the treatment plan and map the three-dimensional
representation onto the image
of the eye. A display system displays the mapped image for verification. The
treatment
planning may include an arcuate incision. The processor may verify that the
arcuate incision lies
within the cornea. The parameters may include a treatment axis and a treatment
length
transverse to the axis. The image of the eye may be in a plane of the
treatment axis and the
treatment length. In some embodiments, the three-dimensional representation
may be mapped
onto the image of the eye by projecting the three-dimensional representation
onto a two-
dimensional space. The displayed image may include a cornea of the eye
including an anterior
and posterior. The anterior and posterior of the cornea are optionally
highlighted. Alternatively,
the treatment planning comprises one of a primary and side-port incision.
[0031] Certain aspects of the invention disclose systems for imaging
an eye using
elliptically polarized light. The system may include a laser beam source
configured to output a
beam along a beam path toward the eye. A wave plate may be positioned along
the beam path
between the laser beam source and the eye and may be configured to
elliptically polarize an
.. outputted beam. A beam scanner may be configured to focus the elliptically
polarized outputted
beam to a focal point at a location in the eye. A sensor may be positioned to
receive reflected
electromagnetic radiation from the focal point. Further, an aperture may be
positioned to block
reflected electromagnetic radiation from eye locations other than the location
of the focal point
of the outputted beam.
[0032] In some embodiments, the systems may further include a processor
generating an
image of the eye using an output of the sensor, a user interface device
receiving a plurality of
parameters corresponding to a treatment plan. The processor may generate a
three-dimensional
representation of the treatment plan, and map the three-dimensional
representation onto the
image of the eye. A display system displays the mapped image for verification.
The treatment
planning may include an arcuate incision.
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[0033] In another embodiment, a laser-based eye surgery system for
treating and imaging
an eye may include a laser delivery system for delivering an electromagnetic
radiation beam to a
target in the eye, an attenuator for polarizing the electromagnetic radiation
beam, a shutter for
allowing or blocking the electromagnetic radiation beam, a beam-splitter for
separating the
electromagnetic radiation beam, where the beam-splitter may be substantially
non-polarizing for
reflecting a returning confocal beam. A bypass assembly for directing the
electromagnetic
radiation beam and a sensor for imaging the eye may be included.
[0034] In many of the embodiments, the electromagnetic radiation beam
may be directed
to bypass the non-polarized beam-splitter in a treatment mode. The
electromagnetic radiation
beam may be directed toward the non-polarized beam-splitter while bypassing
the bypass
assembly in an imaging mode. The bypass assembly may include one or more
mirrors or prisms.
The electromagnetic radiation beam when bypassing the non-polarized beam-
splitter provides a
high power level for treatment. The electromagnetic radiation beam when
directed toward the
non-polarized beam-splitter provides a low power level for imaging.
[0035] In many embodiments of the system, the system includes a processor
generating
an image of the eye using an output of the sensor and a user interface device
receiving a plurality
of parameters corresponding to a treatment plan. The processor generates a
three-dimensional
representation of the treatment plan, and maps the three-dimensional
representation onto the
image of the eye. A display system displays the mapped image for verification.
The treatment
planning may include an arcuate incision.
[0036] In another embodiment, a method for treating and imaging an
eye using a laser-
based eye surgery system includes the steps of generating an electromagnetic
radiation beam,
delivering the electromagnetic radiation beam to a target in the eye,
directing the electromagnetic
radiation beam to a bypass assembly for treatment, and directing the
electromagnetic radiation
beam toward a beam-splitter for imaging. The beam-splitter may be
substantially non-polarizing
for reflecting a returning confocal beam. The step of directing the
electromagnetic radiation
beam to a bypass assembly further may provide a high power level for
treatment. The step of
directing the electromagnetic radiation beam toward a beam-splitter further
may provide a low
power level for imaging.
[0037] Some embodiments of the method for treating and imaging an eye may
include
the steps of generating an image of the eye in response to the step of
directing the
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electromagnetic radiation beam in the low power level for imaging, receiving a
plurality of
parameters corresponding to treatment planning, generating a three-dimensional
representation
of the treatment planning, mapping the three-dimensional representation onto
the image of the
eye, and displaying the mapped image for the treatment planning. The treatment
planning may
include an arcuate incision.
[0038] Another embodiment provides a method of reversibly bypassing
an imaging
assembly in an optical path of a laser surgical system. The method includes
using a beam source
to generate an electromagnetic beam. The electromagnetic beam is propagated
from the beam
source to a scanner along an optical path that includes a first optical
element associated with a
confocal detection assembly. The electromagnetic beam is focused to a focal
point at a location
within the eye, and a scanner scans the focal point to different locations
within the eye. A
portion of the electromagnetic beam is reflected from the focal point location
back along the
optical path to the first optical element, which diverts a portion of the
reflected electromagnetic
radiation to a sensor. The sensor generates an intensity signal indicative of
the intensity of a
portion of the electromagnetic beam reflected from the focal point location
and propagated to the
sensor via the first optical element. The method includes reversibly diverting
the
electromagnetic beam along a diversion optical path around the first optical
element, and
preferably, the beam direction and position are substantially the same at the
entry of and exit
from the diversion optical path in a direction transverse to the direction of
propagation of the
electromagnetic beam.
[0039] The first optical element is preferably a beam-splitter that
directs a portion of the
reflected electromagnetic radiation to the sensor. The beam-splitter is
preferably stationary. In
one embodiment, the beam-splitter is not a polarizing beam-splitter, i.e., its
ability to split a beam
is not based on a polarization property of the reflected light.
[0040] In many embodiments of the method, the electromagnetic beam can be
configured
along the optical path so as to not modify tissue. For example, the
electromagnetic beam can
have an energy level below a threshold level for tissue modification.
Alternatively, the
electromagnetic beam can be configured at an energy level designed to modify
tissue.
[0041] The electromagnetic beam can have any suitable configuration.
For example, the
electromagnetic beam can include a plurality of laser pulses having a
wavelength between 320
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nanometers and 430 nanometers. As another example, the electromagnetic beam
can include a
plurality of laser pulses having a wavelength between 800 nanometers and 1100
nanometers.
[0042] In another embodiment, a laser eye surgery system is provided.
The system
includes a light source, an eye interface device, a scanning assembly, a
confocal detection
assembly and a confocal bypass assembly. The light source is configured to
generate an
electromagnetic beam. The scanning assembly is operable to scan a focal point
of an
electromagnetic beam to different locations within the eye. The eye interface
device is
configured to interface with an eye of a patient. An optical path is
configured to propagate the
electromagnetic beam from a light source to the focal point, and also
configured to propagate a
portion of the electromagnetic beam reflected back from the focal point
location along at least a
portion of the optical path. The optical path comprises a first optical
element associated with a
confocal detection assembly that diverts a portion of the reflected
electromagnetic radiation to a
sensor. A confocal detection assembly is configured to generate an intensity
signal indicative of
intensity of a portion of the electromagnetic beam reflected from the focal
point location. The
confocal bypass assembly is configured to reversibly divert the
electromagnetic beam along a
diversion optical path around the first optical element. Preferably, the beam
position is
substantially the same at the entry of, and at the exit from the diversion
optical path in a direction
transverse to the direction of propagation of the electromagnetic beam.
Further, the propagation
direction is the same at the entry and the exit of the diversion optical path.
[0043] The scanning assembly comprises a Z-scan device operable to vary the
location of the
focal point in the direction of propagation of the electromagnetic beam, and
an XY-scan device
operable to vary the location of the focal point transverse to the direction
of propagation of the
electromagnetic beam.
[0044] The detection assembly preferably comprises an aperture configured to
block portions
of the electromagnetic beam reflected from locations other than the focal
point from reaching the
sensor.
[0045] The first optical element is generally associated with a confocal
imaging assembly, and
is preferably a beam-splitter that directs a portion of the reflected
electromagnetic radiation to the
sensor. The beam-splitter is preferably stationary. In one embodiment, the
beam-splitter is not a
polarizing beam-splitter, i.e., its ability to split a beam is not based on a
polarization property of
the reflected light.
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[0046] In one embodiment, the confocal bypass assembly comprises a bypass
prism. The
confocal bypass assembly reversibly moves the bypass prism into and out of the
optical path,
thereby diverting the electromagnetic beam along a diversion optical path
around an optical
element of a confocal detection assembly operably to divert a portion of the
electromagnetic
beam to a sensor. In a preferred embodiment, the diversion optical path
diverts the
electromagnetic beam only around the optical element. In one embodiment, the
confocal bypass
prism diverts the electromagnetic beam around only the optical element that
directs a portion of
the reflected electromagnetic radiation to the sensor.
[0047] In another embodiment, the laser eye surgery system may
include a laser delivery
system for delivering an electromagnetic radiation beam to a target in an eye,
a beam expander
coupled to the laser delivery system for adjusting the diameter of the
electromagnetic radiation
beam, an attenuator coupled to the expander for polarizing the electromagnetic
radiation beam, a
shutter coupled to the attenuator for allowing or blocking the electromagnetic
radiation beam,
and a sensor. A bypass assembly is coupled to the shutter for propagating the
electromagnetic
radiation beam to bypass a non-polarized beam-splitter and dump in a treatment
mode, and for
directing the electromagnetic radiation beam toward the non-polarized beam-
splitter and dump in
an imaging mode while bypassing the bypass assembly. In another embodiment,
the eye surgery
system delivers the electromagnetic radiation beam in a high power level for
treatment, and in a
low power level for imaging.
[0048] In many embodiments, the bypass assembly includes one or more
mirrors or
prisms. One or more wave plates may be provided to enable confocal imaging of
the target in
the eye. One or more wave plate angles for imaging ocular structures of the
target in the eye
may compensate for birefringence effects in the imaged structures.
[0049] Optionally, the system may include a processor generating an
image of the eye
using an output of the sensor and a user interface device receiving a
plurality of parameters
corresponding to a treatment plan. The processor may generate a three-
dimensional
representation of the treatment plan and map the three-dimensional
representation onto the image
of the eye. A display system may display the mapped image for verification.
The treatment
planning may include an arcuate incision.
[0050] In still other aspects of the present invention, where methods of
imaging an eye
are provided, the methods may include the step of focusing a first
electromagnetic radiation
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beam to a focal point at a location in the eye and focusing a second
electromagnetic radiation
beam to a focal point at the location in the eye. A first intensity signal is
generated indicative of
an intensity of electromagnetic radiation reflected from the eye in response
to the step of
focusing the first electromagnetic radiation beam. A second intensity signal
is generated
indicative of an intensity of electromagnetic radiation reflected from the eye
in response to the
step of focusing the second electromagnetic radiation beam. One or more images
of the eye are
generated with the first and second intensity signals for treatment planning.
A plurality of
parameters are received corresponding to the treatment planning. A three-
dimensional
representation of the treatment planning is generated. The three-dimensional
representation is
mapped onto the image of the eye. The mapped image is displayed for the
treatment planning.
[0051] In another embodiment, a laser surgery system includes a laser
beam source
configured to output a beam along a beam path toward the eye. A beam scanner
is configured to
direct the outputted beam to a plurality of locations in the eye. A sensor is
positioned to receive
reflected electromagnetic radiation from the eye. A processor is configured to
generate one or
more images of the eye with the first and second intensity signals for
treatment planning. A user
input device is configured to receive a plurality of parameters corresponding
to the treatment
planning. The processor generates a three-dimensional representation of the
treatment planning,
maps the three-dimensional representation onto the image of the eye. A display
is configured to
display the mapped image for the treatment planning.
[0052] Another embodiment of the invention is directed to a method of
reversibly separating
an imaging assembly from an optical path in a laser surgical system, the
method comprising:
using a beam source to generate an electromagnetic beam; propagating the
electromagnetic beam
from the beam source to a scanner along an optical path, the optical path
comprising a first
optical element that attenuates the electromagnetic beam, the first optical
element being
positioned between the beam source and the scanner; focusing the
electromagnetic beam to a
focal point at a location within the eye; using the scanner to scan the focal
point to different
locations within the eye; propagating a portion of the electromagnetic beam
reflected from the
focal point location back along the optical path to the first optical element,
the first optical
element diverting a portion of the reflected electromagnetic radiation to a
sensor; using the
sensor to generate an intensity signal indicative of an intensity of a portion
of the
electromagnetic beam reflected from the focal point location and propagated to
the sensor via the
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first optical element; and reversibly inserting a confocal bypass assembly
into the optical path,
diverting the electromagnetic beam along a diversion optical path around the
first optical
element, wherein the beam direction and position are substantially the same at
the entry of and
exit from the diversion optical path in a direction transverse to the
direction of propagation of the
electromagnetic beam, wherein the confocal bypass assembly automatically exits
the optical path
when a power loss occurs to one or more components, such as the confocal
bypass assembly. In
some embodiments, the first optical element is a beam-splitter that directs a
portion of the
reflected electromagnetic radiation to the sensor. The beam-splitter may be
stationary.
Preferably, the beam splitter is not a polarizing beam splitter and transmits
less than 20% of the
incident light, more preferably less than 10%, more preferably less than 5%
and more preferably
1% or less of the incident light. The electromagnetic beam is preferably
configured to modify
tissue when the electromagnetic beam when diverted along the diversion optical
path.
[0053] In another embodiment, an eye surgery system comprises: a light source
for generating
an electromagnetic beam; an eye interface device configured to interface with
an eye of a patient;
a scanning assembly supporting the eye interface device and operable to scan a
focal point of an
electromagnetic beam to different locations within the eye; a light source
configured to generate
the electromagnetic beam; an optical path configured to propagate the
electromagnetic beam
from the light source to the focal point and also configured to propagate a
portion of the
electromagnetic beam reflected from the focal point location back along the
optical path, the
optical path comprising a first optical element that attenuates the
electromagnetic beam in a
direction from the light source to the scanner and that also diverts a portion
of the reflected
electromagnetic radiation to a sensor; a detection assembly configured to
generate an intensity
signal indicative of intensity of a portion of the electromagnetic beam
reflected from the focal
point location; and a confocal bypass assembly configured to reversibly divert
the radiation
beam along a diversion optical path around the first optical element when the
confocal bypass
assembly is inserted into the optical path, wherein the confocal bypass
assembly is configured to
exit the optical path upon a loss of power to one or more components of the
eye surgery system.
The first optical element is preferably a nonpolarizing beam-splitter that
directs a portion of the
reflected electromagnetic radiation to the sensor. Preferably, the beam-
splitter transmits less
than 20% of the incident light, more preferably less than 10%, more preferably
less than 5% and
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more preferably 1% or less of the incident light. The confocal bypass assembly
preferably
comprises a bypass prism.
[0054] In another embodiment, a method of reversibly separating an
imaging assembly
from an optical path in a laser surgical system comprises :using a beam source
to generate an
electromagnetic beam; propagating the electromagnetic beam from the beam
source to a scanner
along an optical path, the optical path comprising a non-polarizing first
optical element that
attenuates the electromagnetic beam, the first optical element being
positioned between the beam
source and the scanner; focusing the electromagnetic beam to a focal point at
a location within
the eye; using the scanner to scan the focal point to different locations
within the eye;
propagating a portion of the electromagnetic beam reflected from the focal
point location back
along the optical path to the first optical element, the first optical element
diverting a portion of
the reflected electromagnetic radiation to a sensor; using the sensor to
generate an intensity
signal indicative of an intensity of a portion of the electromagnetic beam
reflected from the focal
point location and propagated to the sensor via the first optical element; and
reversibly inserting
a confocal bypass assembly into the optical path, diverting the
electromagnetic beam along a
diversion optical path around the first optical element, wherein the beam
direction and position
are substantially the same at the entry of and exit from the diversion optical
path in a direction
transverse to the direction of propagation of the electromagnetic beam. The
first optical element
is a beam-splitter that directs a portion of the reflected electromagnetic
radiation to the sensor,
and preferably the beam-splitter transmits less than 20% of the incident
light, more preferably
less than 10%, more preferably less than 5% and more preferably 1% or less of
the incident light.
[0055] This summary and the following description are merely
exemplary, illustrative,
and explanatory, and are not intended to limit, but to provide further
explanation of the invention
as claimed. Additional features, aspects, objects and advantages of
embodiments of this
invention are set forth in the descriptions, drawings, and the claims, and in
part, will be apparent
from the drawings and detailed description, or may be learned by practice. The
claims are
incorporated by reference.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0056] The novel features of the invention are set forth with
particularity in the appended
claims. A better understanding of the features and advantages of the present
invention will be
obtained by referring to the following detailed description that sets forth
illustrative
embodiments using principles of the invention, as well as to the accompanying
drawings of
which:
[0057] FIG. 1 is a schematic diagram of a laser surgery system
according to an
embodiment of the invention.
[0058] FIG. 2 is a schematic diagram of the laser surgery system of
FIG. 1 according to
an embodiment of the invention.
[0059] FIG. 3 is a simplified process of imaging and/or modifying an
intraocular target
according to an embodiment of the invention.
[0060] FIGS. 4, 5, and 6 are simplified processes that can be
accomplished as part of the
process of FIG. 3 according to an embodiment of the invention.
[0061] FIG. 7A is a process for imaging an eye, according to an embodiment
of the
invention.
[0062] FIGS. 7B-7C show two exemplary intensity profiles of a cornea
of an eye
generated according to the process shown in FIG. 7A.
[0063] FIG. 8 is an exemplary illustration showing a plurality of
regions of the cornea of
an eye, wherein according to an embodiment of the invention, the regions may
have varying
birefringence properties.
[0064] FIG. 9 is another process for imaging an eye according to an
embodiment of the
invention.
[0065] FIG. 10A and FIG. 10B are a schematic diagrams of a laser
surgery system
according to another embodiment. FIG. 10A is a schematic diagram illustrating
an embodiment
in which a confocal bypass assembly is not placed in the optical path of the
electromagnetic
beam. FIG. 10B is a schematic diagram illustrating an embodiment in which a
confocal bypass
assembly is placed in the optical path of the electromagnetic beam.
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[0066] FIG. 11 is a simplified block diagram of acts of a method according to
many
embodiments, in which the laser surgery system is used to image one or more
portions of a target
tissue, such as a patient's eye.
[0067] FIG. 12 is as simplified block diagram of acts according to many
embodiments, in
which the laser surgery system is used to modify target tissue in a patients
eye.
[0068] FIG. 13 is a schematic diagram showing an illustrative embodiment of a
confocal
bypass assembly.
[0069] FIG. 14A and FIG. 14B are schematic diagrams illustrating an
embodiment, in which
the confocal bypass assembly includes a bypass prism, and wherein the optical
path in an
imaging mode is illustrated in FIG. 14A, and a diversion optical path in a non-
imaging mode
(i.e. treatment mode) is illustrated in FIG. 14B.
[0070] FIG. 15A and FIG. 15B are schematic diagrams illustrating an embodiment
of a laser
surgical system utilizing a bypass prism to switch between an imaging mode
(FIG. 15A) and a
non-imaging mode (FIG. 15B).
[0071] FIG. 16 is another schematic diagram of the laser surgery system of
FIG. 1,
according to an embodiment of the invention.
[0072] FIG. 17 is a schematic diagram of a bypass element of the
laser surgery system of
FIG. 10 according to an embodiment of the invention.
[0073] FIG. 18 is another schematic diagram of a bypass element of
the laser surgery
system of FIG. 10 according to an embodiment of the invention.
[0074] FIG. 19 is another schematic diagram of a bypass element of
the laser surgery
system of FIG. 10 according to an embodiment of the invention.
[0075] FIG. 20 is another schematic diagram of a bypass element of
the laser surgery
system of FIG. 10 according to an embodiment of the invention.
[0076] FIG. 21 is a simplified process for imaging and treating an eye
according to an
embodiment of the invention.
[0077] FIG. 22 is a simplified process of imaging an eye with a
proposed incision,
according to an embodiment of the invention.
[0078] FIGS. 23A and 23B shows an exemplary display of an incision
review for a
.. cornea of an eye generated according to an embodiment of the invention.
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[0079] FIG. 24 is another schematic diagram of the laser surgery
system of FIG. 1
according to an embodiment of the invention.
[0080] FIG. 25 is another schematic diagram of the laser surgery
system of FIG. 10A
and FIG. 10B according to an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0081] The following description describes various embodiments of the present
invention. For
purposes of explanation, specific configurations and details are set forth so
as to provide a
thorough understanding of the embodiments. It will also, however, be apparent
to one skilled in
the art that embodiments of the present invention can be practiced without
certain specific
.. details. Further, to avoid obscuring the embodiment being described,
various well-known
features may be omitted or simplified in the description.
[0082] 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.
[0083] Systems for imaging and/or treating a patient's eye are
provided. In many
embodiments, a free-floating mechanism provides a variable optical path by
which a portion of
an electromagnetic beam reflected from a focal point disposed within the eye
is directed to a path
length insensitive imaging assembly, such as a confocal detection assembly. In
many
.. embodiments, the free-floating mechanism is configured to accommodate
movement of the
patient while maintaining alignment between an electromagnetic radiation beam
and the patient.
The electromagnetic radiation beam can be configured for imaging the eye, can
be configured for
treating the eye, and can be configured for imaging and treating the eye.
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[0084] FIG. 1 schematically illustrates a laser surgery system 10
according to many
embodiments. The laser surgery system 10 may include a laser assembly 12, a
confocal
detection assembly 14, a free- floating mechanism 16, a scanning assembly 18,
an objective lens
assembly 20, and a patient interface device 22. The patient interface device
22 may be
configured to interface with a patient 24. The patient interface device 22 may
be supported by
the objective lens assembly 20, which may be supported by the scanning
assembly 18, which
may be supported by the free-floating mechanism 16. The free-floating
mechanism 16 may have
a portion having a fixed position and orientation relative to the laser
assembly 12 and the
confocal detection assembly 14.
[0085] In some embodiments, the patient interface device 22 can be
configured to be
coupled to an eye of the patient 24 using a vacuum as described in U.S.
Publication No. US
2014-0128821A1 (co pending U.S. Patent Application serial number: 14/068,994,
entitled
"Liquid Optical Interface for Laser Eye Surgery System," filed October 31,
2013), the entire
disclosure of which is incorporated herein by reference. The laser surgery
system 10 can further
optionally include a base assembly 26 that can be fixed in place or be
repositionable. For
example, the base assembly 26 can be supported by a support linkage that is
configured to allow
selective repositioning of the base assembly 26 relative to a patient, and/or
to allow securing the
base assembly 26 in a selected fixed position relative to the patient. Such a
support linkage can
be a fixed support base, or a movable cart that can be repositioned to a
suitable location adjacent
to a patient. In many embodiments, the support linkage includes setup joints
with each setup
joint being configured to permit selective articulation of the setup joint,
and can be selectively
locked to prevent inadvertent articulation of the setup joint, thereby
securing the base assembly
26 in a selected fixed position relative to the patient when the setup joints
are locked.
[0086] In many embodiments, the laser assembly 12 may be configured
to emit an
electromagnetic radiation beam 28. The beam 28 can include a series of laser
pulses of any
suitable energy level, duration, and repetition rate.
[0087] In many embodiments, the laser assembly 12 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 to
image and/or to modify an intraocular target as compared to laser pulses
having longer durations.
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[0088] The laser assembly 12 may produce laser pulses having a
wavelength suitable to
treat and/or to image tissue. For example, the laser assembly 12 can be
configured to emit an
electromagnetic radiation beam 28 such as that emitted by any of the laser
surgery systems
described in U.S. Publication No. US 2014-0157190A1 (co-pending U.S. Patent
Application
serial number 14/069,044, entitled "Laser Eye Surgery System," filed October
31, 2013) and
U.S. Publication No. US 2011-0172649A1 (co-pending U.S. Patent Application
serial number
12/987,069, entitled "Method and System For Modifying Eye Tissue and
Intraocular Lenses,"
filed January 7, 2011), the full disclosures of which are incorporated herein
by reference. In an
embodiment, the laser assembly 12 may produce laser pulses having a wavelength
in the range of
1020 nm to 1050 nm. In another embodiment, the laser assembly 12 may have a
diode-pumped
solid-state configuration with a 1030 (+/-5) nm center wavelength. In yet
another embodiment,
the laser assembly 12 may produce laser pulses having a wavelength 320 nm to
430 nm. For
example, the laser assembly 12 may include an Nd:YAG laser source operating at
the 3rd
harmonic wavelength (355 nm), and producing pulses having pulse durations in
the range of 50
picoseconds to 15 nanoseconds. Depending on the spot size, the typical pulse
energies can be in
the nano Joule to micro Joule range. The laser assembly 12 can also include
two or more lasers
of any suitable configuration.
[0089] The laser assembly 12 may include control and conditioning
components. In an
embodiment, the control components may include 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. The
conditioning components may
include an adjustable zoom assembly 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.
[0090] In many embodiments, the laser assembly 12 and the confocal
detection assembly
14 may have fixed positions relative to the base assembly 26. The beam 28
emitted by the laser
assembly 12 may propagate along a fixed optical path through the confocal
detection assembly
14 to the free-floating mechanism 16. The beam 28 may propagate through the
free-floating
mechanism 16 along a variable optical path 30, which may deliver the beam 28
to the scanning
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assembly 18. In many embodiments, the beam 28 emitted by the laser assembly 12
may be
collimated so that the beam 28 is not impacted by patient movement-induced
changes in the
length of the optical path between the laser assembly 12 and the scanner 16.
The scanning
assembly 18 may be operable to scan the beam 28 (e.g., via controlled variable
deflection of the
beam 28) in at least one dimension. In many embodiments, the scanning assembly
18 is operable
to scan the beam 28 in two dimensions transverse to the direction of
propagation of the beam 28,
and may be further operable to scan the location of a focal point of the beam
28 in the direction
of propagation of the beam 28. The scanned beam may be emitted from the
scanning assembly
18 to propagate through the objective lens assembly 20, through the interface
device 22, and to
the patient 24.
[0091] The free-floating mechanism 16 may be configured to
accommodate a range of
movement of the patient 24 relative to the laser assembly 12 and the confocal
detection assembly
14 in one or more directions while maintaining alignment of the beam 28
emitted by the
scanning assembly 18 with the patient 24. For example, the free-floating
mechanism 16 may be
configured to accommodate a range movement of the patient 24 in any direction
defined by any
combination of unit orthogonal directions (X, Y, and Z).
[0092] Because the patient interface device 22 may be interfaced with
the patient 24,
movement of the patient 24 may result in corresponding movement of the patient
interface
device 22, the objective lens assembly 20, and the scanning assembly 18. The
free-floating
mechanism 16 can include, for example, any suitable combination of a linkage
that
accommodates relative movement between the scanning assembly 18 and, for
example, the
confocal detection assembly 14, and optical components suitably coupled to the
linkage so as to
form the variable optical path 30. In an embodiment, the free-floating
mechanism 16 can be
configured as described in U.S. Publication No. US 2014-0316389A1 (U.S. Patent
Application
No. 14/191,095) and International Publication No. WO 2014/158615A1 (PCT
Application No.
PCT/U52014/018752, filed February 26, 2014 and entitled "Laser Surgery
System,") the entire
disclosures of which are incorporated herein by reference.
[0093] A portion of electromagnetic radiation beam 28 may reflect
from an eye tissue at
the focal point, and may propagate back to the confocal detection assembly 14.
Specifically, a
reflected portion of the electromagnetic radiation beam 28 may travel back
through the patient
interface device 22, back through the objective lens assembly 20, back through
(and de-scanned
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by) the scanning assembly 18, back through the free-floating mechanism 16
(along the variable
optical path 30), and to the confocal detection assembly 14. In many
embodiments, the reflected
portion of the electromagnetic radiation beam that travels back to the
confocal detection
assembly 14 may be directed so it is incident upon a sensor that generates an
intensity signal
indicative of the intensity of the incident portion of the electromagnetic
radiation beam. Coupled
with associated scanning of the focal point within the eye, the intensity
signal can be processed
in conjunction with the parameters of the scanning to image/locate structures
of the eye, such as
the anterior surface of the cornea, the posterior surface of the cornea, the
iris, the anterior surface
of the lens capsule, the posterior surface of the lens capsule, and so on. In
many embodiments,
the amount of the reflected electromagnetic radiation beam that travels to the
confocal detection
assembly 14 may be substantially independent of expected variations in the
length of the variable
optical path 30 due to patient movement, thereby enabling the ability to
ignore patient
movements when processing the intensity signal to image/locate structures of
the eye.
[0094] The locations of the one or more optical structures of the eye can be
determined from
the measurements obtained as discussed herein. The image of the eye may
comprise a sagittal
view of the eye, a transverse view of the eye, or an anterior view of the eye,
and combinations
thereof. The one or more images of the eye may comprise a tomography image
showing a plane
of the eye and an anterior camera view of the eye, and the one or more optical
structures can be
placed on the one or more images to provide one or more reference locations to
the user. In
many embodiments, the one or more images comprise real time images provided
for the user to
plan and verify eye incisions.
[0095] The optical structure of the eye may comprise one or more
structures of the eye
related to optics of the eye, and the tissue structure of the eye may comprise
one or more tissues
of the eye. The optical structure of the eye may comprise one or more of an
optical axis of the
eye, a visual axis of the eye, a line of sight of the eye, a pupillary axis of
the eye, a fixation axis
of the eye, a vertex of the cornea, an anterior nodal point of the eye, a
posterior nodal point of the
eye, an anterior principal point of the eye, a posterior principal point of
the eye, a keratometry
axis, a center of curvature of the anterior corneal surface, a center of
curvature of the posterior
corneal surface, a center of curvature of the anterior lens capsule, a center
of curvature of the
posterior lens capsule, a center of the pupil, a center of the iris, a center
of the entrance pupil, or
a center of the exit pupil of the eye. The one or more tissue structures may
comprise one or more
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of the iris, a plane of the iris, an outer boundary of the iris, the limbus, a
center of the limbus,
scleral blood vessels, a center of the cornea, a thickness profile of the
cornea, a center of
curvature of a thickness profile of the cornea, a tissue stained with a dye
such as an ink, the
vertex of the cornea, the optical axis of the eye, a center of curvature of
the anterior surface of
the cornea, a center of curvature of the anterior lens capsule, and a center
of curvature of the
posterior lens capsule.
[0096]
Some embodiments provide methods of imaging a cornea or a lens of an eye
using the laser surgery system 10. The methods may include the step of
generating a first
electromagnetic radiation beam using a beam source and passing the first
electromagnetic
radiation beam through a wave plate. The first electromagnetic radiation beam
may be
propagated to a beam scanner. The first electromagnetic radiation beam may be
focused to a
focal point at a location in the cornea of the eye using the beam scanner. A
first reflected
electromagnetic radiation from the focal point may be received after focusing
the first
electromagnetic radiation beam. The first received electromagnetic radiation
may be directed
through the wave plate and towards a sensor. A first intensity signal may be
generated that is
indicative of an intensity of the first received electromagnetic radiation.
Thereafter, the wave
plate may be rotated at an angle after generating the first intensity signal.
A second
electromagnetic radiation beam may be passed through the rotated wave plate
and focused to a
focal point at the location in the cornea of the eye. A second reflected
electromagnetic radiation
from the focal point may be received in response to the step of focusing the
second
electromagnetic radiation beam. The second received electromagnetic radiation
may be directed
through the rotated wave plate and toward the sensor. A second intensity
signal may be
generated that is indicative of an intensity of the second received
electromagnetic radiation. The
anterior surface of the cornea may be identified using the first intensity
signal and at least some
portions of the posterior surface of the cornea may be identified using the
second intensity signal.
A similar approach utilizing multiple wave plate angles is used for imaging
the anterior surface
of the lens with high contrast.
[0097]
The laser surgery system 10 may include a variable axis polarization system
positioned along the beam path between the laser beam source and the eye. The
polarization
system may be configured to polarize an outputted beam with a first
polarization state or a
second polarization state. The polarization system may set the polarization
state of an outputted
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beam when in a first configuration, and may set another polarization state
when in a second
configuration.
[0098] In some embodiments, the wave plate may be further positioned
and configured to
receive reflected electromagnetic radiation from the focal point before the
reflected
.. electromagnetic radiation reaches the sensor. Optionally, the laser surgery
system 10 may
further include a polarizing beam-splitter positioned to direct the reflected
electromagnetic
radiation that passed through the wave plate to the sensor. An aperture may be
positioned to
block reflected electromagnetic radiation from eye locations other than the
location of the focal
point of the outputted beam.
[0099] In some embodiments, the wave plate may be rotatable between the
first position
and the second position. The wave plate may rotate forty-five degrees between
the first position
and the second position. Optionally, the wave plate may rotate ninety degrees
between the first
position and the second position. The beam scanner may include an XY-scan
device and a Z-
scan device. The XY-scan device may be configured to deflect the outputted
beam in two
dimensions transverse to a propagation of outputted beam. The Z-scan device
may be
configured to vary a convergence angle of the beam.
[00100] FIG. 2 schematically illustrates details of an embodiment of
the laser surgery
system 10. Specifically, example configurations are schematically illustrated
for the laser
assembly 12, the confocal detection assembly 14, and the scanning assembly 18.
As shown in
the illustrated embodiment, the laser assembly 12 may include an ultrafast
(UF) laser 32 (e.g., a
femtosecond laser), alignment mirrors 34, 36, a beam expander 38, a one-half
wave plate 40, a
polarizer and beam dump device 42, output pickoffs and monitors 44, and a
system-controlled
shutter 46. The electromagnetic radiation beam 28 output by the laser 32 may
be deflected by
the alignment mirrors 34, 36. In many embodiments, the alignment mirrors 34,
36 may be
adjustable in position and/or orientation so as to provide the ability to
align the beam 28 with the
downstream optical path through the downstream optical components. Next, the
beam 28 may
pass through the beam expander 38, which can increase the diameter of the beam
28. The
expanded beam 28 may then pass through the one-half wave plate 40 before
passing through the
polarizer 42. The beam exiting the polarizer 42 may be linearly polarized. The
one-half wave
plate 40 can rotate this polarization. The amount of light passing through the
polarizer 42
depends on the angle of the rotation of the linear polarization. Therefore,
the one-half wave plate
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40 with the polarizer 42 may act as an attenuator of the beam 28. The light
rejected from this
attenuation may be directed into the beam dump. Next, the attenuated beam 28
may pass
through the output pickoffs and monitors 44 and then through the system-
controlled shutter 46.
By locating the system-controlled shutter 46 downstream of the output pickoffs
and monitors 44,
the power of the beam 28 can be checked before opening the system-controlled
shutter 46.
[00101] As shown in the illustrated embodiment, the confocal detection
assembly 14 can
include a polarization-sensitive device such as a polarized or a non-polarized
beam-splitter 48, a
filter 50, a focusing lens 51, a pinhole aperture 52, and a detection sensor
54. A one-quarter
wave plate 56 may be disposed downstream of the polarized beam-splitter 48.
The beam 28 as
received from the laser assembly 12 may be polarized so as to pass through the
polarized beam-
splitter 48. Next, the beam 28 may pass through the one-quarter wave plate 56,
thereby rotating
the polarization axis of the beam 28. A preferred rotation amount may be a
quarter rotation.
After reflecting from a focal point in the patient's eye, a returning
reflected portion of the beam
28 may pass back through the one-quarter wave plate 56, thereby further
rotating the polarization
axis of the returning reflected portion of the beam 28. After passing back
through the one-
quarter wave plate 56, the returning reflected portion of the beam may
experience a total
polarization rotation of 90 degrees so that the reflected light from the eye
may be fully reflected
by the polarized beam-splitter 48. A birefringence of the cornea can also be
taken into account
if, for example, the imaged structure is the crystalline lens. In this case,
the plate 56 can be
adjusted and/or configured such that the double pass of the plate 56 as well
as the double pass of
the cornea sum up to a polarization rotation of 90 degrees. In some
embodiments, birefringence
of the cornea may be taken into account during imaging of the cornea, as
discussed further below
with regard to FIG. 7A. Because the birefringence of the cornea may be
different from patient
to patient, the configuration/adjustment of the plate 56 can be done
dynamically so as to optimize
.. the signal returning to the detection sensor 54. In some embodiments, the
plate 56 may be
rotated at an angle. Accordingly, the returning reflected portion of the beam
28 may be polarized
to be at least partially reflected by the polarized beam-splitter 48 so as to
be directed through the
filter 50, through the lens 51, and to the pinhole aperture 52. The filter 50
can be configured to
block wavelengths other than the wavelengths of interest. The pinhole aperture
52 may block
.. any returning reflected portion of the beam 28 reflected from locations
other than the focal point
from reaching the detection sensor 54. Because the amount of returning
reflected portion of the
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beam 28 that reaches the detection sensor 54 depends upon the nature of the
tissue at the focal
point of the beam 28, the signal generated by the detection sensor 54 can be
processed in
combination with data regarding the associated locations of the focal point so
as to generate
image/location data for structures of the eye.
[00102] As shown in the illustrated embodiment, the scanning assembly 18
may include a
Z-scan device 58 and an XY-scan device 60. The Z-scan device 58 may be
operable to vary a
convergence/divergence angle of the beam 28 and thereby change a location of
the focal point in
the direction of propagation of the beam 28. For example, the Z- scan device
58 may include one
or more lenses that are controllably movable in the direction of propagation
of the beam 28 to
vary a convergence/divergence angle of the beam 28. The XY-scan device 60 may
be operable
to deflect the beam 28 in two dimensions transverse to the direction of
propagation of the beam
28. For example, the XY-scan device 60 can include one or more mirrors that
are controllably
deflectable to scan the beam 28 in two dimensions transverse to the direction
of propagation of
the beam 28. Accordingly, the combination of the Z- scan device 58 and the XY-
scan device 60
can be operated to controllably scan the focal point in three dimensions, for
example, within the
eye of the patient.
[00103] As shown further in the illustrated embodiment, a camera 62
and associated video
illumination 64 can be integrated with the scanning assembly 18. The camera 62
and the beam
28 may share a common optical path through the objective lens assembly 20 to
the eye. A video
dichroic 66 may be used to combine/separate the beam 28 with/from the
illumination
wavelengths used by the camera. For example, the beam 28 can have a wavelength
of about 355
nm and the video illumination 64 can be configured to emit illumination having
wavelengths
greater than 450 nm. Accordingly, the video dichroic 66 can be configured to
reflect the 355 nm
wavelength while transmitting wavelengths greater than 450 nm.
[00104] FIG. 3 is a simplified block diagram of acts of a process 200 of
the laser surgery
system 10 according to many embodiments for imaging an eye. The laser surgery
system 10
uses a beam source to generate an electromagnetic radiation beam (Action Block
202). The laser
surgery system 10 propagates the electromagnetic radiation beam from the beam
source to a
scanner along a variable optical path having an optical path length that
changes in response to
movement of the eye (Action Block 204). The laser surgery system 10 focuses
the
electromagnetic radiation beam to a focal point at a location within the eye
(Action Block 206).
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A scanner of the laser surgery system 10 scans the focal point to different
locations within the
eye (Action Block 208). The laser surgery system 10 propagates a portion of
the electromagnetic
radiation beam reflected from the focal point location back along the variable
optical path to a
sensor (Action Block 210). The sensor generates an intensity signal indicative
of the intensity of
a portion of the electromagnetic radiation beam reflected from the focal point
location and
propagated to the sensor (Action Block 212).
[00105] FIGS. 4, 5, and 6 illustrates options that may be accomplished
as part of the
process 200. For example, the laser surgery system 10 may include a first
support assembly for
supporting the scanner to accommodate movement of the eye (Action Block 214).
The laser
surgery system 10 may also use a second support assembly to further support
the first support
assembly to accommodate movement of the eye (Action Block 216). The first
support assembly
supports a first reflector configured to reflect the electromagnetic radiation
beam so as to
propagate to the scanner along a portion of the variable optical path (Action
Block 218). A base
assembly supports the second support assembly to accommodate movement of the
eye (Action
Block 220). The second support assembly may support a second reflector
configured to reflect
the electromagnetic radiation beam to propagate along a portion of the
variable optical path so as
to be incident on the first reflector (Action Block 222). The sensor generates
the intensity signal
by passing a reflected portion of the electromagnetic radiation beam through
an aperture to block
portions of the electromagnetic radiation beam reflected from locations other
than the focal point
location (Action Block 224). The electromagnetic radiation beam passes through
a
polarization-sensitive device (Action Block 226) which modifies the
polarization of at least one
of the electromagnetic radiation beam and a portion of the electromagnetic
radiation beam
reflected from the focal point location (Action Block 228). The polarization-
sensitive device
reflects a portion of the electromagnetic radiation beam reflected from the
focal point location so
as to be incident upon the sensor (Action Block 230).
[00106] FIG. 7A shows a process 100 of a laser surgery system for
imaging a cornea of an
eye according to some embodiments of the invention. In some situations, it may
be desirable to
accurately image the cornea with a confocal detector. Further, it may be
desirable to accurately
identify or detect the anterior and posterior boundaries of the cornea, for
example, to determine a
thickness of the cornea. The intensity of a confocal signal may change
substantially between the
front of the cornea and the back of the cornea, which can make detection more
difficult than
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would be ideal. This change in intensity may be related to local changes in
birefringence of the
cornea, which may cause signal loss at a confocal detector. Additionally, in
at least some eyes,
the birefringence properties of the cornea may vary with corneal depth.
Further, corneal
birefringence properties may vary laterally and radially in unpredictable
amounts. Thus, in some
embodiments, the light passing back through the one-quarter wave plate may be
rotated by an
angle other than ninety degrees on the second pass through a polarizing beam-
splitter, such that
some of the light is reflected toward the light source instead of toward the
sensor. The process
100 provided in FIG. 7A may address some of the difficulties of imaging the
back surface of the
cornea. Process 100 may start (Action Block 102) with a variable 0 equal to
zero. The variable
0 may represent a rotation angle of the wave plate relative to an initial
position of the wave plate.
Accordingly, the wave plate may be at an initial position at the start (Action
Block 102) of
process 100. The laser surgery system generates an electromagnetic radiation
beam using a
beam source, e.g., laser 32 (Action Block 104). The electromagnetic beam is
polarized (Action
Block 106) with an initial polarization. The electromagnetic radiation beam
passes through a
polarization-sensitive device (Action Block 108) and through the wave plate
(Action Block 110).
The electromagnetic radiation beam may be focused to a focal point at a
location within the eye
(Action Block 114), and may scan the focal point to a plurality of different
locations within the
eye (Action Block 116). In response to focusing the electromagnetic radiation
beam and/or
scanning the focal point of the electromagnetic radiation, electromagnetic
radiation may be
reflected from the focal point and received by the laser surgery system
(Action Block 118). The
received reflected electromagnetic radiation may be passed through the wave
plate (Action Block
120), and further reflected by the polarization-sensitive device toward a
sensor (Action Block
122). Portions of electromagnetic radiation reflected from locations other
than the focal point
location may be blocked (Action Block 124), for example, by an aperture. An
intensity signal
indicative of the intensity of the received reflected electromagnetic
radiation may be generated
by the sensor (Action Block 126). Once the magnitude of angle 0 is greater
than or equal to
ninety degrees (e.g., the wave plate has rotated ninety degrees from the
initial position of the
wave plate) (Decision Block 128), the laser surgery system generates an image
of the eye
(Action Block 129 and End 130). If the magnitude of angle 0 is less than
ninety degrees
(Decision Block 128), variable 0 may be increased by an incremental amount x.
The wave plate
may be mechanically rotated by a rotation angle 0 (Action Block 134).
Thereafter, the laser
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surgery system may loop back and repeat Action Blocks 104-126 with the wave
plate rotated by
an angle 0. Process 100 may end when steps 104-126 are performed with the wave
plate rotated
by ninety degrees from the initial position of the wave plate.
[00107] As should be appreciated, in an embodiment of process 100, the
laser surgery
system 10 scans the eye with focal points of more than one electromagnetic
radiation beam,
where the electromagnetic radiation beams have varying degrees of polarization
due to a varying
wave plate orientation. The plurality of scans, and hence the plurality of
intensity signals, may
help compensate for difficulties in imaging the anterior and posterior surface
of the cornea due to
the birefringence of the cornea. Some intensity signals may include strong
intensity signals from
an anterior portion of a cornea of the eye. Other intensity signals may
include strong intensity
signals from posterior portions of the cornea. In some embodiments, the
plurality of intensity
signals may be used in-part or in whole to form a composite signal to
accurately identify anterior
and posterior details of a cornea, such as the anterior and posterior
surfaces. Accordingly, the
plurality of scans may compensate for imaging signal loss due to local cornea
birefringence
properties.
[00108] In many embodiments, the above methods may be performed by the
laser surgery
system 10 illustrated in FIG. 1 and FIG. 2. For example, laser 32 may be used
to perform step
104. Polarizer and beam dump device 42 may be used to perform step 106. At
step 108, the
electromagnetic radiation beam may pass through the polarized beam-splitter
48. The one-
quarter wave plate 56 may be used to modify the initial polarization of the
electromagnetic
radiation beam to perform step 110. XY-scan device 60 and Z-scan device 58 may
be used to
perform step 114 and step 116. At step 120, the one-quarter wave plate 56 may
be used to
receive and modify a polarization of the reflected electromagnetic radiation.
The polarized
beam-splitter 48 may be used to reflect the reflected electromagnetic
radiation toward a sensor at
step 122. Pinhole aperture 52 may be used to perform step 124 and detector 54
may be used to
perform step 126. In some embodiments, laser surgery system 10 may be
preprogrammed to
perform multiple scans according to method 100.
[00109] Variable x may be any incremental value. In some embodiments,
x may be one,
two, three, five, fifteen, thirty, forty-five, or ninety degrees. In some
situations, it may be
desirable to perform process 100 quickly. Optionally, process 100 may be
completed with two
scans when x is ninety degrees. In such an embodiment, the eye may be scanned
twice with an
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electromagnetic radiation beam focal point. This may be done preferably to
minimize the effects
of inadvertent eye movement relative to the imaging system between or during
sequential scans.
FIG. 7B and FIG. 7C illustrate two exemplary intensity profiles from a cornea
800 generated by
such a process. FIG. 7B shows a generated intensity profile of reflected
electromagnetic
radiation from a cornea 800 when the one-quarter wave plate has an initial
position of forty-five
degrees. As can be seen, the scan in FIG. 7B may include an intensity profile
with higher
intensity at an anterior surface 802 of the cornea 800, but may have lower
intensity toward some
portions of the posterior surface 804 of the cornea 800. The intensity signal
toward the posterior
surface 804 of the cornea 800 may decrease toward the peripheral edge of the
cornea 800. After
the scan illustrated in FIG. 7B, a second scan illustrated in FIG. 7C may be
performed. FIG.
7C shows a generated intensity profile of reflected electromagnetic radiation
from the cornea
800 after the one-quarter wave plate is rotated ninety degrees from the
initial position to one
hundred thirty-five degrees. As can be seen, the scan in FIG. 7C may include
an intensity
profile with lower intensity at an anterior surface 802 of the cornea when the
one-quarter wave
plate is rotated to one hundred thirty five degrees. The scan in FIG. 7C,
however, may include
an intensity profile with higher intensity at portions of the posterior
surface 804 of the cornea
800. In particular, the scan in FIG. 7C may provide an intensity profile with
higher intensity at
the posterior surface of the cornea 800 and near the peripheral edge of the
cornea 800.
Accordingly, the two scans shown in FIGS. 7B and 7C may be used together to
account for local
variations and to more accurately identify both the anterior surface 802 and
the posterior surface
804 of the cornea 800. Optionally, a corneal thickness may be accurately
calculated thereafter.
[00110] The surface profile of a cornea can be measured in one or more
of many ways,
and may comprise one or more of an anterior corneal surface topography
profile, a posterior a
corneal surface topography profile, or a corneal thickness profile as obtained
from the generated
intensity profiles. In many embodiments, the surface profile comprises a
representation of a
three dimensional profile and may comprise an extraction of one or more
parameters from one or
more images, such as an extraction of keratometry values from a corneal
topography system or
tomography system integrated with the surgical laser. The one or more
parameters can be used
to determine a tissue treatment pattern on the eye, such as the angular
location, depth, arc length
and anterior to posterior dimensions of incisions. For instance, the surface
profile can be used to
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determine an axis of treatment of a plurality of arcuate incisions, the
plurality of arcuate incisions
extending along an arc transverse to the axis of treatment.
[00111] In many embodiments, the optical surface of the eye is fit
with one or more with
one or more of a Fourier transform, polynomials, a spherical harmonics, Taylor
polynomials, a
wavelet transform, or Zernike polynomials. The optical tissue surface may
comprise one or
more of the anterior surface of the cornea, the posterior surface of the
cornea, the anterior surface
of the lens capsule, the posterior surface of the lens capsule, an anterior
surface of the lens
cortex, a posterior surface of the lens cortex, an anterior surface of the
lens nucleus, a posterior
surface of the lens nucleus, one or more anterior surfaces of the lens having
a substantially
constant index of refraction, one or more posterior surfaces of the lens
having a substantially
constant index of refraction, the retinal surface, the foveal surface, a
target tissue surface to
correct vision such as a target corneal surface, an anterior surface of an
intraocular lens, or a
posterior surface of an intraocular lens, for example.
[00112] In an embodiment, a cornea 150, as illustrated in FIG. 8, may
have a first region
152 with a first birefringence and a second region 154 with a second
birefringence. Thus, in
imaging the cornea, a first electromagnetic radiation beam may be directed
through the first
region 152 of the cornea 150 to a first location in the eye. The first
electromagnetic radiation
beam may have a first polarization. A second electromagnetic radiation beam
may be directed
through the second region 154 of the cornea 150 to a second location in the
eye. The second
electromagnetic radiation beam may have a second polarization different than
the first
polarization. An image of the eye encompassing the first and second locations
may be generated
using electromagnetic radiation signals reflected from the eye in response to
the steps of
directing the first and second electromagnetic radiation beams. As such, the
laser surgery system
10 may provide a single composite image that uses a plurality of beams with
varying polarization
to account for local differences in corneal birefringence properties.
[00113] FIG. 9 shows another process 400 of the laser surgery system
10 for imaging a
cornea of an eye according to some embodiments of the invention. In some
situations, process
400 may be used to compensate for birefringence of the cornea to accurately
identify its anterior
and posterior boundaries. The laser surgery system 10 generates an
electromagnetic radiation
beam (Action Block 402), which may be polarized with an initial polarization
(Action Block
404). The electromagnetic radiation beam passes through a polarization-
sensitive device (Action
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Block 406) and is elliptically polarized (Action Block 408). The laser system
surgery 10 focuses
the elliptically polarized electromagnetic radiation beam to a focal point at
a location within the
eye (Action Block 412), and scans the focal point to a plurality of different
locations within the
eye (Action Block 414). The laser system surgery 10 receives reflected
electromagnetic
radiation from the focal point (Action Block 416). The received reflected
electromagnetic
radiation passes through the polarizer (Action Block 418) and is reflected or
directed toward a
sensor (Action Block 420). The laser surgery system 10 may block portions of
electromagnetic
radiation reflected from locations other than the focal point location (Action
Block 422). The
laser surgery system 10 may generate an intensity signal that is indicative of
the intensity of the
received reflected electromagnetic radiation.
[00114] In an embodiment of the process 400, the laser surgery system
10 may use
elliptically polarized light to identify and/or image the anterior and
posterior portions of a cornea
because, for example, elliptically polarized light will not produce linearly
polarized light at one
angle on the second pass through the beam-splitter such that the signal will
change with less
depth.
[00115] FIG. 10A and FIG. 10B schematically illustrate a laser surgery
system 11
according to many embodiments. The laser surgery system 10 includes a laser
assembly 12, a
confocal detection assembly 14, confocal bypass assembly 15, a transfer
optical path 17, a
scanning assembly 18, an objective lens assembly 20, and a patient interface
device 22The laser
surgery system 11 includes elements as described in the laser surgery system
10, as shown in
FIG. 2. The confocal bypass assembly 15 generally includes at least one
optical element 19 and
is operable to reversibly divert the optical path of reflected electromagnetic
beam 29 (a portion
of electromagnetic beam 28) around at least one optical element (not shown)
that delivers a
portion of a reflected electromagnetic beam 29 to a sensor in the confocal
detection assembly 14.
By bypassing the optical element of the confocal detection assembly 14, the
imaging system is
inactivated because the reflected light 29 is not diverted to a sensor in the
confocal bypass
assembly 14. In the embodiment shown in FIG. 10A, the confocal bypass assembly
15 is
represented in a state where it is not actively operating to divert the
optical path of
electromagnetic beam 28, and so in FIG. 10A, a portion of reflected
electromagnetic beam 29 is
shown propagating from transfer optical path 16 to the confocal detection
assembly 14, thereby
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rendering the imaging system of the laser surgery system 10 operable. This may
be referred to as
an "imaging mode" of laser surgery system 100.
[00116] When operating according to the embodiment of FIG. 10A, the
electromagnetic
beam is preferably configured so as to not modify tissue. For example, the
electromagnetic
beam can be attenuated or otherwise modified to have an energy level below a
threshold level for
tissue modification. Alternatively, the electromagnetic beam can be configured
to modify tissue
even in the imaging mode.
[00117] In a preferred embodiment of an imaging mode, a portion of the
electromagnetic
beam 28 is reflected by eye tissue at the focal point and propagates along the
optical bath back to
the confocal detection assembly 14. Specifically, a reflected portion 29 of
the electromagnetic
beam 28 travels back through the patient interface device 22, back through the
objective lens
assembly 20, back through (and de-scanned by) the scanning assembly 15, back
through the
transfer optical path 15, and to the confocal detection assembly 14. In many
embodiments, and
as will be discussed further herein, the reflected portion 29 of the
electromagnetic beam 28 that
travels back to the confocal detection assembly confocal detection assembly is
directed to be
incident upon a sensor that generates an intensity signal indicative of
intensity of the incident
portion of the electromagnetic beam. The intensity signal, coupled with
associated scanning of
the focal point within the eye, can be processed in conjunction with the
parameters of the
scanning to, for example, image/locate structures of the eye, such as the
anterior surface of the
cornea, the posterior surface of the cornea, the iris, the anterior surface of
the lens capsule, and
the posterior surface of the lens capsule.
[00118] Transfer optical path 17 generally comprises one or more
optical elements that
guide beam 28 from the confocal detection assembly 14 or the confocal bypass
assembly 15 to
the scanning assembly 18. It should be noted that while transfer optical path
17 is shown as a
separate component of the laser surgical system 10 of FIG. 1A, the transfer
optical path 17 is
optional. In other embodiments transfer optical path 17 may serve a variety of
other function.
For example, in another embodiment, transfer optical path 17 may comprise or
be substituted by
a free-floating mechanism 16 described in connection with the embodiment of
FIG. 2.
[00119] FIG. 10B schematically illustrates the laser surgery system 11
of FIG. 1A when
the confocal bypass assembly 15 is placed in the optical path of
electromagnetic beam 28. In
FIG. 10B, the confocal bypass assembly 15 is operable to reversibly divert the
optical path of
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electromagnetic beam 28 along an alternative optical path (i.e., a diversion
optical path) that
diverts the beam 28 around at least an optical element (not shown) of the
confocal detection
assembly 14 such that a reflected portion of electromagnetic beam 28 is not
diverted to a sensor
in the confocal detection assembly 30. In the embodiment of FIG. 10B, the
confocal bypass
assembly 15 is represented in a state where it is actively operating to divert
the optical path of
electromagnetic beam 28, and so in FIG. 10B, the electromagnetic beam 28 is
shown
propagating from laser assembly 20 along an optical path through the confocal
bypass assembly
and around the optical element (not shown) of the confocal bypass assembly 14
such that no
portion of electromagnetic beam 28 is directed to a sensor (detector) of the
confocal detection
10 assembly 14. This may be referred to herein as a "non-imaging mode" or
alternatively, as a
"treatment mode" of laser surgery system 10.
[00120] In many embodiments of the treatment mode of FIG. 10B, the beam
28 emitted by
the laser assembly 20 propagates along a fixed optical path through the
confocal bypass
assembly 15 to the transfer optical path 17. Upon reaching the transfer
optical path 17, the beam
15 28 propagates through the remaining laser surgical system in a manner
that is the same or similar
to the embodiment of FIG. 10A. Specifically, beam 28 travels along transfer
optical path 17, is
delivered in turn to the scanning assembly 18 and propagates through the
objective lens assembly
20, through the interface device 22, and to the patient 24 as described with
respect to FIG. 10A.
[00121] It should be noted that, in the embodiment of FIG. 10B, a
portion of the
electromagnetic beam 28 may be reflected by patient tissue at the focal point
and propagate
along the optical path back along the optical path by which it was delivered.
Specifically, a
reflected portion of the electromagnetic beam 28 travels back through the
patient interface device
22, back through the objective lens assembly 20, back through (and de-scanned
by) the scanning
assembly 18, and back through the transfer optical path 17. However, the
reflected beam enters
the confocal bypass assembly 15, which again diverts the optical path of
electromagnetic beam
28 around the at least one optical element of the confocal detection assembly
14 along the
diversion optical path such that the reflected light is not detected by the
confocal detection
assembly 14.
[00122] When operating in the treatment mode, the direction and
position of beam 28 is
preferably the same or substantially the same at the entry of and at the exit
from the diversion
optical path, in a plane transverse to the direction of propagation of the
electromagnetic beam.
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The direction and position of beam 28 is deemed substantially the same at the
entry of and at the
exit from the diversion optical path in a plane transverse to the direction of
propagation of the
electromagnetic beam so long as the beam properties are sufficient to meet the
system level
targeting specification.
[00123] Further, the direction and position of beam 28 at the exit from the
diversion
optical path of confocal bypass assembly 14 in the treatment mode is the same
or substantially
the same as the direction and position of beam 28 at the same position in the
optical path in
imaging mode in a plane transverse to the direction of propagation of the
electromagnetic beams
28.
[00124] When operating in a treatment mode, the electromagnetic beam 28 is
preferably
configured so as to be capable of modifying tissue. For example, the
electromagnetic beam
preferably has an energy level above a threshold level for tissue
modification.
[00125] FIG. 11 is a simplified block diagram of acts of a process 500
according to a
method of imaging an eye in accordance with an imaging mode. Any suitable
device, assembly,
and/or system, such as described herein, can be used to practice the process
500. The process
500 includes using a beam source to generate an electromagnetic beam (Action
Block 502) and
propagating the electromagnetic beam from the beam source to a scanner along
an optical path
comprising at least one optical element of a confocal imaging assembly (Action
Block 504). The
process 500 includes focusing the electromagnetic beam to a focal point at a
location within the
eye (Action Block 506). The process 500 includes using the scanner to scan the
focal point to
different locations within the eye (Action Block 508). The process 500
includes propagating a
portion of the electromagnetic beam reflected from the focal point location
back along the optical
path to the at least one optical element, which diverts the reflected
electromagnetic radiation to a
sensor (Action Block 510). The process 500 includes using the sensor to
generate an intensity
signal indicative of the intensity of the reflected electromagnetic beam from
the focal point
location and propagated to the sensor (step 512).
[00126] FIG. 12 is a process 501 for reversibly switching operation
from an imaging mode
to a non-imaging mode may include using a laser source to generate an
electromagnetic beam
(Action Block 502), propagating the electromagnetic beam from the beam source
along an
optical path comprising at least one optical element of a confocal imaging
assembly (Action
Block 504), moving a confocal bypass assembly into the optical path thereby
diverting the
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electromagnetic beam around the at least one element of the confocal imaging
assembly (Action
Block 514), propagating the diverted electromagnetic radiation to a scanner
(Action Block 516),
using the scanner to scan the focal point to different locations with the eye
(Action Block 518)
and, preventing any portion of the electromagnetic beam reflected from the
focal point location
from being diverted by the at least one optical element to a sensor of the
confocal bypass
assembly (Action Block 520) and moving the confocal bypass assembly out of the
optical path
(Action Block 522).
[00127] One embodiment of a confocal bypass assembly 700 is shown in
FIG. 13. The
confocal bypass assembly 700 includes a push solenoid 710 having an arm 715
that is fixably
connected to one end of actuation arm 720 and is secured in place by a tip
716. In the
embodiment of FIG. 5, push solenoid 710 is held in a frame 417, which is
fixably mounted to
base 750. Arm 715 of the push solenoid reversibly moves in the "A" direction.
The other end of
actuation arm 720 is connected to a carrier 725, which has a platform 735 on
which the bypass
optical element 730 is mounted. The confocal bypass assembly 700 may also
include a slide
member 745 having 2 sides that move relative to teach other along the "A"
direction. In the
embodiment of FIG. 5, the carrier 725 is fixably connected to one side of
slide 745, and frame
717 holding push solenoid 710 is fixably connected the other side of slide 745
such that the push
solenoid and the carrier move in the direction "A" relative to each other.
[00128] In operation, in the embodiment of FIG. 5, arm 715 of push
solenoid 410 moves
in the direction "A" away from the body of the push solenoid, and the movement
of the arm 715
is communicated to the carrier 725 via actuation arm 720 and results in the
movement of carrier
725 in the same "A" direction relative to the body of the push solenoid by
action of the slide 745.
In this way, the bypass optical element 730 is raised into the optical path of
the electromagnetic
path of the electromagnetic beam. The bypass optical element 730 may then be
removed from
the optical path by moving the arm 715 of the push solenoid 710, under control
of control
electronics towards the body of the push solenoid 710, thus reversing the
movement of bypass
optical element 735 and thus moving it out of the optical path of the beam 28.
[00129] The confocal bypass assembly is preferably configured to maximize the
safety of the
laser surgical system, including the laser light incident upon the eye when
the system is in a
predetermined state. This predetermined state may be prior to treatment of the
eye of the patient,
after completion of treatment of the eye the patient or during a loss or
reduction of power to one
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or more system components, such as the confocal bypass assembly. In many
embodiments, the
safety may be increased by insuring the laser surgical system is in a state
where any
electromagnetic beam incident upon the eye is in an attenuated state. Thus, in
a preferred
embodiment, the confocal bypass assembly is configured to return to a position
in an optical path
having a lowest radiant energy incident upon a patient's eye in a situation
where the confocal
bypass assembly is in the predetermined state, such as when then confocal
bypass assembly is
depowered or unexpectedly suffers a loss of power. In many embodiments, an
imaging mode of
the present invention comprises a confocal imaging assembly in which an
electromagnetic beam
passes through a beam-splitter and is then delivered to the scanner and
objective, which focuses
the light on the target tissue, for example, the target eye tissue. The
provision of the optical
beam-splitter in the confocal imaging mode preferably results in the
transmission of only a
fraction of the electromagnetic beam to the target. The use of the optical
beam splitter therefore
makes it possible to attenuate the electromagnetic beam before it is incident
on the target tissue.
Further, in many embodiments, the confocal bypass assembly, when inserted into
the optical path
of the electromagnetic beam, diverts the beam around at least one optical
element of the confocal
detection assembly, typically the beam splitter. As a result, the
electromagnetic beam is
attenuated when in imaging mode relative to the electromagnetic beam when it
is diverted by the
confocal bypass assembly. In many embodiments, the present invention is
preferably an imaging
mode having an attenuated electromagnetic beam relative to the non-imaging
(i.e. treatment
mode) in a predetermined state, such as before initiation of treatment, after
completion of
treatment or during a loss of power to one or more system components.
[00130] As such, in the case where insertion of the confocal bypass optical
elements into the
optical path of the electromagnetic beam results in a higher energy beam
incident upon the eye
(typically, a treatment mode), the confocal bypass assembly is preferably
configure to
automatically exit the optical path upon a predetermined condition, such as
the loss of power to
one or more components. Here, exiting the optical path refers to automatically
moving the
bypass assembly such that the confocal bypass elements are not in optical path
of the
electromagnetic beam (typically, an imaging mode). In such a manner, the
attenuated energy
beam is therefore the default beam incident upon the target tissue. Thus, for
example, in the
embodiment of FIG. 5, arm 715 of push solenoid 410, in a default or depowered
state, is in a
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position such that the bypass optical element is not within the optical path
of the electromagnetic
beam during loss of power to one or more components.
[00131] When treatment is desired to be initiated, the system preferably
requires an affirmative
control by the controller so as to activate arm 715 to push solenoid 410 to
move in the direction
"A" away from the body of the push solenoid. The movement of the arm 715 is
communicated
to the carrier 725 via actuation arm 720 and results in the movement of
carrier 725 in the same
"A" direction relative to the body of the push solenoid by action of the slide
745. In this way, the
bypass optical element 730 is raised into the optical path of the
electromagnetic path of the
electromagnetic beam.
[00132] Preferably, the confocal bypass assembly is automoatically positioned
such that the
attenuated beam is incident upon the at system start up and/or completion of
treatment and/or
sudden or unexpected loss of power. This may be accomplished under the control
of the
controller and also, preferably, mechanically, when, for instance there is a
loss of system power.
In one embodiment, the combined weight of the elements displaced by arm 715 of
push solenoid
710 in the "A" direction is sufficient, when power is interrupted or lost, to
cause the movement
of the bypass optical element 730 out of the optical path of the
electromagnetic path of the
electromagnetic beam. The movement of the bypass optical element out of
optical path of the
electromagnetic beam preferably causes the electromagnetic beam to be incident
upon a beam
splitter which attenuates the electromagnetic beam relative to the
electromagnetic beam incident
upon the eye when the bypass optical element is inserted into the optical path
of the
electromagnetic beam. The weight displaced by the arm 715 of the push solenoid
typically
would include a bypass optical element 730 and a carrier 725 and those of
ordinary skill can
select an appropriate push solenoid accordingly so that the weight of these
elements causes the
optical bypass element to move out of the optical path upon a loss of power.
[00133] The confocal bypass assembly generally includes one or more optical
elements,
referred to herein as bypass optical element optical elements, which, when
inserted into the
optical path of the electromagnetic beam, divert the beam around at least one
optical element of
the confocal detection assembly. The confocal bypass assembly thus establishes
an alternative
optical path, referred to herein as a diversion optical path, around the one
or more optical
elements of the confocal detection assembly. The confocal bypass assembly
should thus be
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configured to reversibly move one or more bypass optical elements into and out
of the optical
path of the electromagnetic beam under control of system control electronics
when an imaging
mode or treatment mode is desired. Those of ordinary skill in the art will
recognize that the
reversible movement of an optical elements into and out of an optical path
thus may be
accomplished in numerous ways.
[00134] In a preferred embodiment, the bypass optical element is a
bypass prism designed
to divert beam 28 around an optical element of the confocal detection assembly
by a series of
reflections within the bypass prism. In one embodiment, the bypass prism is
comprised of two
rhomboid prisms, which may optionally be joined together to form a single
integrated unit.
Alternatively, a set of mirrors can be used to divert the beam around the
optical element of the
confocal detection assembly.
[00135] FIGS. 14A and 14B show certain aspects of a laser surgical
system showing the
operation of a confocal bypass assembly comprising a bypass prism as the
bypass optical
element. In FIG. 14A, the bypass element is below the optical beam 28 and is
shown in dashed
lines to demonstrate its relative position to the confocal detection assembly
when viewed from
above. Since the confocal bypass assembly is not in the optical path in FIG.
14A, FIG. 14A
shows a mode of the system wherein imaging is enabled. In FIG. 14A,
electromagnetic beam 28
passes through a beam-splitter (BS) 305 and is then delivered to the scanner
and objective which
focuses the light on the target tissue (not shown). Returned scattered light
29 from the target
tissue is again directed through a beam-splitter 305 and is directed to a
focusing lens 310, a
pinhole aperture 315 and a sensor (photodetector) 320.
[00136] Preferably, the beam-splitter 305 is configured to attenuate
the beam 28 such that
the beam-splitter 305 transmits only a fraction of the electromagnetic beam 28
to the target
resulting in a high power rejected beam 31 directed to dump 301 as the
remainder of
electromagnetic beam 28 propagates from the light source to the scanner.
Preferably, the beam-
splitter transmits less than 20% of the incident light, more preferably less
than 10%, more
preferably less than 5% and more preferably 1% or less of the incident light.
Further, the beam-
splitter 310 is configured to have a high reflectivity of the returned
scattered light 29 directed to
the sensor 320. Preferably, the beam-splitter reflects 80% of the reflected
light, more preferably
90% of the reflected light, more preferably 95% of the reflected light, and
more preferably, 99%
or more of the reflected light. Thus, in the imaging mode of FIG. 14A, beam 28
exiting the
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beam-splitter 305 is attenuated and optimized for imaging. Beam 28 exiting the
beam-splitter
305 need not be sufficient to modify the target tissue, and in a preferred
embodiment beam 28 is
not configured to modify the target tissue as it exits beam-splitter 305 and
propagates toward the
target tissue.
[00137] In many embodiments, the imaging mode is the default mode of the
system at start up,
and the laser surgical system automatically returns to imaging mode at the
completion of the
treatment or upon loss of power to one or more parts of the system, including,
but not limited to
the optical bypass assembly. The automatic return of the system to the imaging
mode may be
done under the control of the controller or mechanically.
[00138] Preferably, beam-splitter 305 is fixed in the optical path of beam
28 and is not a
polarizing beam-splitter (i.e., it does not operate to split a beam based on a
polarization property
of the reflected light). More preferably, beam-splitter 305 is beam-splitter
prism.
[00139] FIG. 14B shows a bypass prism 302 inserted into the optical
path adjacent the
beam-splitter 305. When the bypass prism 302 is inserted in the optical path
of beam 28, as
shown in FIG. 14B, the beam 28 enters the diversion optical path at point C
and is directed
around the beam-splitter by bypass prism 302 by undergoing a series of
reflections within the
body of bypass prism 302 that form the diversion optical path before exiting
the bypass prism at
point B. The precise number of reflections needed to establish the optical
path is not necessarily
limited; however, the total number of reflections should be an even number so
that the position,
direction and orientation of the beam 28 remain the same at the point it
enters the bypass optical
path (point C in FIG. 14B) and the point it exits the optical path (Point B in
FIG. 14B). In FIG.
14B, a series of 4 reflections are shown and each reflection angle is
represented as being at right
angles, but, while preferred, neither of these is required. Those of ordinary
skill will recognize
that the diversion optical path may be constructed with various optical
elements to achieve an
even number of reflections along the diversion optical path using various
reflection angles.
[00140] Preferably, the direction and orientation of electromagnetic
beam 28 remain the
same or substantially the same at the point it exits the bypass optical path
(point B in FIG. 14B),
and the same position in the optical path of the imaging mode (Point B in FIG.
14A).
"Substantially the same" means that the beam properties are sufficient to meet
the system level
targeting specification.
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[00141] Preferably, the bypass prism automatically exits the optical path of
beam 28 upon loss
of power to one or any part of the system.
[00142] By diverting beam 28 around beam-splitter 305, the power
attenuation of the
beam-splitter prism 300 is avoided and the required boresight accuracy
relative to the imaging
light path, and the laser beam is directed toward the microscope objective to
focus on the target.
Preferably, in the treatment mode of FIG. 14B, the electromagnetic beam is
configured to
modify the target tissue.
[00143] One implementation of a system using a bypass prism and a
confocal bypass
assembly is shown in FIG. 15A and FIG. 15B. The system 350 includes control
electronics 325,
a light source 320, an optional attenuator 340, a beam expander 335, an
optional optical variable
beam attenuator 340, a separate focus lens combination 345 and a scanning
means 350. The light
beam 328 of light source 320 is propagated though beam-splitter and is focused
through lens 360
to its target location 375. Additionally, the reflected light from the target
structure 375 is again
directed through the beam-splitter 305 and diverted to lens 310. An aperture
pinhole 315 is
placed in the focal spot of reflected beam as a conjugate of the laser beam
focus in target
structure 375. The intensity of the reflected electromagnetic beam through
beam aperture 315 is
detected and converted to an electrical signal which can be read by the
control unit 325. In the
embodiment of FIG. 15A and FIG. 15B, an image of the treated area is imaged by
lens 365 on
an image capture device 370 which can be a CCD or a CMOS camera. Also this
signal is
transmitted to control unit 325.
[00144] FIG. 16 illustrates a laser surgery system 1000 used for
imaging and treating an
eye according to another embodiment that includes a bypass assembly. The laser
surgery system
1000 includes elements as described in the laser surgery system 10, as shown
in FIG. 2. The
laser surgery system 1000 further may manage the different power levels
required for imaging at
low levels and treating at high levels and at the same time switching between
imaging and
treatment optical path. At the same time, this should be done in a manner
which makes the
whole assembly insensitive to mechanical design choices. The laser surgery
system 1000 may
further include imaging ocular structures in a low power imaging mode to
determine the location
of reference surfaces and then using this information to treat in a second
high power treatment
mode.
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[00145] In an embodiment, the laser surgery system 1000 does not make
use of a
polarizing element to avoid issues which arise with the polarization rotation
of the cornea. This is
achieved by utilizing a high ratio non-polarizing beam-splitter 1048 to
separate said beams for
imaging. A high splitting ratio of said beam-splitter 1048 acts in two ways:
first, reduction of
incident power to a regimen where it can be utilized for safe imaging; and
second, acting as a
high reflector for the light from imaged structure. A second moveable optical
element 1014 is
inserted in the beam path to bypass the first high contrast beam-splitter 1048
and redirect all
available laser light around said splitter 1048 to enable treatment at high
energy levels. This
bypass element 1014 may have single or multiple prisms or mirrors. The
advantage of using this
embodiment lays in its high tolerance to mechanical variations to the moving
of the bypass
element 1014. One could also just move the high contrast beam-splitter 1048,
but the
mechanical tolerances to enable this would be quite high. All tolerances are
relaxed by an order
of magnitude by utilizing the bypass assembly 1014.
[00146] Regarding the "non-polarizing" performance of the low transmission
beamsplitter, in
many embodiments, the reflection from a transmissive "non-polarized" beam
splitter is generally
non-polarized, but the transmission may be polarized, without effecting our
application. For
example: a 1% non-polarizing beam splitter may reflect 100% of S-polarized
light, and 98% of
P-polarized light. Thus, reflection is 99% of all the light and transmission
in a 1% non-
polarizing beam splitter is 1% of all the light. However, while the reflected
light is only 1%
polarized the transmitted light is 100% polarized, even if only 1% of the
total. When a system is
designed having only P-polarized light in the outgoing direction, it makes no
difference if the
beamsplitter reflects or transmits S-polarized light in the outgoing beam
path. Upon return from
the target tissue, the non-polarized character of the beam splitter makes a
huge difference to the
system performance. This type of low transmission beam splitter is much easier
to make than
one that is fully non-polarizing even to the low percentage of transmitted
light.
[00147] In an embodiment, the laser surgery system 1000 focuses a
first electromagnetic
radiation beam to a focal point at a location in the eye, wherein the first
electromagnetic
radiation beam has a first polarization. The laser surgery system 1000 may
further focus a
second electromagnetic radiation beam to a focal point at the location in the
eye, wherein the
second electromagnetic radiation beam has a second polarization state which is
different from
the first polarization state. The laser surgery system 1000 may further
generate a first intensity
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signal indicative of an intensity of electromagnetic radiation reflected from
the eye in response to
the step of focusing the first electromagnetic radiation beam, and generate a
second intensity
signal indicative of an intensity of electromagnetic radiation reflected from
the eye in response to
the step of focusing the second electromagnetic radiation beam. One or more
images of the eye
may then be generated with the first and second intensity signals.
[00148] In an embodiment, the first and second electromagnetic
radiation beams may be
focused using a beam scanner. The laser surgery system 1000 may further scan
the focal point of
the first electromagnetic radiation beam to a plurality of different locations
in a first region of the
eye and may scan the focal point of the second electromagnetic radiation beam
to the plurality of
different locations in a second region of the eye. A first intensity profile
may be generated that is
indicative of intensities of electromagnetic radiation reflected from the eye
in response to the
step of scanning the focal point of the first electromagnetic radiation beam.
A second intensity
profile may be generated that is indicative of intensities of electromagnetic
radiation reflected
from the eye in response to the step of scanning the focal point of the second
electromagnetic
radiation beam. In an embodiment, one image of the eye is generated using the
first and second
intensity profiles. For example, in imaging a cornea of an eye, the anterior
surface of the cornea
may be identified using the first intensity profile and the posterior surface
of the cornea may be
identified using at least a portion of the second intensity profile. In
another embodiment, the first
electromagnetic radiation beam has a first polarization; the second
electromagnetic radiation
beam has a second polarization different than the first polarization.
[00149] A beam scanner may include an XY-scan device 1060 that is
configured to deflect
the first and second electromagnetic radiation beams in two dimensions
transverse to a
propagation of first and second electromagnetic radiation beams. The focal
point of the first and
second electromagnetic radiation beam may be scanned in the two dimensions
using the XY-
scan device 1060 according to some embodiments and may thereby provide an
image with at
least two dimensions.
[00150] The beam scanner may further include a Z-scan device 1058 that
is configured to
vary a convergence depth of the beam within the eye. In some embodiments, the
Z-scan device
1058 may vary a convergence angle of the beam. The focal point of the first
and second
electromagnetic radiation beams may then be scanned in the three dimensions
using the XY-scan
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device 1060 and the Z-scan device 1058. Accordingly, the image of the eye may
be three
dimensional according to some embodiments.
[00151] In an embodiment, the first and second intensity signals may
be generated by a
sensor 1054. The sensor 1054 may be a confocal sensor and the laser surgery
system 1000 may
further block reflected electromagnetic radiation from eye locations other
than the location of the
focal point of the first and second electromagnetic radiation beams from
reaching the sensor
1054.
[00152] In an embodiment, the first electromagnetic radiation beam may
be generated by
passing an electromagnetic radiation beam through a wave plate in a first
position, e.g., wave
plate 56 as shown in FIG. 2, so as to polarize the electromagnetic radiation
beam with the first
polarization. The wave plate may be rotated by an angle to a second position.
The second
electromagnetic radiation beam may be generated by passing the electromagnetic
radiation beam
through the wave plate in the second position. This wave plate may be a one-
quarter wave plate.
In some embodiments, the wave plate may be rotated by an acute angle for
generating the second
electromagnetic radiation beam. In some embodiments, the wave plate may be
rotated ninety
degrees for generating the second electromagnetic radiation beam. In some
embodiments, the
first and second electromagnetic radiation beams may be polarized with the
first and second
polarizations by using a Faraday rotator, or a rotating beam-splitter.
[00153] In response to the step of focusing the first electromagnetic
radiation beam, the
electromagnetic radiation reflected from the eye passes through the wave plate
in the first
position. Further, electromagnetic radiation reflected from the eye in
response to the step of
focusing the second electromagnetic radiation beam may be passed through the
wave plate in the
second position.
[00154] In another embodiment, the laser surgery system 1000 may scan
a focal point of a
first electromagnetic radiation beam to a plurality of locations in the eye,
with the first
electromagnetic radiation beam having a first polarization. The laser surgery
system 1000 may
further scan a focal point of a second electromagnetic radiation beam to at
least a portion of the
plurality of locations in the eye, with the second electromagnetic radiation
beam having a second
polarization different than the first polarization. A first intensity profile
indicative of an intensity
of electromagnetic radiation reflected from the eye may be generated in
response to the step of
scanning the first electromagnetic radiation beam. And a second intensity
profile indicative of
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an intensity of electromagnetic radiation reflected from the eye may be
generated in response to
the step of scanning the second electromagnetic radiation beam. An image of
the eye may be
produced using the first and second intensity profiles.
[00155] FIG. 17 illustrates, according to an embodiment, the bypass
assembly 1014 as
used in a treatment mode. As shown, the electromagnetic radiation beam is
directed toward the
bypass mirrors or prisms of the bypass assembly 1014, and bypasses the beam-
splitter 1048. As
a result, 100% of the electromagnetic radiation beam passes downstream,
providing a high power
level for treatment mode. FIG. 18 illustrates the system 1000 as used in
imaging mode,
according to an embodiment. In this embodiment, the electromagnetic radiation
beam is directed
toward the non-polarized beam-splitter and dump 1048, and bypasses the bypass
assembly 1014.
The non-polarized beam-splitter is a 1/99% beam-splitter. As a result, 99% of
the
electromagnetic radiation beam is directed toward the dump, and 1% of the
electromagnetic
radiation beam passes downstream toward the eye of the patient, resulting in a
low power level
for imaging. After reflecting from a focal point in the eye of the patient, a
returning reflected
portion of the beam is again directed by the beam-splitter. As a result, 99%
of the reflected
portion of the beam is directed upon the sensor 1054 for imaging.
[00156] It should be noted that other embodiments of the bypass
assembly 1014 having
single or multiple mirrors or prisms may be used. For example, FIGS. 19 and 20
illustrate other
embodiments of the bypass assembly 1014 in treatment mode. In FIG. 19, the two
mirrors or
prisms positioned at an angle are further connected with a third prism. In
FIG. 20, the bypass
assembly 1014 utilizes four mirrors or prisms as shown.
[00157] FIG. 21 shows a process 1100 of the laser surgery system 1000
for imaging and
treating an eye, e.g., a cornea, according to an embodiment of the invention.
The laser surgery
system 1000 uses a beam source to generate an electromagnetic radiation beam
(Action Block
1110). If the system 1000 is in treatment mode (Decision Block 1120), the
system 1000
propagates the electromagnetic radiation beam to a bypass assembly 1014
(Action Block 1130).
If the system 1000 is in imaging mode (Decision Block 1120), the system 1000
propagates the
electromagnetic radiation beam to a beam-splitter and dump 1048 (Action Block
1140). It is
noted that the beam- splitter need only be substantially unpolarized in the
returning (i.e. reflected
beam). The outgoing (transmitted beam) may already be inherently polarized and
the beam-
splitter transmission can be either polarization dependent or polarization
independent, so long as
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the correct outgoing beam transmission occurs. In imaging mode, as a portion
of the
electromagnetic radiation beam is reflected from the focal point location in
the eye, the system
1000 propagates a portion of the reflected electromagnetic radiation beam to a
sensor 1054 for
imaging (Action Block 1150).
[00158] Further, while some of the above methods are described as using a
wave plate and
more specifically a one-quarter wave plate, it should be understood that other
variable axis
polarization systems may be used. For example, in some embodiments of
processes 100 and
400, the laser surgery system 10 may use a spatial light modulator (e.g., a
liquid crystal panel),
two or more retarding wave plates, a Faraday rotator, a rotating polarizing
beam-splitter, and so
on.
[00159] In some embodiments, knowledge about corneal polarization may
be used for
other therapeutic applications in which the degree of polarization rotation is
an indicator of tissue
condition, and could lead to iteration of the planned treatment. For instance,
corneal retardance
could be an indicator of disease progression such as corneal thinning, or
could indicate the
strength of corneal tissue, which in turn would be valuable in correctly
calculating corneal
arcuate incisions, or limbal relaxing incisions used for astigmatic
correction.
[00160] In many embodiments, one or more measurements of a cornea are
used with input
parameters to determine locations of incisions of the cornea, such as corneal
incisions. The one
or more measurements can be obtained in many ways, such as with images used
for measuring
corneal topography or tomography, or without imaging the eye. One or more
additional images
can be obtained when the one or more measurements are obtained, and these one
or more
additional images can be used in combination with the measurements for
aligning the
measurement coordinates and the cutting coordinates.
[00161] In many embodiments, a surface profile of the cornea is
measured in one or more
of many ways, and may comprise one or more of an anterior corneal surface
topography profile,
a posterior a corneal surface topography profile, or a corneal thickness
profile. In many
embodiments, the surface profile comprises a representation of a three
dimensional profile and
may comprise an extraction of one or more parameters from one or more images,
such as an
extraction of keratometry values from a corneal topography system or
tomography system
integrated with the surgical laser. The one or more parameters can be used to
determine a tissue
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treatment pattern on the eye, such as the angular location, depth, arc length
and anterior to
posterior dimensions of relaxing incisions.
[00162] FIG. 22 is a simplified process 900 of imaging an eye with a
proposed incision,
according to the many embodiments for imaging an eye described herein. FIGS.
23A-23B show
an exemplary display of an incision review of a cornea of an eye generated
according to an
embodiment of the invention. Although FIGS. 22 and 23A-23B are described using
an arcuate
incision, the laser cut preview images are not limited to arcuate incisions
and can be generated
for primary and side-port incisions, as well as any other incision in the eye.
[00163] The process may start with obtaining an image of the eye as discussed
in any of the
embodiments herein, such as by a laser surgery system 10 (Action Block 902). A
plurality of
parameters are then received that define the laser incision (Action Block
904). For instance, the
parameters of an arcuate incision cut may include the type of cut, axis
(degree), optical zone
(mm), length (mm), center method, horizontal spot spacing (1.tm), vertical
spot spacing (1.tm),
pulse energy (1..0), anterior density, anterior line distance (1.tm), central
line density, uncut anterior
(1.tm), uncut posterior (1.tm), and side cut angle (degree). The type of cut
may include single,
symmetric, asymmetric and toric. The uncut anterior and uncut posterior may
also be input as a
percentage value and indicate a margin of the cut from the cornea anterior and
cornea posterior,
respectively. The parameters may be input or predetermined. FIG. 23A
illustrates an image
1200 of the cornea including the anterior 1204 and posterior 1206. A preview
of an arcuate
incision 1202 is overlaid on the cornea image 1200 where the incision 1202 is
of the same cross-
sectional plane as the cornea image. From FIG. 23A alone, a user is unable to
verify that the
incision does not penetrate the cornea throughout the entire length of the
incision since only one
plane of the incision 1202 is shown.
[00164] Next, a two-dimensional image of the eye is generated in a plane
defined by the
intersection of the length and depth of the cut (Action Block 906). In
particular, the image is in
the plane of the incision axis and an incision length transverse to the
incision axis. The image can
include the cornea anterior and cornea posterior and may include enhancement
to highlight the
cornea anterior and cornea posterior, as shown in FIG. 23B and explained in
further detail
below. Based on the received cut parameters, a three-dimensional
representation of the cut is
generated such as of a conical surface of an arcuate incision (Action Block
908). From the
generated three-dimensional representation of the cut, a three-dimensional
cross-section of the
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conical surface along a length of the cut is determined (Action Block 910).
This "along the cut"
image is defined as a set of points representing a section of the conical
surface including the
arcuate incision. In order to display the three-dimensional cross-section on
the two-dimensional
image of the eye, the "along the cut" image is necessarily distorted, such as
by 3D projection, so
that the points of the three-dimensional surface are mapped onto the two-
dimensional plane of
the image (Action Block 912). Alternatively, the set of points in the three-
dimensional
representation may be set with a common angular value in the conical surface
to be in the same
column of the two-dimensional image in order to overlay the arcuate incision
over the eye. No
matter how the three-dimensional representation is displayed on the two-
dimensional eye image,
the overlaid image is displayed for verification on a display of the system
visible to the user
(Action Block 914). Alternatively, a processor of the system 10 may perform
the verification to
determine if the proposed cut crosses the anterior or posterior of the cornea.
[00165] FIG. 23B is an exemplary display 1250 of the along the cut image
overlaid on the
image of the eye that is displayed to a user. The shaded area 1252 represents
the proposed cut
along the length of the cut. In particular, the cornea anterior 1254 and the
cornea posterior 1256
are highlighted by a solid line and dashed line respectively, for a surgeon to
verify that the
shaded arcuate incision area 1252 does not penetrate the cornea posterior at
any point. The
arcuate incision 1252 is a projection of the three-dimensional surface onto
the two-dimensional
eye image that allows a surgeon to visually determine whether the incision
will penetrate the
posterior surface of the cornea at any point along the cut, instead of just at
a single cross-section.
The "along the cut" images may be generated using confocal imaging that
produces one pixel per
laser pulse or by OCT that produces vertical A scans of pixels for each pulse.
[00166] While the incision preview image of FIG. 23A displays only one plane
of the incision,
the incision preview of FIG. 23B displays the proposed incision along the
entire length of the
cut, thereby allowing a surgeon to more accurately verify whether the proposed
cut will cross
through the cornea at any point along the length of the cut.
[00167] In an embodiment, the laser surgery system 10 receives a plurality of
parameters
corresponding to the treatment planning, generates a three-dimensional
representation of the
treatment planning, maps the three-dimensional representation onto the image
of the eye, and
displays the mapped image for the treatment planning. The treatment planning
includes an
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arcuate incision. The system can verify that the arcuate incision lies within
the cornea. The
received parameters may include a treatment axis and a treatment length
transverse to the axis.
The image of the eye is in a plane of the treatment axis and the treatment
length. The three-
dimensional representation is mapped onto the image of the eye by projecting
the three-
dimensional representation onto a two-dimensional space. The displayed image
comprises a
cornea of the eye including an anterior and posterior. The anterior and
posterior of the cornea
are highlighted. The treatment planning may also include one of a primary and
side-port
incision.
[00168] In an embodiment, the laser surgery system 10 focuses a first
electromagnetic radiation
beam to a focal point at a location in the eye and focuses a second
electromagnetic radiation
beam to a focal point at the location in the eye. A first intensity signal is
generated indicative of
an intensity of electromagnetic radiation reflected from the eye in response
to the step of
focusing the first electromagnetic radiation beam. A second intensity signal
is generated
indicative of an intensity of electromagnetic radiation reflected from the eye
in response to the
step of focusing the second electromagnetic radiation beam. One or more images
of the eye are
generated with the first and second intensity signals for treatment planning.
A plurality of
parameters are received corresponding to the treatment planning. A three-
dimensional
representation of the treatment planning is generated. The three-dimensional
representation is
mapped onto the image of the eye. The mapped image is displayed for the
treatment planning.
[00169] In an embodiment, the laser surgery system includes a laser beam
source configured to
output a beam along a beam path toward the eye. A beam scanner is configured
to direct the
outputted beam to a plurality of locations in the eye. A sensor is positioned
to receive reflected
electromagnetic radiation from the eye. A processor is configured to generate
one or more
images of the eye with the first and second intensity signals for treatment
planning. A user input
device is configured to receive a plurality of parameters corresponding to the
treatment planning.
The processor generates a three-dimensional representation of the treatment
planning, maps the
three-dimensional representation onto the image of the eye. A display is
configured to display
the mapped image for the treatment planning.
[00170] FIGS. 24 and 25 schematically illustrate a laser surgery system 600
and 650,
respectively according to many embodiments. The laser surgery system 600 in
FIG. 24
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includes the laser assembly 12, the confocal detection assembly 14, the free-
floating mechanism
16, the scanning assembly 18, the objective lens assembly 20, the patient
interface 22,
communication paths 302, control electronics 304, control panel/graphical user
interface (GUI)
306, and user interface devices 308. The control electronics 304 includes
processor 310, which
includes memory 312. The patient interface 22 is configured to interface with
a patient 24. The
control electronics 304 is operatively coupled via the communication paths 302
with the laser
assembly 12, the confocal detection assembly 14, the free-floating mechanism
16, the scanning
assembly 18, the control panel/GUI 306, and the user interface devices 308.
The laser surgery
system 650 in FIG. 25 additionally includes the confocal bypass assembly 15,
and substitutes the
transfer optical path 17 for the free floating-mechanism 16. It should be
noted, however, that
free floating assembly 16 could also replace the transfer optical path 17 in
laser surgery system
650.
[00171] The scanning assembly 18 can include a Z-scan device and an XY-scan
device. The
laser surgery system 300 may be configured to focus the electromagnetic
radiation beam 28 to a
focal point that is scanned in three dimensions. The Z-scan device may be
operable to vary the
location of the focal point in the direction of propagation of the beam 28.
The XY-scan device
may be operable to scan the location of the focal point in two dimensions
transverse to the
direction of propagation of the beam 28. Accordingly, the combination of the Z-
scan device and
the XY-scan device can be operated to controllably scan the focal point of the
beam in three
dimensions, including: within a tissue, e.g., eye tissue, of the patient 24.
The scanning assembly
18 may be supported by the free-floating mechanism 16, which may accommodate
patient
movement, induced movement of the scanning assembly 18 relative to the laser
assembly 12 and
the confocal detection assembly 14 in three dimensions.
[00172] The patient interface 22 is coupled to the patient 24 such that the
patient interface 22,
the objective lens assembly 20, and the scanning assembly 18 move in
conjunction with the
patient 24. For example, in many embodiments, the patient interface 22 employs
a suction ring
that is vacuum attached to an eye of the patient 24. The suction ring may be
coupled to the
patient interface 22, for example, using vacuum.
[00173] The control electronics 304 controls the operation of and/or can
receive input from the
laser assembly 12, the confocal detection assembly 14, the free-floating
assembly 16, the
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scanning assembly 18, the patient interface 22, the control panel/GUI 306, and
the user interface
devices 308 via the communication paths 302. The communication paths 302 can
be
implemented in any suitable configuration, including any suitable shared or
dedicated
communication paths between the control electronics 304 and the respective
system components.
[00174] The control electronics 304 can include any suitable components, such
as one or more
processors, one or more field-programmable gate array (FPGA), and one or more
memory
storage devices. In many embodiments, the control electronics 304 controls the
control
panel/GUI 306 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.
[00175] The control electronics 304 can include a processor/controller 310
that is used to
perform calculations related to system operation and provide control signals
to the various
system elements. A computer readable medium 312 is coupled to the processor
310 in order to
store data used by the processor and other system elements. The processor 310
interacts with the
other components of the system as described more fully throughout the present
specification. In
an embodiment, the memory 312 can include a look up table that can be utilized
to control one or
more components of the laser system surgery system 300.
[00176] The processor 310 can be a general purpose microprocessor configured
to execute
instructions and data such as a processor manufactured by the Intel
Corporation of Santa Clara,
California. It can also be an Application Specific Integrated Circuit (ASIC)
that embodies at
least part of the instructions for performing the method according to the
embodiments of the
present disclosure in software, firmware and/or hardware. As an example, such
processors
include dedicated circuitry, ASICs, combinatorial logic, other programmable
processors,
combinations thereof, and the like.
[00177] The memory 312 can be local or distributed as appropriate to the
particular application.
Memory 312 can include a number of memories including a main random access
memory
(RAM) for storage of instructions and data during program execution and a read
only memory
(ROM) in which fixed instructions are stored. Thus, the memory 312 provides
persistent (non-
volatile) storage for program and data files, and may include a hard disk
drive, flash memory, a
floppy disk drive along with associated removable media, a Compact Disk Read
Only Memory
(CD-ROM) drive, an optical drive, removable media cartridges, and other like
storage media.
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[00178] The user interface devices 308 can include any suitable user
input/output device
suitable to provide user input to the control electronics 304. For example,
the user interface
devices 308 can include devices such as a touch-screen display/input device, a
keyboard, a
footswitch, a keypad, a patient interface radio frequency identification
(RFID) reader, an
emergency stop button, a key switch, and so on.
[00179] The embodiments disclosed herein are well suited for
combination with prior
laser surgery systems, such as CatalysTM commercially available from
Optimedica, and similar
systems. Such systems can be modified in accordance with the teachings
disclosed herein and to
more accurately measure and treat the eye.
[00180] Other variations are within the spirit of the present invention.
Thus, while the
invention is susceptible to various modifications and alternative
constructions, certain illustrated
embodiments thereof are shown in the drawings and have been described above in
detail. It
should be understood, however, that there is no intention to limit the
invention to the specific
form or forms disclosed, but on the contrary, the intention is to cover all
modifications,
alternative constructions, and equivalents falling within the spirit and scope
of the invention, as
defined in the appended claims.
[00181] The confocal bypass assembly has been described here in
relation to a specific
laser eye surgery system. The bypass assemblies, such as those illustrated in
FIG. 13, and as
described herein, may be generally applied to other laser surgery systems in
cases where it may
be advantageous to separate an imaging mode from a treatment mode in specified
surgery fields.
They may also be applicable to non-surgical systems and methods, such as
various materials
processing systems, and micromachining systems.
[00182] Other embodiments include and incorporate imaging systems
having laser
assemblies, confocal detection assemblies, and systems that accommodate
patient movement,
including the eye interface, scanning assembly, free-floating mechanism
described in U.S.
Publication No. US 2014-0316389A1 (U.S. Patent Application No. 14/191,095,
filed February
26, 2014 and entitled, "Laser Eye Surgery System,") and U.S. Publication No.
US 2014-
0276671A1 (U.S. Patent Application No. 14/190,827, filed February 26, 2014 and
entitled, "Free
Floating Patient Interface for Laser Surgery System,).
[00183] All patents and patent applications cited herein are hereby
incorporated by
reference in their entirety.
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[00184] The use of the terms "a" and "an" and "the" and similar
referents in the context of
describing the invention (especially in the context of the following claims)
are to be construed to
cover both the singular and the plural, unless otherwise indicated herein or
clearly contradicted
by context. The terms "comprising," "having," "including," and "containing"
are to be construed
as open-ended terms (i.e., meaning "including, but not limited to,") unless
otherwise noted. The
term "connected" is to be construed as partly or wholly contained within,
attached to, or joined
together, even if there is something intervening. Recitation of ranges of
values herein are merely
intended to serve as a shorthand method of referring individually to each
separate value falling
within the range, unless otherwise indicated herein, and each separate value
is incorporated into
the specification as if it were individually recited herein. All methods
described herein can be
performed in any suitable order unless otherwise indicated herein or otherwise
clearly
contradicted by context. The use of any and all examples, or exemplary
language (e.g., "such
as") provided herein, is intended merely to better illuminate embodiments of
the invention and
does not pose a limitation on the scope of the invention unless otherwise
claimed. No language
in the specification should be construed as indicating any non-claimed element
as essential to the
practice of the invention. 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.
[00185] While certain illustrated embodiments of this disclosure have been
shown and
described in an exemplary form with a certain degree of particularity, those
skilled in the art will
understand that the embodiments are provided by way of example only, and that
various
variations can be made without departing from the spirit or scope of the
invention. Thus, it is
intended that this disclosure cover all modifications, alternative
constructions, changes,
substitutions, variations, as well as the combinations and arrangements of
parts, structures, and
steps that come within the spirit and scope of the invention as generally
expressed by the
following claims and their equivalents.
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