U.S. patent number RE40,002 [Application Number 10/626,486] was granted by the patent office on 2008-01-15 for treatment of presbyopia and other eye disorders using a scanning laser system.
This patent grant is currently assigned to SurgiLight, Inc.. Invention is credited to Jui-Teng Lin.
United States Patent |
RE40,002 |
Lin |
January 15, 2008 |
**Please see images for:
( Certificate of Correction ) ** |
Treatment of presbyopia and other eye disorders using a scanning
laser system
Abstract
Presbyopia is treated by a method which uses ablative lasers to
ablate the sclera tissue and increase the accommodation of the
ciliary body. Tissue bleeding is prevented by an ablative laser
having a wavelength of between 0.15 and 3.2 micron. A scanning
system is proposed to perform various patterns on the sclera area
of the cornea to treat presbyopia and to prevent other eye disorder
such as glaucoma. Laser parameters are determined for accurate
sclera expansion. REEXAMINATION RESULTS The questions raised in
reexamination request no. 90/006,090, filed Aug. 22, 2001, have
been considered and the results thereof are reflected in this
reissue patent which constitutes the reexamination certificate
required by 35 U.S.C. 307 as provided in 37 CFR 1.570(e), for ex
parte reexaminations, or the reexamination certificate required by
35 U.S.C. 316 as provided in 37 CFR 1.997(e) for inter partes
reexaminations.
Inventors: |
Lin; Jui-Teng (Coleman,
FL) |
Assignee: |
SurgiLight, Inc. (Orlando,
FL)
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Family
ID: |
22698046 |
Appl.
No.: |
10/626,486 |
Filed: |
July 24, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
09189609 |
Nov 10, 1998 |
06263879 |
Jul 24, 2001 |
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Current U.S.
Class: |
128/898; 606/10;
606/11; 606/4; 606/5; 607/89 |
Current CPC
Class: |
A61F
9/008 (20130101); A61F 9/00808 (20130101); A61F
9/00838 (20130101); A61F 9/00781 (20130101); A61F
2009/00865 (20130101); A61F 2009/00872 (20130101) |
Current International
Class: |
A61B
19/00 (20060101) |
Field of
Search: |
;128/898
;606/3-5,10,11,17,107 ;607/89 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Sher, Surgery for Hyperopia and Presbyopia, Oct. 1997, Williams
& Wilkens, First Edition, 33-36. cited by examiner .
Thornton, Spencer P., Anterior Ciliary Sclerotomy (ACS), A
Procedure to Reverse Presbyopia, in "Surgery for Hyperopia and
Presbyopia", Oct. 1997, pp. 33-36 (chapter 4), published by
Williams & Wilkins. cited by other.
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Primary Examiner: Cohen; Lee S.
Attorney, Agent or Firm: Knobbe, Martens, Olson & Bear
LLP
Claims
I claim:
1. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by
ablating the sclera comprising the steps of: selecting a pulsed
ablation laser having a pulsed output beam of predetermined
wavelength; selecting a beam spot controller mechanism for reducing
and focusing said selected ablative laser's output beam onto a
predetermined spot size on the surface of the .[.cornea.].
.Iadd.eye.Iaddend.; selecting a scanning mechanism for scanning
said ablative laser output beam; coupling said ablative laser beam
to a scanning device for scanning said ablative laser over a
predetermined area of the .[.corneal.]. sclera; and controlling
said scanning mechanism to deliver said ablative laser beam in a
predetermined pattern in said predetermined area onto the surface
of the .[.cornea.]. .Iadd.eye .Iaddend.to photoablate the sclera
tissue outside the limbus .Iadd.to a depth of 80-90% of the
thickness of the scleral tissue.Iaddend., whereby a presbyopic
patient's vision is corrected by expansion of the sclera.
2. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by
ablating the sclera in accordance with claim 1 in which the step of
selecting a pulsed ablation laser includes selecting a pulsed
ablative laser having a predetermined wavelength between 0.15-0.32
microns.
3. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by
ablating the sclera in accordance with claim 1 in which the step of
selecting a pulsed ablation laser includes selecting a pulsed
ablative laser having a wavelength between 2.6 and 3.2 microns.
4. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by
ablating the sclera in accordance with claim 1 in which the step of
selecting a pulsed ablation laser includes selecting a solid state
laser.
5. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by
ablating the sclera in accordance with claim 1 in which the step of
selecting a pulsed ablation laser includes selecting a pulsed gas
laser having a pulse duration shorter than 200 nanoseconds.
6. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by
ablating the sclera in accordance with claim 1 in which .[.said.].
the step of selecting a beam spot controller includes selecting a
pulsed ablative laser having a focusing lens with focal length of
between 10 and 100 cm selected to obtain a predetermined laser beam
spot size having a diameter of between 0.1 and 0.8 mm on the
.[.corneal.]. .Iadd.eye .Iaddend.surface.
7. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by
ablating the sclera in accordance with claim 1 in which the step of
selecting a beam spot controller includes selecting .Iadd.a
.Iaddend.beam spot controller having a focusing lens with cylinder
focal length of between 10 and 100 cm to obtain a laser beam spot
having a line size of about 0.1-0.8 mm.times.3-5 mm on the
.[.corneal.]. .Iadd.eye .Iaddend.surface.
8. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by
ablating the sclera in accordance with claim 1 in which the step of
selecting a scanning mechanism includes selecting a scanning
mechanism having a pair of reflecting mirrors mounted to a
galvanometer scanning mechanism for controlling said laser output
beam into a predetermined pattern.
9. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by an
ablating laser beam in accordance with claim 1 in which said
ablative laser is delivered to the surface of the .[.cornea.].
.Iadd.eye .Iaddend.by an optical fiber.
10. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by
ablating the sclera in accordance with claim 1 in which the step of
selecting a scanning mechanism includes selecting a hand-held
optical fiber coupled to the ablation laser for scanning said laser
output beam into a predetermined pattern.
11. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by
ablating the sclera in accordance with claim 1 in which the
predetermined pattern is generated by the steps of: selecting a
metal mask having at least one slit therein; and positioning the
selected mask over the .[.cornea.]. .Iadd.eye .Iaddend.surface for
scanning the ablation laser thereover for controlling the ablation
slit pattern on the sclera tissue outside the limbus.
12. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by
ablating the sclera in accordance with claim 1 in which said
predetermined pattern includes at least 3 radial lines around the
area of the cornea outside the limbus.
13. A laser beam ophthalmological surgery method for treating
.[.presbyopic.]. .Iadd.presbyopia .Iaddend.in a patient's eye by
ablating the sclera in accordance with claim 1 in which said
predetermined pattern includes a ring pattern around the area of
the cornea outside the limbus.
.Iadd.14. A method of improving accommodation and/or treating
presbyopia, comprising: cutting at least three spaced apart,
substantially radial lines in the scleral tissue of a patient's eye
outside the limbus to a depth of 80-90% of the thickness of the
scleral tissue..Iaddend.
.Iadd.15. A method as in claim 14 wherein the lines are
non-intersecting..Iaddend.
.Iadd.16. A method as in claim 14 wherein the step of cutting is
performed using a pulsed laser..Iaddend.
.Iadd.17. A method as in claim 16 wherein the laser has a spot size
of 0.1 mm to 0.8 mm..Iaddend.
.Iadd.18. A method as in claim 14 wherein the step of cutting is
performed using a laser having a wavelength of approximately
2.6-3.2 microns..Iaddend.
.Iadd.19. A method as in claim 14 wherein the step of cutting is
performed using a laser having a wavelength of about 308
nanometers..Iaddend.
.Iadd.20. A method as in claim 14 wherein the step of cutting is
performed using a laser having a wavelength of about 193
nanometers..Iaddend.
.Iadd.21. A method as in claim 14 wherein the step of cutting is
performed using a laser having an average power of about 30 mW to 3
W..Iaddend.
.Iadd.22. A method as in claim 14 wherein the step of cutting
includes cutting 8 lines in the sclera..Iaddend.
.Iadd.23. A method as in claim 14 wherein the step of cutting
includes using an optical fiber tip to deliver the laser beam to
the sclera..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods and apparatus for the
treatment of presbyopia and the treatment and prevention of
glaucoma using dual-beam scanning lasers.
2. Prior Art
Corneal reshaping, including a procedure called photorefractive
keratectomy (PRK) and a new procedure called laser assisted in situ
keratomileusis, or laser intrastroma keratomileusis (LASIK), has
been performed by lasers in the ultraviolet (UV) wavelength of
193-213 nm. Commercial UV refractive lasers include ArF excimer
lasers at 193 nm and other non-excimer, solid-state lasers, such as
the one patented by the present inventor in 1992 (U.S. Pat. No.
5,144,630). Precise, stable corneal reshaping requires lasers with
strong tissue absorption (or minimum penetration depth) such that
the thermal damage zone is at a minimum (less than few microns).
Furthermore, accuracy of the procedure of vision correction depends
on the amount of tissue removed in each laser pulse, in the order
of about 0.2 microns. Therefore, lasers at UV wavelengths between
193 and 213 nm and at the mid-infrared wavelengths between 2.8 and
3.2 microns are two attractive wavelength ranges which match the
absorption peak of protein and water, respectively.
The above-described prior arts are however limited to the use of
reshaping the corneal surface curvature for the correction of
myopia and hyperopia. A variation of farsightedness that the
existing laser surgery procedures will not treat is presbyopia, and
the gradual age related condition of suddenly fuzzy print and the
necessity of reading glasses. When a person reaches a certain age
(around 40), the eyes start to lose their capability to focus
sharply for near vision. Presbyopia is not due to the cornea but
comes about as the lens loses its ability to accommodate or focus
sharply for near vision as a result of loss of elasticity that is
inevitable as people age.
Thermal lasers such as Ho:YAG have been proposed for the correction
of hyperopia by laser-induced coagulation of the corneal. The
present inventor has also proposed the use of a laser-generated
bifocal for the treatment of presbyopic patients but fundamental
issues caused by age of presbyopic patients still remains unsolved
in those prior approaches.
To treat presbyopic patients, or the reversal of presbyopia, using
the concept of expanding the sclera by mechanical devices has been
proposed by Schaker in U.S. Pat. Nos. 5,529,076, 5,722,952,
5,465,737 and 5,354,331. These mechanical approaches have the
drawbacks of complexity and are time consuming, costly and have
potential side effects. To treat presbyopia, the Schaker U.S. Pat.
Nos. 5,529,076 and 5,722,952 propose the use of heat or radiation
on the corneal epithelium to arrest the growth of the crystalline
lens and also propose the use of lasers to ablate portions of the
thickness of the sclera. However, these prior arts do not present
any details or practical methods or laser parameters for the
presbyopic corrections. No clinical studies have been practiced to
show the effectiveness of the proposed concepts. The concepts
proposed in the Schaker patents regarding lasers suitable for
expanding the sclera tissues were incorrect in that the proposed
lasers did not identify those which are "cold lasers" and can only
conduct the tissue ablation rather than thermal burning of the
cornea. Furthermore, the clinical issues, such as accuracy of the
sclera tissue removal and potential tissue bleeding during the
procedures, were not indicated in these prior patents. In addition,
it is essential to use a scanning laser to achieve the desired
ablation pattern and to control the ablation depth on the sclera
tissue.
One objective of the present invention is to provide an apparatus
and method to obviate these drawbacks in the above Schaker
patents.
It is yet another objective of the present invention to provide an
apparatus and method which provide the well-defined laser
parameters for efficient and accurate sclera expansion for
presbyopia reversal and the treatment and preventing of open angle
glaucoma.
It is yet another objective of the present invention to use a
scanning device such that the degree of ciliary muscle
accommodation can be controlled by the location, size and shapes of
the removed sclera tissue.
It is yet another objective of the present invention to define the
non-thermal lasers for efficient tissue ablation and thermal lasers
for tissue coagulation. This system is able to perform both in an
ablation mode and in a coagulation mode for optimum clinical
outcomes. It is yet another objective of the present invention to
provide an integrated system in which dual-beam lasers can be
scanned over the corneal surface for accurate ablation of the
sclera tissue without bleeding, with ablation and coagulation laser
beams simultaneously applied on the cornea.
It is yet another objective of the present invention to define the
optimal laser parameters and the ablation patterns for best
clinical outcome for presbyopia patients, where sclera expansion
will increase the accommodation of the ciliary muscle.
It is yet another objective of the present invention to provide the
appropriate scanning patterns which will cause effective sclera
expansion.
SUMMARY OF THE INVENTION
The preferred embodiments of the present surgical laser consists of
a combination of an ablative-type laser and a coagulative-type
laser. The ablative-type laser has a wavelength range of from 0.15
to 0.35 microns and from 2.6 to 3.2 microns and is operated in a
Q-switch mode such that the thermal damage of the corneal tissue is
minimized. The coagulative-type lasers includes a thermal laser
having a wavelength of between 0.45 and 0.9 microns and between 1.5
and 3.2 microns, and between 9 and 12 microns operated at a
long-pulse or continuous-wave mode.
It is yet another preferred embodiment of the present invention to
provide a scanning mechanism to effectively ablate the sclera
tissue at a controlled depth by beam overlapping.
It is yet another preferred embodiments of the present invention to
provide an apparatus and method such that both the ablative and the
coagulative lasers can have applied to their beams the corneal
surface to thereby prevent bleeding during the procedure.
It is yet another embodiment of the present invention to provide an
integration system in which a coagulative laser may have the beam
delivered by a scan or by a fiber-coupled device which can be
manually scanned over the cornea. It is yet another embodiment of
the present invention to focus the laser beams in a small circular
spot or a line pattern.
It is yet another embodiment of the present invention to provide a
coagulative laser to prevent the sclera tissue bleeding when a
diamond knife is used for the incision of the sclera.
It is yet another embodiment of the present invention to use a
metal mask on the corneal surface to generate a small slit when the
laser is scanning over the mask. In this embodiment, the exact
laser spot size and its propagating stability are not critical.
It is yet another embodiment of the present invention to provide an
integration system in which the sclera expansion leads to the
increase of the accommodation of the ciliary muscle for the
treatment of presbyopia and the prevention of open angle
glaucoma.
Further preferred embodiments of the present invention will become
apparent from the description of the invention which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of an integrated laser system consisting
of two lasers of different wavelengths coupled to the cornea by
mirrors and a scanning device;
FIG. 2 is a block diagram of a laser system where the coagulative
laser is fiber-coupled and manually delivered to the cornea;
FIG. 3 is the schematic drawing of the anteroposterior section
through the anterior portion of a human eye, where the sclera and
ciliary muscle are shown; and
FIGS. 4A-4D are diagrams of the possible ablation patterns which
will achieve a presbyopia-reversal.
DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED
EMBODIMENTS
FIG. 1 of the drawings is a schematic of a laser system having an
ablative laser 1 producing a laser beam 2 of a predetermined
wavelength and focused by a lens 3 onto a reflecting mirror 4 which
is coupled to another reflecting mirror 5. The system also consists
of a coagulation laser 6 having a laser beam 7 of a predetermined
wavelength focused by a lens 3A through a mirror 5. The ablation
laser 1 beam 2 and the coagulation laser 6 beam 7 are directed onto
a scanner 8. The beams 2 and 7 are then reflected by a mirror 9
onto the cornea 10 of a patient's eye. The scanner 8 consists of a
pair of motorized coated mirrors with a 45 degree highly reflecting
both the ablative laser beam 2 and the coagulative laser beam 7.
The mirror 4 and mirror 9 are highly reflective to the wavelength
of the beams 2 and 7. Mirror 5 is coated such that it is highly
reflective of laser beam 2 but highly transparent to laser beam 7.
The focusing lens 3 has a focal length of about 10-100 cm such that
the spot size of the ablative laser beam 2 is about 0.1-0.8 mm on
the corneal surface. The focusing lens 3A also has a focal length
about 10-100 cm such that the spot size of the coagulative laser
beam 7 is about 0.2-2.0 mm on the corneal surface. In FIG. 1, both
the ablative and the coagulative lasers beams 2 and 7 are scanned
by the scanner 8 over the corneal sclera area of the eye 10 to
generate predetermined patterns, as shown in FIG. 4. In FIG. 1, the
said coagulative laser 6 is used to prevent the potential bleeding
during the ablation process of the sclera tissue. Typically, the
coagulative laser 6 beam 7 has a spot size larger then the ablative
laser 1 beam 2 and has an average power in the range of 20-3000 mW,
depending upon the size of the focused beam. To achieve an
effective coagulation, the temperature increase of the sclera
tissue produced by the coagulative laser beam 7 should be in the
range of 40-70 degree Centigrade. The preferred embodiment of the
laser 1 and 6 includes a pulsed ablative laser with a pulse width
less than 200 nanoseconds such as a Er:YAG laser; Er:YSGG laser; an
optical parametric oscillation (OPO) at 2.6-3.2 microns; a gas
laser with a wavelength of 2.6-3.2 microns; an excimer laser of ArF
at 193 nm; a XeCl laser at 308 nm; a frequency-shifted solid state
laser at 0.15-3.2 microns; a CO laser at about 6.0 microns and a
carbon dioxide laser at 10.6 microns. The long pulse coagulative
lasers have a pulse longer than 200 nanoseconds of a green laser;
or an argon laser; or a Ho:YAG at 2.1 microns; or a Er:glass at
1.54 microns; or an Er:YAG; or an Er:YSGG; or a diode laser at
0.8-2.1 microns, or any other gas lasers at 0.8-10.6 microns. To
achieve the ablation of the sclera tissue at the preferred laser
spot size of 0.1-0.8 mm requires an ablative laser energy per pulse
of about 0.1-5.0 mJ depending on the pulse duration. On the other
hand, the coagulative laser should have an, average power of about
30 mW for a small spot and about to 3 W for a larger spot.
Referring to FIG. 2, an alternative schematic for the coagulative
laser 6 is coupled to a fiber 11 for delivery of the beam to the
cornea, where a line pattern may be performed by manually scanning
the beam over the cornea. Alternatively, a fiber-coupled
coagulation laser 6 may be focused by a cylinder lens to form a
line spot on the cornea where a typical spot size of 0.2-2.0
mm.times.3.0-5.0 mm is preferred. In FIG. 2, the ablative laser 1
has the same schematic as that of FIG. 1 where the laser beam 2 is
coupled to the scanner 8 and reflected by the mirror 9 onto the
cornea. An alternative embodiment of the present invention is to
use a cylinder lens to focus the ablative laser 1 to a line spot
with a size of 0.1-0.8 mm.times.3.0-5.0 mm on the corneal surface
to eliminate the scanner 8. Another embodiment may use an optical
fiber or an articulate arm to deliver both the coagulative and
ablative laser beams such that the presbyopia treatment may be
conducted manually without the need of a scanner or reflecting
mirrors.
FIG. 3 shows the lens of a human eye 12 connected to the sclera 13
and ciliary body 14 by zonule fibers 15. Expansion of the sclera 13
will cause the ciliary muscle to contract and the lens becomes more
spherical in topography with a shorter radii of curvature for near
objects. The reversed process of ciliary muscle relaxation will
cause a longer radii of curvature for distant objects. Therefore,
laser ablation of the sclera tissue will increase the accommodation
of the ciliary body for the presbyopic patient to see both near and
distance. For efficient sclera expansion, the depth of the laser
ablation needs to be approximately 80%-90% of the sclera thickness
which is about 500-700 microns. For safety reasons, the ablation
depth should not cut through the choroid. It is therefore
clinically important that the patient's sclera thickness be
measured pre-operatively and the laser ablation depth controlled. A
scanning laser is used to control this depth by the number of
scanning lines or slots over the selected area at a given set of
laser parameters. Pre-operatively, PMMA is used to calibrate the
depth of tissue ablation. Alternatively, the surgeon may observe
the color change of the ablated sclera tissue to determine when the
ablation depth reaches the interface of the sclera and the
ciliary.
FIG. 4 shows examples of ablation patterns which will cause sclera
expansion and increase the accommodation of the presbyopic patient.
As shown in FIG. 4A, line patterns are conducted between circles 16
and 17 which have diameters of about 8-11 mm and 12-15 mm,
respectively. The width of the ablated lines are about 0.1-0.5 mm
with a depth of 80%-90% of the sclera. Eight (8) lines are shown in
FIG. 4A as an example but it can be more or less without departing
from the spirit and scope of the invention. Enhancement may be
performed by adding more ablation lines. FIG. 4B shows a ring
pattern with a diameter 18 of about 12-14 mm. A two-ring pattern 19
is shown in FIG. 4C where two circles have diameters of about 10 mm
and 12 mm, respectively. Another example of an ablation pattern is
shown in FIG. 4D where the ablation laser is focused to a round
spot 20 of about 0.1-0.5 mm in diameter and scanned over the sclera
area to form an eight spot symmetric ring which has a diameter of
about 12-14 mm. In all the above described ablative patterns, the
coagulative laser described in FIGS. 1 and 2 simultaneously deliver
these patterns such that the sclera tissue may be coagulated as the
tissue is being ablated. The preferred spot sizes of the
coagulative lasers are larger than that of the ablative laser so
that the alignment of the coagulative laser is not critical.
Another embodiment of controlling the ablation area of the sclera
area is to use a metal mask which has a plurality of slits each
having an approximate dimension of 0.1-0.3 mm.times.3.0-5.0 mm.
Both of the ablative and coagulative lasers will scan over the mask
which is placed on the corneal surface to generate the desired slit
pattern on the sclera. In this embodiment using a mask, the small
laser spot sizes of 0.1 mm, which may be difficult to achieve, are
not needed in order to generate the slit size on the cornea. Laser
spot sizes of 0.2-1.0 mm will generate the desired ablation
dimension on the sclera after scanning over the mask. Furthermore,
the embodiment of using a mask will not require a precise stability
of the laser beam path onto the corneal surface. Without using a
mask, both the exact laser beam spot size and its stability in
propagating would be essential.
Another embodiment of sclera expansion of the present invention is
to use diamond knife for the incision of the sclera tissue in the
patterns described in FIGS. 4A, 4B and 4C where the coagulation
laser is simultaneously applied onto the cut tissue to prevent
bleeding. The incision depth should be about 80% to 90% of the
sclera thickness in order to achieve the effects of sclera
expansion. Accordingly, the pre-operative measurement of the sclera
thickness is essential for the knife incision procedure and
surgeon's skill is more important than that of using an ablative
laser, in which the ablation depth of the sclera tissue is well
controlled by the numbers of scanning lines in a given pattern. We
are able to calibrate the ablation rate of various lasers on the
sclera tissue by comparing the clinical data and that of the
selected materials including a PMMA plastic sheet.
The invention having now been fully described, it should be
understood that it may be embodied in other specific forms or
variations without departing from the spirit or essential
characteristics of the present invention. Accordingly, the
embodiments described herein are to be considered to be
illustrative and not restrictive.
* * * * *