U.S. patent application number 14/307639 was filed with the patent office on 2017-05-25 for design of myopia control ophthalmic lenses.
This patent application is currently assigned to Johnson & Johnson Vision Care, Inc.. The applicant listed for this patent is Johnson & Johnson Vision Care, Inc.. Invention is credited to Khaled A. Chehab, Xu Cheng, Michael J. Collins, Brett A. Davis, Daoud Robert Iskander.
Application Number | 20170146821 14/307639 |
Document ID | / |
Family ID | 42357257 |
Filed Date | 2017-05-25 |
United States Patent
Application |
20170146821 |
Kind Code |
A9 |
Collins; Michael J. ; et
al. |
May 25, 2017 |
DESIGN OF MYOPIA CONTROL OPHTHALMIC LENSES
Abstract
Lenses are designed using the corneal topography or wavefront
measurements of the eye derived by subtracting the optical power of
the eye after orthokeratology treatment from the optical power
before orthokeratology treatment.
Inventors: |
Collins; Michael J.;
(Queensland, AU) ; Davis; Brett A.; (Queensland,
AU) ; Chehab; Khaled A.; (Jacksonville, FL) ;
Cheng; Xu; (St. Johns, FL) ; Iskander; Daoud
Robert; (Wroclaw, PL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Johnson & Johnson Vision Care, Inc. |
Jacksonville |
FL |
US |
|
|
Assignee: |
Johnson & Johnson Vision Care,
Inc.
Jacksonville
FL
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20140320800 A1 |
October 30, 2014 |
|
|
Family ID: |
42357257 |
Appl. No.: |
14/307639 |
Filed: |
June 18, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12821927 |
Jun 23, 2010 |
8789947 |
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14307639 |
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61220487 |
Jun 25, 2009 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02C 7/04 20130101; G02C
7/024 20130101; G02C 7/047 20130101; G02C 2202/24 20130101; G02C
7/028 20130101; G02C 7/027 20130101 |
International
Class: |
G02C 7/04 20060101
G02C007/04; G02C 7/02 20060101 G02C007/02 |
Claims
1) An ophthalmic lens comprising a design that corrects myopia or
myopic astigmatism and includes correction factors based on corneal
topography or wavefront data acquired before and after
orthokeratology treatment wherein the use of the lens slows or
stops the progression of myopia.
2) The lens of claim 1 comprising: A convex surface with a central
optic zone surrounded by a peripheral zone further surrounded by an
edge zone, and a concave surface which rests on the wearer's eye;
wherein the lens power at any location in the optical zone is
derived by subtracting the optical power of the eye after
orthokeratology treatment from the optical power before
orthokeratology treatment, to derive the optical power at each
location (x), the optical lens power being useful in controlling or
slowing the progression of myopia.
3) The method of claim 2 wherein the total population data is
acquired.
4) The method of claim 2 wherein sub-population data is
acquired.
5) The method of claim 2 wherein data for an individual is
acquired.
6) The method of claim 2 wherein the data is an average of multiple
corneal topography files.
7) The method of claim 2 wherein the data is an average of multiple
wavefront files.
8) The method of claim 2 wherein the lens design power profile is
calculated by averaging all meridians to a rotationally symmetric
form.
9) The method of claim 2 wherein the lens design power profile is
calculated by averaging individual meridians to a non-rotationally
symmetric form.
10) (canceled)
11) (canceled)
12) An article comprising computer-usable medium having computer
readable instructions stored thereon for execution by a processor
to perform a method comprising: generating a lens design by
converting corneal topography data characterizing an eye to a
radial power map and generating a lens power profile that includes
correction factors based on corneal topography.
13) The article of claim 12 that produces a lens design for a lens
with a convex surface with a central optic zone surrounded by a
peripheral zone which is further surrounded by an edge zone, and a
concave surface which rests on the wearer's eye.
14) The article of claim 12 wherein the lens power at any location
in the optical zone is described by converting corneal topography
data before and after orthokeratology treatment to radial power
maps and subtracting the pre treatment map from the post treatment
map to generate a corneal topography derived power at each location
(x).
15) The article of claim 12 wherein the lens power at any location
in the optical zone is described by converting ocular wavefront
data before and after orthokeratology treatment to radial power
maps and subtracting the pre treatment map from the post treatment
map to generate a corneal topography derived power at each location
(x).
16) An ophthalmic lens for the slowing of myopia progression
comprising: a) a convex surface with a central optic zone
surrounded by a peripheral zone which is further surrounded by an
edge zone, and a concave surface which rests on the wearer's eye;
b) the central optic zone containing an inner disc, and a plurality
of annuli; and a lens power at any location in the optical zone is
described by subtracting the optical power of the eye after
orthokeratology treatment from the optical power before
orthokeratology treatment; the lenses made using these designs are
useful in controlling or slowing the progression of myopia.
17) The lens of claim 16 wherein the inner disc has a diameter less
than 2 mm.
18) The lens of claim 16 wherein the optical power of the inner
disc is substantially constant.
19) The lens of claim 16 wherein the first annulus has an outer
diameter between 6.0 to 7.0 mm.
20) The lens of claim 16 wherein the optical power of the first
annulus at a diameter of 4 mm is between +0.5 and +1.5 D.
21) The lens of claim 16 wherein the optical power of the first
annulus at a diameter of 6.5 mm is between +1.5 and +5.5 D.
22) The lens of claim 16, wherein the second annulus surrounding
the first annulus has an outer diameter between 7.25 and 7.75
mm.
23) The lens of claim 16 wherein the optical power of the second
annulus decreases smoothly from the power found at the edge of the
first annulus smoothly to between +1.5 and +4.5 D.
24) The lens of claim 16, wherein the third annulus surrounding the
second annulus has an outer diameter between 7.5 and 8.5 mm.
25) The lens of claim 16, wherein the optical power of the fourth
annulus is substantially constant with the power found at the edge
of the second annulus.
26) An ophthalmic lens for the slowing of myopia progression
comprising: a) a convex surface with a central optic zone
surrounded by a peripheral zone which is further surrounded by an
edge zone, and a concave surface which rests on the wearer's eye;
b) the central optic zone containing an inner disc, and a plurality
of annuli; and a lens power at any location in the optical zone is
described by subtracting the optical power of the eye after
orthokeratology treatment from the optical power before
orthokeratology treatment; the lenses made using these designs are
useful in controlling or slowing the progression of myopia.
27) The lens of claim 26 wherein the inner disc has a diameter less
than 2 mm.
28) The lens of claim 26 wherein the optical power of the inner
disc is substantially constant.
29) The lens of claim 26 wherein the first annulus has an outer
diameter between 6.0 to 7.0 mm.
30) The lens of claim 26 wherein the optical power of the first
annulus is described by the equation:
Power=0.486x.sup.6-5.8447x.sup.5+27.568x.sup.4-65.028x.sup.3+81.52x.sup.2-
-51.447x+12.773 where x is the radial distance from the center of
the lens.
31) The lens of claim 26, wherein the second annulus surrounding
the first annulus has an outer diameter between 7.25 and 7.75
mm.
32) The lens of claim 26 wherein the optical power of the second
annulus decreases smoothly from the power found at the edge of the
first annulus smoothly to between +2.00 and +3.25 D.
33) The lens of claim 26, wherein the third annulus surrounding the
second annulus has an outer diameter between 7.5 and 8.5 mm.
34) The lens of claim 26, wherein the optical power of the fourth
annulus is substantially constant with the power found at the edge
of the second annulus.
35) An ophthalmic lens for the slowing of myopia progression
wherein at least a portion of the optical zone is described by the
equation:
Power=0.486x.sup.6-5.8447x.sup.5+27.568x.sup.4-65.028x.sup.3+81.52x.sup.2-
-51.447x+12.773 where x is the radial distance from the center of
the lens.
36) An ophthalmic lens for the slowing of myopia progression
comprising: a) a convex surface with a central optic zone
surrounded by a peripheral zone which is further surrounded by an
edge zone, and a concave surface which rests on the wearer's eye;
b) the central optic zone containing an inner disc, and a plurality
of annuli; and a lens power at any location in the optical zone is
a myopia controlling or slowing amount of power.
37) The lens of claim 36 wherein the inner disc has a diameter less
than 2 mm.
38) The lens of claim 36 wherein the optical power of the inner
disc is substantially constant.
39) The lens of claim 36 wherein the first annulus has an outer
diameter between 6.0 to 7.0 mm.
40) The lens of claim 36 wherein the optical power of the first
annulus is described by the equation:
Power=0.486x.sup.6-5.8447x.sup.5+27.568x.sup.4-65.028x.sup.3+81.52x.sup.2-
-51.447x+12.773 where x is the radial distance from the center of
the lens.
41) The lens of claim 36, wherein the second annulus surrounding
the first annulus has an outer diameter between 7.25 and 7.75
mm.
42) The lens of claim 36 wherein the optical power of the second
annulus decreases smoothly from the power found at the edge of the
first annulus smoothly to between +2.00 and +3.25 D.
43) The lens of claim 36, wherein the third annulus surrounding the
second annulus has an outer diameter between 7.5 and 8.5 mm.
44) The lens of claim 36, wherein the optical power of the fourth
annulus is substantially constant with the power found at the edge
of the second annulus.
45) An ophthalmic lens for the slowing of myopia progression
wherein at least a portion of the optical zone is described by the
equation:
Power=0.486x.sup.6-5.8447x.sup.5+27.568x.sup.4-65.028x.sup.3+81.52x.sup.2-
-51.447x+12.773 where x is the radial distance from the center of
the lens.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to designs and methods for
preventing, stopping or slowing myopia progression.
[0002] Myopia, also known as short-sightedness, is a refractive
condition wherein the overall power of the eye is too high, or too
strong, causing light from distant objects to focus in front of the
retina. This is perceived by the viewer as blurring of distant
objects, with the amount of blurring being related to the severity
of the myopia. This condition is often first seen in childhood, and
usually noticed at school age. A progression, or increase, in the
severity of myopia, is usually seen in myopic cases until young
adulthood.
[0003] U.S. Pat. No. 6,045,578 proposes methods of using on-axis
longitudinal spherical aberration (LSA) in contact lens designs to
attempt to halt myopia progression. The design approach suggested
does not appear to address specific wavefront/refractive power
characteristics of the individual eye/or group average data or
changes in pupil size associated with close work.
[0004] U.S. Pat. No. 7,025,460 proposes methods of altering field
curvature (off-axis focal point variation) to try to halt myopia
progression. The mathematics behind this approach uses "extended
conics" where the simple conic equations have even ordered
polynomial terms added to them. These conic and polynomial terms
are processed so that the contact lens surface shape of the
proposed design produces the required amount of field
curvature.
[0005] US 2003/0058404 and US 2008/0309882 proposes a method of
measuring the wavefront of the eye and correcting the wavefront of
the eye with a customized correction to slow myopia progression.
Pupil size changes associated with near tasks were not an aspect of
the design process.
[0006] EP 1853961 proposes the measurement of the wavefront before
and after near work. The changes in wavefront aberrations are then
corrected with a custom contact lens. Group or population data to
create a design to control eye growth are not included.
[0007] "Orthokeratology Alters Aberrations of The Eye", Optometry
and Vision Science, May 2009. The article discusses higher order
aberrations of the eye associated with orthokeratology.
[0008] A more complete approach to slowing or stopping myopia
progression is still desired. This is addressed in this
specification.
SUMMARY OF THE INVENTION
[0009] In one aspect of the invention a method and resulting design
to be used in the fabrication of ophthalmic lenses useful in
controlling and slowing the progression of myopia incorporates the
use of corneal topographic data from the eye. Ophthalmic lenses
include, for example, contact lenses, intraocular lenses, corneal
inlays, and corneal onlays.
[0010] In another aspect of the invention the method and resulting
designs to be used in the fabrication of ophthalmic lenses useful
in controlling and slowing the progression of myopia incorporates
the use of wavefront data from the eye.
[0011] In yet another aspect of the invention, a design for an
ophthalmic lens produced according to the methods of the invention
includes a convex surface with a central optic zone surrounded by a
peripheral zone which is further surrounded by an edge zone, and a
concave surface which rests on the wearer's eye; the central optic
zone containing an inner disc, and a plurality of annuli; and a
lens power at any location in the optical zone is described by
subtracting the optical power of the eye after orthokeratology
treatment from the optical power before orthokeratology treatment;
the lenses made using these designs are useful in controlling or
slowing the progression of myopia.
[0012] In another aspect of the invention, a method to generate an
ophthalmic lens design includes the steps of acquiring corneal
topographic data before and after orthokeratology treatment,
converting the corneal topographic data to radial power maps,
subtracting the post from the pre treatment map and generating a
lens power profile.
[0013] In another aspect of the invention, a method to generate an
ophthalmic lens design includes the steps of acquiring wavefront
data before and after orthokeratology treatment, converting the
wavefront data to refractive power maps, subtracting the post from
the pre treatment map and generating a lens power profile.
[0014] In yet another aspect of the invention, data for the total
population is considered.
[0015] In yet another aspect of the invention, data for a
sub-population is considered.
[0016] In yet another aspect of the invention, data for an
individual subject is considered.
[0017] In yet another aspect of the invention, data is an averaged
over multiple files.
[0018] In yet another aspect of the invention, the lens design
power profile is calculated by averaging all meridians to a
rotationally symmetric form.
[0019] In yet another aspect of the invention, the lens design
power profile is calculated by averaging individual meridians to a
non-rotationally symmetric form.
[0020] In yet another aspect of the invention, methods of designing
lenses for slowing myopia progression are encoded into instructions
such as machine instructions and are programmed into a
computer.
[0021] In yet another aspect of the invention, articles include
executable instructions for designing lenses for slowing myopia
progression; the method includes converting corneal topographic
data characterizing an eye to a radial power map, generating a lens
power profile and using the power profile to produce a lens design
for a lens with a convex surface with a central optic zone
surrounded by a peripheral zone which is further surrounded by an
edge zone, and a concave surface which rests on the wearer's eye;
the central optic zone containing an inner disc, and a plurality of
annuli; the lens power at any location in the optical zone is
described by subtracting the optical power of the eye after
orthokeratology treatment from the optical power before
orthokeratology treatment.
[0022] In yet another aspect of the invention, articles include
executable instructions for designing lenses for slowing myopia
progression; the method includes converting wavefront data
characterizing an eye to a refractive power map, generating a lens
power profile and using the power profile to produce a lens design
for a lens with a convex surface with a central optic zone
surrounded by a peripheral zone which is further surrounded by an
edge zone, and a concave surface which rests on the wearer's eye;
the central optic zone containing an inner disc, and a plurality of
annuli; the lens power at any location in the optical zone is
described by subtracting the optical power of the eye after
orthokeratology treatment from the optical power before
orthokeratology treatment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 shows the averaged pre treatment corneal topography
maps of a group of 26 subjects prior to orthokeratology.
[0024] FIG. 2 shows the averaged post treatment corneal topography
maps of a group of 26 subjects subsequent to orthokeratology.
[0025] FIG. 3 shows the difference between the averaged post and
pre treatment corneal topography maps of a group of 26 subjects
having undergone orthokeratology treatment.
[0026] FIG. 4 shows the difference between the averaged post and
pre treatment corneal topography maps of a group of 26 subjects
having undergone orthokeratology treatment, truncated to a diameter
of 6 mm.
[0027] FIG. 5 shows the power profile of a lens design, according
to the invention.
[0028] FIG. 6 shows the envelope of design profiles based upon
scaling of the averages all of the meridians in the example above,
according to the invention.
DETAILED DESCRIPTION
[0029] Orthokeratology (sometimes called corneal refractive
therapy) is the practice of fitting rigid contact lenses to
deliberately alter the shape of the central cornea. By making the
central cornea flatter in curvature, the optical power of the
cornea (and therefore total eye) decreases. This has the effect of
reducing the degree of myopia of the eye. Specially designed rigid
contact lenses are typically worn overnight (during sleep) and
removed in the morning. The pressure exerted by the rigid lens on
the cornea during sleep, temporarily flattens the central cornea.
This flattening leads to a reduction of myopia which gradually
regresses (i.e. the cornea returns to its normal shape) over the
next 1 to 3 days. The orthokeratology patient wears the rigid lens
during sleep every 1 to 3 nights, depending upon the rate of
regression and thereby maintains a reduced level of myopia during
the waking hours (without the need to wear any form of contact
lenses or spectacles).
[0030] An unintended consequence of orthokeratology has been the
reduction of the rate of myopia progression in patients using this
form of myopia correction. Studies by Cho et al (LORIC study) and
Walline et al (CRAYON study) have both shown that patients wearing
orthokeratology lenses not only have a reduction in myopia, but a
reduction in the rate of myopia progression (i.e. eye growth). A
likely explanation for this reduction in the rate of myopia
progression is the optical changes induced in the cornea by
orthokeratology. In effect, orthokeratology changes the corneal
optics so that the central refractive power is more minus (less
positive), while the peripheral corneal power is more positive
(less minus).
[0031] In a preferred embodiment, the methods of the invention
involve using corneal topography data to design and produce contact
lenses useful for treating, slowing, and sometimes stopping the
progression of myopia. Corneal topography data is collected from a
patient using a videokeratoscope such as a Keratron or Keratron
Scout (Optikon 2000; Rome, Italy). This topographic data is
available in several formats. The preferred format in the present
invention is to depict the cornea as a refractive power data.
[0032] FIG. 1 shows the average corneal refractive power of 26 eyes
prior to orthokeratology as measured by a videokeratoscope, and
FIG. 2 shows a videokeratoscope image of the same 26 eyes after
treatment by orthokeratology. The change in corneal power is
derived by subtracting the refractive power of the cornea before
and after orthokeratology. This map of refractive power change
shows the central shift of power in the minus direction (i.e. blue
colors) and the peripheral shift in powers in the positive
direction (i.e. red colors), and is shown in FIG. 3. The difference
map is the basis for the design power profile reported herein, and
will control the rate of myopia progression.
[0033] In one embodiment, these maps are centered around the
videokeratoscope axis (the axis at which the videokeratoscope
measures the corneal shape), however in a preferred embodiment they
could also be resampled and centered around the pupil of the eye
(i.e. the entrance pupil of the eye at the corneal plane). The
pupil center and videokeratoscope axis rarely coincide. In terms of
optical design, it is preferable to center the optical design along
the axis of the entrance pupil center.
[0034] The next step in the process of deriving the soft lens
optical design is to reduce the two-dimensional refractive power
difference map into an average power change of all of the meridians
averaged together, resulting in a symmetric average power map. FIG.
4 illustrates this process for a two dimensional refractive power
difference map, limited to a diameter of 6 mm.
[0035] In an alternate embodiment, the power difference map is
reduced to a two-dimensional refractive power difference map by
averaging the power change of each of the meridians, the individual
meridians being averaged separately, resulting in a
non-rotationally symmetric average power map.
[0036] In a preferred embodiment, it is desirable to extend the
design power profile beyond the 6 mm limitation out to 8 mm, and to
create a power profile which provides for a better clinical outcome
and helps to prevent providing excessive amounts of plus optical
power to the wearer. In a preferred embodiment, the plus optical
power is first decreased and then leveled off
[0037] In a preferred embodiment, a design for an ophthalmic lens
produced according to the methods of the invention includes a
convex surface with a central optic zone surrounded by a peripheral
zone which is further surrounded by an edge zone, and a concave
surface which rests on the wearer's eye; the central optic zone
containing an inner disc, and a plurality of annuli; and a lens
power at any location in the optical zone is described by
subtracting the optical power of the eye after orthokeratology
treatment from the optical power before orthokeratology treatment;
the lenses made using these designs are useful in controlling or
slowing the progression of myopia.
[0038] FIG. 5 shows the power profile of a preferred embodiment. In
this preferred embodiment, the central optic zone contains an inner
disc, with the range of usable diameter between 0 and 2 mm, the
preferred diameter about 1.5 mm; a first annulus with an outer
diameter between 6.0 to 7.0 mm, the preferred diameter about 6.5
mm; a second annulus surrounding the first annulus with an outer
diameter between 7.25 and 7.75 mm, the preferred diameter about 7.5
mm; and a third annulus surrounding the second annulus, with a
diameter between 7.5 and 8.5 mm, the preferred diameter being 8
mm.
[0039] The optical power shown in FIG. 5 is based upon the
reduction of data for a population mean. The powers shown would be
added to the initial distance prescription of the wearer. The
optical power in the central disc of the optic zone is
substantially constant; the optical power in the first annulus, at
a diameter of 4 mm increases in plus power to a range of +0.5 to
+1.5 diopters, with a preferred value of about +1.0 diopter, at a
diameter of 6.5 mm has increased in plus value to a range of +1.5
to +5.5 D, with a preferred value of about +3.4 D; the optical
power in the second annulus decreasing smoothly from the power
found at the edge of the first annulus to a power between about
+1.5 and +4.5 D, with a preferred value of about +3.0 D; the
optical power of the third annulus being substantially constant at
about the power found at the edge of the second annulus.
[0040] Distance refractive prescription powers that are
substantially different than -3.00 D may require scaling of the
power profile. FIG. 6 shows a preferred embodiment of a scaled
envelope of resultant refractive power curves that can be
calculated and applied to a lens design from the averaged data
shown above. It is thus advantageous with this inventive design to
create a family of design power profiles. These are created by
proportionally multiplying a scaling factor for each point in the
aperture; the range of the scaling factor between 0.25 and 4, 0.5
to 1.5 being the preferred range.
[0041] The preferred process steps for generating a lens design
power profile by this method are as follows: [0042] 1) Acquire and
average corneal topography refractive power data maps for eyes pre
orthokeratology treatment, [0043] 2) Acquire and average corneal
refractive power data maps for eyes post orthokeratology treatment,
[0044] 3) Subtract the pre treatment from the post treatment maps,
[0045] 4) Average all of the meridians together to generate a
rotationally symmetric power map. [0046] 5) Alternately average the
individual meridians together to generate a non-rotationally
symmetric power map. [0047] 6) Trim the maps to a convenient
uniform diameter, [0048] 7) Optionally extend the profile out to a
larger diameter by decreasing the plus optical power and then flat
leveling the power. [0049] 8) Optionally generate an envelope of
average resultant power profiles by proportional scaling.
[0050] In an alternate embodiment, the methods of the invention
involve using wavefront data to design and produce contact lenses
useful for treating, slowing, and sometimes stopping the
progression of myopia. Ocular wavefront data is collected from a
patient using a wavefront sensor such as a COAS (wavefront Sciences
Inc, Albuquerque N. Mex.). This wavefront data is generally in the
form of Zernike polynomial coefficients but can also be a set of
wavefront heights at specified Cartesian or polar coordinates. A
preferred system to designate the Zernike coefficients has been
described as the OSA method, in ANSI Z80.28.
[0051] The preferred process steps for generating a lens design
power profile by this method are as follows: [0052] 1) Acquire and
average ocular wavefront data maps for eyes prior to
orthokeratology treatment. Each wavefront is converted to a
refractive power map by calculating the powers based upon the
radial slopes in the direction of the z axis, defined as the front
to back axis, e.g. along the visual axis through the pupil center.
[0053] 2) Acquire and average ocular wavefront data maps for eyes
post orthokeratology treatment. Each wavefront is converted to a
refractive power map by estimating the radial slopes in the
direction of the z axis, defined as the front to back axis, e.g.
along the visual axis through the pupil center. [0054] 3) Subtract
the pre treatment from the post treatment maps. [0055] 4) Average
all of the meridians together to generate a rotationally symmetric
power map. [0056] 5) Alternately average the individual meridians
together to generate a non-rotationally symmetric power map. [0057]
6) Trim the maps to a convenient diameter [0058] 7) Optionally
extend the profile out to a larger diameter by decreasing the
optical power and then flat leveling the power. [0059] 8)
Optionally generate an envelope of average resultant power profiles
by proportional scaling.
[0060] In this method, a refractive power map is calculated from
the set of estimated wavefront Zernike coefficients using the
refractive Zernike power polynomials, .PSI..sub.j(.rho.,.theta.),
as follows (see Iskander et al., 2007, attached)
F ^ ( r , .theta. ) = 10 3 r max j = 3 P - 1 c j .PSI. j ( r / r
max , .theta. ) ( 1 ) ##EQU00001##
where c.sub.j are the wavefront Zernike polynomial coefficients,
r.sub.max corresponds to the pupil radius,
.PSI. j ( .rho. , .theta. ) = { 2 ( n + 1 ) Q n m ( .rho. ) cos ( m
.theta. ) , m > 0 2 ( n + 1 ) Q n m ( .rho. ) sin ( m .theta. )
, m < 0 n + 1 Q n m ( .rho. ) n = 0 ( 2 ) Q n m ( .rho. ) = s =
0 ( n - m ) / 2 - q ( - 1 ) s ( n - s ) ! ( n - 2 s ) s ! ( ( n + m
) / 2 - s ) ! ( ( n - m ) / 2 - s ) ! .rho. n - 2 s - 2 q = { 1 , m
.ltoreq. 1 0 , otherwise . ( 3 ) ##EQU00002##
[0061] Other methods are known by those skilled in the art to
generate or calculate refractive power values from wavefront data.
Ocular pupil sizes are also estimated either directly from the
wavefront measurement or by an independent pupil measurement (e.g.
using a pupillometer). If the pupil is measured independently of
the wavefront, it should be measured under similar lighting
conditions.
[0062] The method can be used to design lenses for individuals on a
custom lens basis or averaged for populations, or sub-populations.
This method can be used to produce a rotationally symmetric design
where all optic zone meridians are the same, or a non-rotationally
symmetric design where each meridian is unique and the result of
the analysis of comparing topography or wavefront before and after
orthokeratology.
[0063] The ophthalmic lens made according to the invention has the
following parts and characteristics: [0064] a) a convex surface
with a central optic zone surrounded by a peripheral zone which is
further surrounded by an edge zone, and a concave surface which
rests on the patient's eye; [0065] b) the lens power at any
location in the optical zone is described by subtracting the
optical power of the eye after orthokeratology treatment from the
optical power before orthokeratology treatment.
[0066] In another preferred embodiment, the ophthalmic lens made
according to the invention has the following parts and
characteristics: [0067] a) A central optic zone, the central optic
zone contains an inner disc, with the range of usable diameter
between 0 and 2 mm, the preferred diameter about 1.5 mm; [0068] b)
a first annulus with an outer diameter between 6.0 to 7.0 mm, the
preferred diameter about 6.5 mm; [0069] c) a second annulus
surrounding the first annulus with an outer diameter between 7.25
and 7.75 mm, the preferred diameter about 7.5 mm; [0070] d) a third
annulus surrounding the second annulus, with a diameter between 7.5
and 8.5 mm, the preferred diameter being about 8.0 mm.
[0071] In another preferred aspect of the present invention, the
ophthalmic lens made according to the invention has the following
parts and characteristics: [0072] a) The optical power in the
central disc of the optic zone is substantially constant; [0073] b)
the optical power in the first annulus at about a diameter of 4 mm
increases in plus power to a range of +0.5 to +1.5 D, with a
preferred value of about +1.0 D, at a diameter of 6.5 mm increases
in plus power to a range +1.5 to +5.5 D, with a preferred value of
about +3.4 D; [0074] c) the optical power in the second annulus
decreasing smoothly from the power found at the edge of the first
annulus to a power between +1.5 and +4.5 D, with a preferred value
of about +3.0 D; [0075] d) the optical power of the third annulus
being substantially constant at about the power found at the edge
of the second annulus.
[0076] In another preferred aspect of the present invention, the
ophthalmic lens made according to the invention has the following
parts and characteristics: [0077] a) The optical power in the
central disc of the optic zone is substantially constant; [0078] b)
the optical power in the first annulus increases in plus power by a
suitable polynomial equation of 4.sup.th order or higher; [0079] in
a preferred aspect, the power change in the first annulus is
governed by the equation:
Power=0.486x.sup.6-5.8447x.sup.5+27.568x.sup.4-65.028x.sup.3+81.52x.sup.2-
-51.447x+12.773 where x is the radial distance from the center of
the lens. [0080] c) the optical power in the second annulus
decreasing from the power found at the edge of the first annulus to
a power between +1.5 and +4.5 D, with a preferred value of about
+3.0 D; [0081] d) the optical power of the third annulus being
substantially constant at about the power found at the edge of the
second annulus.
[0082] It is recognized by those skilled in the art that the power
in the central optical zone of the lens is a result of the powers
of the back surface and front surface working together. The
variations in power described by the method and design of the
present invention may be applied to the front surface, back
surface, or any combination thereof. In a preferred embodiment, the
power variations described by the method and design of the present
invention are applied to the front surface.
[0083] Power Profile Driven Ophthalmic Lens Design Methods:
[0084] Different data sources can be used to derive a contact lens
design for myopia control. Examples include:
[0085] A customized design based on the individual subjects data,
or
[0086] A group design based on a particular sub-population of data
(e.g. young Asian children aged 10-16 years of age), or
[0087] A general population design based on all available data
(e.g. all myopes).
[0088] Additionally, both rotationally symmetric designs or
non-rotationally symmetric designs are obtainable using the method
of the invention. When data is averaged across all considered
semi-meridians or it can be used to create rotationally symmetrical
designs, or if the data is retained in its semi-meridional form it
can be used to create non-rotationally symmetric designs.
Non-rotationally symmetric correction forms include, but are not
limited to toric, sphero-cylindrical, sphero-cylindrical with
higher order aberration correction. Toric includes the correction
of both regular and irregular astigmatism.
[0089] The following is an exemplary design method pursuant to the
present invention, obtained using averaged data from all of the
considered semi-meridians. This approach will result in a
rotationally symmetric design.
[0090] Method 1:
[0091] In the first method, pre and post orthokeratology maps are
used as the starting point for the design. The pre orthokeratology
map is subtracted from the post, and then the meridians are
averaged. This will create the power profile shown in FIG. 5. This
power profile is then applied to the base design of a lens for a
myope requiring a -3.00 DS lens, to retard the advance of myopia.
In method 1, the design power of the first annulus within the
central optical zone was calculated mathematically as follows:
Power=0.486x.sup.6-5.8447x.sup.5+27.568x.sup.4-65.028x.sup.3+81.52x.sup.-
2-51.447x+12.773
where x is the radial distance from the center of the lens.
[0092] The methods of the invention can be embodied as computer
readable code on a computer readable medium. The computer readable
medium is any data storage device that can store data, which
thereafter can be read by a computer system. Examples of computer
readable medium include read-only memory, random-access memory,
CD-ROMs, DVDs, magnetic tape, optical data storage devices. The
computer readable medium can also be distributed over network
coupled computer systems so that the computer readable code is
stored and executed in a distributed fashion.
[0093] The invention may be implemented using computer programming
or engineering techniques including computer software, firmware,
hardware or any combination or subset thereof. Any such resulting
program, having computer-readable code means, may be embodied or
provided within one or more computer-readable media, thereby making
a computer program product, i.e., an article of manufacture,
according to the invention. The computer readable media may be, for
example, a fixed (hard) drive, diskette, optical disk, magnetic
tape, semiconductor memory such as read-only memory (ROM), etc., or
any transmitting/receiving medium such as the Internet or other
communication network or link. The article of manufacture
containing the computer code may be made and/or used by executing
the code directly from one medium, by copying the code from one
medium to another medium, or by transmitting the code over a
network.
[0094] Devices according to the invention may also be one or more
processing systems including, but not limited to, a central
processing unit (CPU), memory, storage devices, communication links
and devices, servers, I/O devices, or any sub-components of one or
more processing systems, including software, firmware, hardware or
any combination or subset thereof, which embody the invention as
set forth in the claims.
[0095] User input may be received from the keyboard, mouse, pen,
voice, touch screen, or any other means by which a human can input
data to a computer, including through other programs such as
application programs.
[0096] One skilled in the art of computer science will readily be
able to combine the software created as described with appropriate
general purpose or special purpose computer hardware to create a
computer system or computer sub-system embodying the method of the
invention.
[0097] The methods embodied in, for example, the computer
instructions on computer readable media are used to produce the
designs described above. The designs created according to one of
the methods described above are used to produce lenses. Preferably,
the lenses are contact lenses. Illustrative materials for formation
of soft contact lenses include, without limitation, silicone
elastomers, silicone-containing macromers including, without
limitation, those disclosed in U.S. Pat. Nos. 5,371,147, 5,314,960,
and 5,057,578 incorporated in their entireties by reference,
hydrogels, silicone-containing hydrogels, and the like and
combinations thereof. More preferably, the surface is a siloxane,
or contains a siloxane functionality including, without limitation,
polydimethyl siloxane macromers, methacryloxypropyl siloxanes, and
mixtures thereof, silicone hydrogel or a hydrogel. Illustrative
materials include, without limitation, acquafilcon, etafilcon,
genfilcon, lenefilcon, senefilcon, balafilcon, lotrafilcon,
galyfilcon or narafilcon.
[0098] Curing of the lens material may be carried out by any
convenient method. For example, the material may be deposited
within a mold and cured by thermal, irradiation, chemical,
electromagnetic radiation curing and the like and combinations
thereof. Preferably, molding is carried out using ultraviolet light
or using the full spectrum of visible light. More specifically, the
precise conditions suitable for curing the lens material will
depend on the material selected and the lens to be formed. Suitable
processes are disclosed in U.S. Pat. Nos. 4,495,313, 4,680,336,
4,889,664, 5,039,459, and 5,540,410 incorporated herein in their
entireties by reference.
[0099] The contact lenses of the invention may be formed by any
convenient method. One such method uses a lathe to produce mold
inserts. The mold inserts in turn are used to form molds.
Subsequently, a suitable lens material is placed between the molds
followed by compression and curing of the resin to form the lenses
of the invention. One ordinarily skilled in the art will recognize
that any other number of known methods may be used to produce the
lenses of the invention.
EXAMPLES
Example 1
Prophetic
[0100] In a longitudinal study comparing the axial length (eye
growth) and auto-refraction of an age matched pediatric population
of subjects aged 6 to 14 yrs old, contact lenses produced according
to the method and design of the present invention are fitted to one
group while a control group wears conventional contact lenses or
spectacles. The first group receives lenses according to the
following lens design and optical power profile described herein.
[0101] a) The optical power in the central disc of the optic zone
is substantially constant; [0102] b) the optical power in the first
annulus at about a diameter of 4 mm increases in plus power to a
range of +0.5 to +1.5 D, with a preferred value of about +1.0 D, at
a diameter of 6.5 mm increases in plus power to a range +1.5 to
+4.5 D, with a preferred value of about +3.4D; [0103] c) the
optical power in the second annulus decreasing from the power found
at the edge of the first annulus to a power between +1.5 and +4.5
D, with a preferred value of about +3.0 D; [0104] d) the optical
power of the third annulus being substantially constant at about
the power found at the edge of the second annulus.
[0105] The lens powers in this example are described as follows:
[0106] a) The optical power in the central disc of the optic zone
is substantially constant; [0107] b) the optical power in the first
annulus increases in plus power by a suitable polynomial equation
of 4.sup.th order or higher; [0108] c) in a preferred aspect, the
power change in the first annulus is governed by the equation:
Power=0.486x.sup.6-5.8447x.sup.5+27.568x.sup.4-65.028x.sup.3+81.52x.sup.2-
-51.447x+12.773 where x is the radial distance from the center of
the lens. [0109] d) the optical power in the second annulus
decreasing from the power found at the edge of the first annulus to
a power between +1.5 and +4.5 D, with a preferred value of about
+3.0 D; [0110] e) the optical power of the third annulus being
substantially constant at about the power found at the edge of the
second annulus. After six months to one (1) year of the study, the
group wearing the lenses produced by the method and design
according to this invention have a 60% to 80% reduced or a slower
group average rate of eye growth than the group average eye growth
rate of the control group as measured by the change (increase) in
axial length or change (myopic shift) in auto-refraction over the
same time period.
* * * * *