U.S. patent application number 16/030578 was filed with the patent office on 2018-11-08 for dual-optic intraocular lens that improves overall vision where there is a local loss of retinal function.
The applicant listed for this patent is AMO GRONINGEN B.V.. Invention is credited to Carmen Canovas Vidal, Patricia Ann Piers, Robert Rosen, Dora Sellitri, Marrie Van Der Mooren, Hendrik A. Weeber.
Application Number | 20180318069 16/030578 |
Document ID | / |
Family ID | 53487388 |
Filed Date | 2018-11-08 |
United States Patent
Application |
20180318069 |
Kind Code |
A1 |
Rosen; Robert ; et
al. |
November 8, 2018 |
DUAL-OPTIC INTRAOCULAR LENS THAT IMPROVES OVERALL VISION WHERE
THERE IS A LOCAL LOSS OF RETINAL FUNCTION
Abstract
Systems and methods are provided for improving overall vision in
patients suffering from a loss of vision in a portion of the retina
(e.g., loss of central vision) by providing a dual optic
intraocular lens which redirects and/or focuses light incident on
the eye at oblique angles onto a peripheral retinal location. The
intraocular lens can include a redirection element (e.g., a prism,
a diffractive element, or an optical component with a decentered
GRIN profile) configured to direct incident light along a deflected
optical axis and to focus an image at a location on the peripheral
retina. Optical properties of the intraocular lens can be
configured to improve or reduce peripheral errors at the location
on the peripheral retina. One or more surfaces of the intraocular
lens can be a toric surface, a higher order aspheric surface, an
aspheric Zernike surface or a Biconic Zernike surface to reduce
optical errors in an image produced at a peripheral retinal
location by light incident at oblique angles.
Inventors: |
Rosen; Robert; (Groningen,
NL) ; Weeber; Hendrik A.; (Groningen, NL) ;
Canovas Vidal; Carmen; (Groningen, NL) ; Van Der
Mooren; Marrie; (Engelbert, NL) ; Sellitri; Dora;
(Matera, IT) ; Piers; Patricia Ann; (Groningen,
NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AMO GRONINGEN B.V. |
GRONINGEN |
|
NL |
|
|
Family ID: |
53487388 |
Appl. No.: |
16/030578 |
Filed: |
July 9, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15442452 |
Feb 24, 2017 |
10016270 |
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16030578 |
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14644101 |
Mar 10, 2015 |
9579192 |
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15442452 |
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61987647 |
May 2, 2014 |
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61950757 |
Mar 10, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 3/107 20130101;
A61F 2/1656 20130101; A61F 2240/002 20130101; A61F 2002/1681
20130101; A61F 2/1602 20130101; A61B 3/1005 20130101; A61F 2/1618
20130101; A61B 3/14 20130101; A61F 2/1645 20150401; A61F 2/1637
20130101; A61F 2/1648 20130101; A61F 2/1613 20130101; A61F 2/1659
20130101; A61B 3/103 20130101; A61B 3/0025 20130101; A61F 2/164
20150401; A61B 3/028 20130101; A61F 2/1654 20130101; A61F 2/1605
20150401 |
International
Class: |
A61F 2/16 20060101
A61F002/16; A61B 3/00 20060101 A61B003/00; A61B 3/14 20060101
A61B003/14; A61B 3/107 20060101 A61B003/107; A61B 3/103 20060101
A61B003/103; A61B 3/10 20060101 A61B003/10; A61B 3/028 20060101
A61B003/028 |
Claims
1. An intraocular lens configured to improve vision for a patient's
eye, the intraocular lens (IOL) comprising: a first viewing element
comprising a first surface and a second surface opposite the first
surface; a second viewing element comprising a third surface and a
fourth surface opposite the third surface; and at least one haptic
connected to one of the first or second viewing elements, wherein
the patient's eye is intersected by an optical axis, and the IOL is
configured to improve image quality of an image produced by light
incident on the patient's eye at an oblique angle with respect to
the optical axis and focused at a peripheral retinal location
disposed at a distance from the fovea, and wherein the image
quality is improved by reducing oblique astigmatism at the
peripheral retinal location.
2. The intraocular lens of claim 1, wherein the image quality is
improved by reducing coma at the peripheral retinal location.
3. The intraocular lens of claim 1, wherein the oblique angle is
between about 1 degree and about 25 degrees.
4. The intraocular lens of claim 1, wherein at least one of the
surfaces of the first or second viewing element is a toric surface,
an aspheric surface, a higher order aspheric surface, an aspheric
Zernike surface or a Biconic Zernike surface.
5. The intraocular lens of claim 1, wherein the image has a
modulation transfer function (MTF) of at least 0.3 for a spatial
frequency of 30 cycles/mm for both the tangential and the sagittal
foci at the peripheral retinal location.
6. The intraocular lens of claim 1, wherein the image has a
modulation transfer function (MTF) of at least 0.5 for a spatial
frequency of 100 cycles/mm for both the tangential and the sagittal
foci at the fovea.
7. The intraocular lens of claim 1, wherein the first and second
viewing elements are spaced apart from each other by a distance
between about 0.5 mm and about 3.0 mm.
8. The intraocular lens of claim 1, wherein the first viewing
element provides optical power and the second viewing element
provides correction for optical errors in the image.
9. The intraocular lens of claim 1, wherein one of the first
viewing element or the second viewing element has an optical power
between -5 Diopters and +5 Diopters.
10. The intraocular lens of claim 1, wherein the first and second
viewing elements are configured to be implanted in a capsular bag
of a patient.
11. The intraocular lens of claim 1, wherein the first viewing
element is configured to be implanted in a capsular bag of a
patient's eye and the second viewing elements is configured to be
implanted in the sulcus of the patient's eye.
12. The intraocular lens of claim 1, wherein the first or the
second viewing element includes diffractive features.
13. The intraocular lens of claim 1, wherein the first or the
second viewing element includes prismatic features.
14-26. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit under 35 U.S.C. .sctn.
119(e) of U.S. Provisional Application No. 61/950,757, filed on
Mar. 10, 2014, titled "INTRAOCULAR LENS THAT IMPROVES OVERALL
VISION WHERE THERE IS A LOSS OF CENTRAL VISION." This application
also claims benefit under 35 U.S.C. .sctn. 119(e) of U.S.
Provisional Application No. 61/987,647, filed on May 2, 2014. The
entire content of each of the above identified applications is
incorporated by reference herein in its entirety for all it
discloses and is made part of this specification.
[0002] This application is also related to U.S. application Ser.
No. ______, filed concurrently herewith on Mar. 10, 2015, titled
"INTRAOCULAR LENS THAT IMPROVES OVERALL VISION WHERE THERE IS A
LOCAL LOSS OF RETINAL FUNCTION," Attorney Docket No. AMOLNS.055A4.
This application is also related to U.S. application Ser. No.
______, filed concurrently herewith on Mar. 10, 2015, titled
"ENHANCED TORIC LENS THAT IMPROVES OVERALL VISION WHERE THERE IS A
LOCAL LOSS OF RETINAL FUNCTION," Attorney Docket No. AMOLNS.055A2.
This application is also related to U.S. application Ser. No.
______, filed concurrently herewith on Mar. 10, 2015, titled
"PIGGYBACK INTRAOCULAR LENS THAT IMPROVES OVERALL VISION WHERE
THERE IS A LOCAL LOSS OF RETINAL FUNCTION," Attorney Docket No.
AMOLNS.055A3. The entire content of each of the above identified
applications is incorporated by reference herein in its entirety
for all it discloses and is made part of this specification.
BACKGROUND
Field
[0003] This disclosure generally relates to using an intraocular
lens to improve overall vision where there is a local loss of
retinal function (e.g., loss of central vision due to a central
scotoma), and more particularly to using an intraocular lens to
focus light incident at oblique angles on the patient's eye onto a
location of the peripheral retina.
Description of Related Art
[0004] Surgery on the human eye has become commonplace in recent
years. Many patients pursue eye surgery to treat an adverse eye
condition, such as cataract, myopia and presbyopia. One eye
condition that can be treated surgically is age-related macular
degeneration (AMD). Other retinal disorders affect younger
patients. Examples of such diseases include Stargardt disease and
Best disease. Also, a reverse form of retinitis pigmentosa produces
an initial degradation of central vision. A patient with AMD
suffers from a loss of vision in the central visual field due to
damage to the retina. Patients with AMD rely on their peripheral
vision for accomplishing daily activities. A major cause of AMD is
retinal detachment which can occur due to accumulation of cellular
debris between the retina and the vascular layer of the eye (also
referred to as "choroid") or due to growth of blood vessels from
the choroid behind the retina. In one type of AMD, damage to the
macula can be arrested with the use of medicine and/or laser
treatment if detected early. If the degradation of the retina can
be halted a sustained vision benefit can be obtained with an IOL.
For patients with continued degradation in the retina a vision
benefit is provided at least for a time.
SUMMARY
[0005] The systems, methods and devices of the disclosure each have
several innovative aspects, no single one of which is solely
responsible for the desirable attributes disclosed herein.
[0006] Ophthalmic devices that magnify images on the retina can be
used to improve vision in patients suffering from AMD. Such
ophthalmic devices can include a high optical power loupe or a
telescope. Intraocular lenses (IOLs) that magnify images on the
retina can also be implanted to improve vision in patients
suffering from AMD. Such IOLs are based on a telescopic effect and
can magnify images between about 1.3 times and about 2.5 times,
which will improve resolution at the cost of a reduced visual
field. However, such IOLs may not provide increased contrast
sensitivity.
[0007] Various embodiments disclosed herein include ophthalmic
devices (such as, for example, IOLs, contact lenses, etc.) that
take into consideration the retinal structure and image processing
capabilities of the peripheral retina to improve vision in patients
suffering from AMD. The ophthalmic devices described herein can be
lightweight and compact. Various embodiments of the ophthalmic
devices described herein can focus incident light in a region
around the fovea, such that a patient can move the eye and choose a
direction that provides the best vision. For patients with a
developed preferred area of the peripheral retina, the embodiments
of the ophthalmic devices described herein can focus image at the
preferred area of the peripheral retina as well as correct for
optical errors occurring in the image formed in the area of the
peripheral retina due to optical effects such as oblique
astigmatism and coma. In some patients without a developed
preferred area of peripheral retina, the improvement in the
peripheral vision brought about from correcting the optical errors
in the image formed at a location of the peripheral retina can help
in development of a preferred area of the peripheral retina.
[0008] The embodiments described herein are directed to ophthalmic
lenses, such as an IOL, and a system and method relating to
providing ophthalmic lenses that can improve visual acuity and/or
contrast sensitivity when there is a loss of central vision by
focusing incident light onto an area on the peripheral retina
around the fovea or at a region of the peripheral retina where
vision is best. Such ophthalmic lenses can include spheric/aspheric
refractive surfaces, refractive structures such as prisms and
diffractive structures such as gratings to focus incident light
onto a region of the peripheral retina around the fovea.
[0009] One aspect of the subject matter described in this
disclosure can be implemented in an intraocular lens configured to
improve vision for eyes having no or reduced foveal vision. The
intraocular lens comprises a first zone having an optical axis
which intersects the retina of the eye at a location external to
the fovea; and a second zone having an optical axis which
intersects the retina of the eye at the fovea, wherein the first
zone has a power that is greater than the second zone.
[0010] Another aspect of the subject matter described in this
disclosure can be implemented in a method for improving vision
where there is no or reduced foveal vision using an intraocular
lens with at least two zones. The method comprising: determining a
deflected optical axis which intersects a retina of a user at a
preferred retinal locus; modifying a first zone of the intraocular
lens to redirect incident light along the deflected optical axis;
modifying a second zone of the intraocular lens to direct incident
light along an undeflected optical axis which intersects a retina
of a user at the fovea; and adjusting a power of the first zone to
be greater than a power of the second zone.
[0011] One aspect of the subject matter described in this
disclosure can be implemented in an intraocular lens configured to
improve vision where there is a loss of retinal function (e.g., a
loss of foveal vision), the intraocular lens comprising: a
redirection element configured to redirect incident light along a
deflected optical axis which intersects a retina of a user at a
preferred retinal locus. The redirection element comprises a
surface with a slope profile that is tailored such that, in use,
the intraocular lens: redirects incident light along the deflected
optical axis; focuses the incident light at the preferred retinal
locus; and reduces optical wavefront errors, wherein the slope
profile is tailored to redirect and focus the incoming rays on the
preferred retinal locus. The slope profile can be tailored based at
least in part on a solution to an analytical equation that is a
function of a distance from the IOL vertex to the original focus
(l), an index of refraction of the IOL (n.sub.l), an index of
refraction of the aqueous environment (n.sub.aq), an angle inside
the eye to the preferred retinal locus relative to a back vertex of
the IOL (a.sub.p), a radial position of the IOL (x), and/or the
posterior radius of curvature of the IOL (r), the analytical
equation given by the following:
slope ( x ) = - cos - 1 ( n aq cos .alpha. - n l cos .beta. n aq 2
+ n l 2 - 2 n aq n l sin .alpha. sin .beta. - 2 n aq n l cos
.alpha. cos .beta. ) , ##EQU00001##
wherein
.alpha. = tan - 1 ( l sin a p - x l cos a p - r - r 2 - x 2 ) ,
##EQU00002##
and wherein
.beta. = sin - 1 ( n aq n l sin ( tan - 1 ( - x l - r - r 2 - x 2 )
+ sin - 1 ( x r ) ) ) . ##EQU00003##
In some implementations, the slope profile can be tailored based at
least in part on an analytical solution to an equation describing
an eye of a patient. In some implementations, the slope profile can
be tailored based at least in part on simulations performed using
ray tracing techniques. In some implementations, the slope profile
can be determined analytically using an equation that incorporates
an axial length to the preferred retinal locus, an angle of the
deflected optical axis relative to an undeflected optical axis, and
a radial position of the preferred retinal locus. In various
implementations, the slope profile can be tailored using an
iterative procedure that adjusts a portion of the slope profile to
account for a thickness of the redirection element.
[0012] The redirection element can comprise a plurality of zones.
Each zone can have a slope profile that is tailored based at least
in part on the solution to an equation (e.g., the analytical
equation given above). In various implementations, a thickness of
the redirection element can be less than or equal to 0.5 mm. In
various implementations, a curvature of a posterior surface of the
intraocular lens is configured to provide a focused image at the
fovea of the retina of the patient. In various implementations, the
redirection element can be a separate, additional surface on the
intraocular lens. In some implementations, the redirection element
can be a ring structure. In some implementations, the redirection
element can cover a central portion of the intraocular lens. The
central portion can have a diameter that is greater than or equal
to 1.5 mm and less than or equal to 4.5 mm. In various
implementations, a posterior surface of the intraocular lens can
include the redirection element, and an anterior surface of the
intraocular lens can include a second redirection element
comprising a plurality of zones, each zone having a slope. In some
implementations, a posterior surface and/or an anterior surface of
the intraocular lens can be toric, aspheric, higher order aspheric,
a Zernike surface or some other complex surface. In various
implementations, the posterior surface and/or the anterior surface
of the IOL can be configured to reduce astigmatism and coma in the
focused image produced at the preferred retinal locus. In various
implementations, a portion of the IOL can include the redirection
element and another portion of the IOL can be devoid of the
redirection element. In such implementations, the portion of the
IOL including the redirection element can have an optical power
that is different from the portion of the IOL that is devoid of the
redirection element.
[0013] Another aspect of the subject matter described in this
disclosure can be implemented in a method for improving vision
where there is no or reduced foveal vision using an intraocular
lens and a redirection element having a tailored slope profile. The
method comprising: determining a deflected optical axis which
intersects a retina of a user at a preferred retinal locus;
calculating a tailored slope profile for the redirection element,
the tailored slope profile comprising a plurality of slope values
calculated at a corresponding plurality of points on a surface of
the intraocular lens; determining optical aberrations at the
preferred retinal locus based at least in part on redirecting light
using the redirection element with the tailored slope profile;
adjusting the slope profile to account for a thickness of the
redirection element; and determining whether a quality of an image
produced by the redirection element with the adjusted tailored
slope profile is within a targeted range.
[0014] One aspect of the subject matter described in this
disclosure can be implemented in a method of using an intraocular
lens to improve optical quality at a preferred retinal locus, the
method comprising: obtaining an axial length along an optical axis
from a cornea to a retina; obtaining an axial length along an axis
which deviates from the optical axis and intersects the retina at
the preferred retinal locus. The method further comprises
determining a corneal power based at least in part on measurements
of topography of the cornea; estimating an axial position of the
intraocular lens wherein the intraocular lens with initial optical
properties at the estimated axial position is configured to provide
a focused image at a fovea. The method further comprises adjusting
the initial optical properties of the intraocular lens to provide
adjusted optical properties, the adjusted optical properties based
at least in part on the axial length along the optical axis, the
axial length along the deviated axis to the preferred retinal
locus, and the corneal power, wherein the adjusted optical
properties are configured to reduce peripheral errors at the
preferred retinal location in relation to the intraocular lens with
the initial optical properties.
[0015] Another aspect of the subject matter described in this
disclosure can be implemented in an ophthalmic device configured to
deflect incident light away from the fovea to a desired location of
the peripheral retina. The device comprises an optical lens
including an anterior optical surface configured to receive the
incident light, a posterior optical surface through which incident
light exits the optical lens and an axis intersecting the anterior
surface and posterior surface, the optical lens being rotationally
symmetric about the axis. The device further comprises an optical
component disposed adjacent the anterior or the posterior surface
of the optical lens, the optical component having a surface with a
refractive index profile that is asymmetric about the axis.
[0016] One aspect of the subject matter described in this
disclosure can be implemented in an ophthalmic device comprising an
optical lens including an anterior optical surface configured to
receive the incident light, a posterior optical surface through
which incident light exits the optical lens and an optical axis
intersecting the anterior surface and posterior surface. The device
further comprises an optical component disposed adjacent the
anterior or the posterior surface of the optical lens, the optical
component including a diffractive element, wherein the optical
component is configured to deflect incident light away from the
fovea to a desired location of the peripheral retina.
[0017] One aspect of the subject matter described in this
disclosure can be implemented in an intraocular lens (IOL)
configured to improve vision for a patient's eye. The IOL comprises
a first viewing element comprising a first surface and a second
surface opposite the first surface; a second viewing element
comprising a third surface and a fourth surface opposite the third
surface; and at least one haptic connected to one of the first or
second viewing elements. The IOL is configured to improve image
quality of an image produced by focusing light incident on the
patient's eye (e.g., the cornea) at an oblique angle with respect
to an optical axis that intersects the patient's eye at a
peripheral retinal location disposed at a distance from the fovea.
The image quality is improved by reducing oblique astigmatism at
the peripheral retinal location.
[0018] The image quality can also be improved by reducing coma at
the peripheral retinal location. The oblique angle can be between
about 1 degree and about 25 degrees. The peripheral retinal
location can be disposed at an eccentricity of about 1 degree to
about 25 degrees with respect to the fovea in the horizontal or the
vertical plane. For example, the peripheral retinal location can be
disposed at an eccentricity between about 7 degrees and about 13
degrees in the horizontal plane. As another example, the peripheral
retinal location can be disposed at an eccentricity between about 1
degree and about 10 degrees in the vertical plane. At least one of
the surfaces of the first or second viewing element can be
aspheric. At least one of the surfaces of the first or second
viewing element can be a toric surface, a higher order aspheric
surface, an aspheric Zernike surface or a Biconic Zernike surface.
An image formed by the IOL at the peripheral retinal location can
have a modulation transfer function (MTF) of at least 0.2 (e.g., at
least 0.3, at least 0.4, at least 0.5. at least 0.6, at least 0.7,
at least 0.8, at least 0.9 or values there between) for a spatial
frequency of 30 cycles/mm for both the tangential and the sagittal
foci. An image formed by the IOL at the fovea can have a MTF of at
least 0.2 (e.g., at least 0.3, at least 0.4, at least 0.5. at least
0.6, at least 0.7, at least 0.8, at least 0.9 or values there
between) for a spatial frequency of 100 cycles/mm for both the
tangential and the sagittal foci.
[0019] The first and second viewing elements can be spaced apart
from each other by a distance between about 0.5 mm and about 3.0
mm. In various implementations, one of the first viewing element or
the second viewing element can provide optical power and the other
viewing element can provide correction for optical errors in the
image. One of the first viewing element or the second viewing
element can have an optical power between -5 Diopters and +5
Diopters. The first and second viewing elements can be configured
to be implanted in a capsular bag of a patient. In some
implementations, the first viewing element can be configured to be
implanted in the sulcus and the second viewing elements can be
configured to be implanted in a capsular bag of a patient. In
various implementations, the refractive power provided by the IOL
can vary in response to ocular forces such that the patient can
view objects at different distances. In various implementations,
the change in the refractive power provided by the IOL can be
brought about by configuring the at least one haptic to effect
relative movement between the first and second viewing elements in
response to ocular forces. In various implementations, the first
and/or the second viewing element can include diffractive features,
prismatic features, echelletes etc. to further improve the image
quality at the peripheral retinal location. For example, the first
and/or the second viewing element can include diffractive features
to provide increases depth of focus.
[0020] Another aspect of the subject matter described in this
disclosure can be implemented in a method of designing an
intraocular lens (IOL) configured to be implanted in a patient's
eye. The method comprises determining a surface profile of at least
one of a first surface and a second surface of a first viewing
element; and determining a surface profile of at least one of a
third surface and a fourth surface of a second viewing element. The
surfaces of the first and second viewing elements are determined to
optimize the power of the IOL such that an image produced by
focusing light incident on the patient's eye (e.g., cornea) at an
oblique angle with respect to an optical axis intersecting the
patient's eye at a peripheral retinal location disposed at a
distance from the fovea has reduced optical errors. At least one of
the determined surfaces of the first and/or second viewing element
can be an aspheric surface, a toric surface, a higher order
aspheric surface, an aspheric Zernike surface or a Biconic Zernike
surface.
[0021] The optical power of the IOL that reduces optical errors at
the peripheral retinal location can be obtained from a measurement
of an axial length along an axis which deviates from the optical
axis and intersects the retina at the peripheral retinal location.
The optical power of the IOL that reduces optical errors at the
peripheral retinal location can be obtained from an estimate of an
axial length along an axis which deviates from the optical axis and
intersects the retina at the peripheral retinal location, the
estimate based on measured ocular characteristics of the patient
obtained using a diagnostic instrument. The measured ocular
characteristics can include axial length along the optical axis,
corneal power based at least in part on measurements of topography
of the cornea, pre-operative refractive power and other parameters.
The image produced at the peripheral retinal location can have
reduced peripheral astigmatism and/or coma.
[0022] Another aspect of the subject matter disclosed herein can be
implemented in a method of selecting an intraocular lens (IOL)
configured to be implanted in a patient's eye. The method comprises
obtaining at least one characteristic of the patient's eye using a
diagnostic instrument; and selecting an IOL having an optical power
that reduces optical errors in an image produced at a peripheral
retinal location of the patient's eye disposed at a distance from
the fovea, wherein the IOL is configured to produce an image by
focusing light incident on the patient's eye at an oblique angle
with respect to an optical axis intersecting the patient's eye at
the peripheral retinal location. The optical power of the IOL is
obtained and/or optimized based on the obtained characteristic. The
image can have reduced coma and/or astigmatism. The oblique angle
can be between about 1 degree and about 25 degrees. The IOL can be
configured such that the image has a modulation transfer function
(MTF) of at least 0.3 for a spatial frequency of 30 cycles/mm for
both tangential and sagittal foci.
[0023] The obtained characteristic can include at least one of
axial length along the optical axis of the patient's eye, corneal
power based at least in part on measurements of topography of the
cornea, an axial length along an axis which deviates from the
optical axis and intersects the retina at the peripheral retinal
location, a shape of the retina or a measurement of optical errors
at the peripheral retinal location. In some implementations, the
optical power can be obtained from an estimate of an axial length
along an axis which deviates from the optical axis and intersects
the retina at the peripheral retinal location. The estimate can be
based on the axial length along the optical axis of the patient's
eye and corneal power.
[0024] The IOL can comprise a first viewing element and a second
viewing element. At least one of the surfaces of the first viewing
element or the second viewing element can be a toric surface, an
aspheric surface, a higher order aspheric surface, an aspheric
Zernike surface or a Biconic Zernike surface. At least one of the
surfaces of the first viewing element or the second viewing element
can include a redirecting element. The redirecting element can have
a tailored slope profile as discussed herein. The redirecting
element can include a diffractive feature and/or a prismatic
feature.
[0025] Various implementations disclosed herein are directed
towards an intraocular device (e.g, an intraocular lens, an
ophthalmic solution, a laser ablation pattern, etc.) that improves
visual acuity and contrast sensitivity for patients with central
visual field loss, taking into account visual field, distortion or
magnification of the image. The device can be configured to improve
visual acuity and contrast sensitivity for patients with AMD
through correction of the optical errors for the still healthy
retina that the patient uses for viewing. The device can be
configured to correct peripheral errors of the retina with or
without providing added magnification. The device can be configured
to correct peripheral errors of the retina either without field
loss or in combination with magnification. The device can be
configured to include a near vision zone. The device can be
configured to include multiple optical zones with add power. In
various implementations, wherein the device is configured to focus
light incident in a large patch including a plurality of angles of
incidence is focused in a relatively small area of the retina such
that the image has sufficient contrast sensitivity. In various
implementations, light incident from a plurality of angles of
incidence are focused by the device as an extended horizontal
reading zone above or below the fovea. In various implementations,
light incident from a plurality of angles of incidence are focused
by the device in an area surrounding the fovea and extending up to
the full extent of the peripheral visual field. In various
implementations, the device is configured to provide sufficient
contrast sensitivity for light focused at the fovea for patients
with early stages of macular degeneration.
[0026] Various implementations of the device can include a
redirection element that is configured to redirect incident light
towards a peripheral retinal location. Various implementations of
the device can include symmetric lenses surfaces with aspheric
surfaces. Various implementations of the device can include
asymmetric lenses surfaces with aspheric surfaces. Various
implementations of the device can include asymmetric/symmetric
lenses surfaces with aspheric surfaces having curvatures such that
when implanted in the eye a distance between the anterior surface
of the lens and the pupil is between 2 mm and about 4 mm and the
image formed at a peripheral retinal location at an eccentricity
between 7-13 degrees has an average MTF greater than 0.2 for a
spatial frequency of about 30 cycles/mm. The aspheric surfaces in
various implementations the device can include higher order
aspheric terms. In various implementations, the device can include
a symmetric optical element with a first surface and a second
surface intersected by an optical axis. The thickness of the device
along the optical axis can vary between 0.5 mm and about 2.0 mm.
The first and the second surfaces can be aspheric. In various
implementations, the aspheric surfaces can include higher order
aspheric terms.
[0027] In various implementations, the device can be configured as
a piggyback lens that can be provided in addition to an existing
lens that is configured to provide good foveal vision. The
piggyback lens can be symmetric or asymmetric. The piggyback lens
can be configured to be implanted in the sulcus or in the capsular
bag in front of the existing lens.
[0028] In various implementations, the device can be configured as
a dual optic intraocular lens having a first lens and a second
lens. One or both surfaces of the first and the second lens can be
aspheric. In various implementations, one or both surfaces of the
first and the second lens can include higher order aspheric terms.
In various implementations of the dual optic intraocular lens, the
optic proximal to the closer to the cornea can have a high positive
power and can be configured to be moved either axially in response
to ocular forces to provide accommodation. In various
implementations of the device described herein, the refractive
power provided by optic can be changed in response to ocular
forces. The change in the refractive power can be brought about
through axial movement or change in the shape of the optic. Various
implementations of the device described herein can include a
gradient index lens. One or more surfaces of the optics included in
various implementations of the device described herein can be
diffractive to provide near vision. The optical zones of various
implementations of the device described herein can be split for
different retinal eccentricities.
[0029] Another aspect of the subject matter disclosed herein
includes a power calculation diagnostic procedure that measures
corneal topography, eye length, retinal curvature, peripheral eye
length, pupil position, capsular position, or any combination
thereof in order to determine characteristic of the intraocular
lens device that improves visual acuity and contrast sensitivity
for patients with central visual field loss.
[0030] Implementations of intraocular devices described herein can
include one or more optics with a large optical zone. The
implementations of intraocular devices described herein are
configured to focus obliquely incident light in a location of the
peripheral retina at an eccentricity between about 5-25 degrees
(e.g., eccentricity of 10 degrees, eccentricity of 15 degrees,
eccentricity of 20 degrees, etc.). For patient with a
well-developed preferred retinal location (PRL), various
implementations of the intraocular device can be configured to
focus incident light at the PRL. For patients without a
well-developed PRL, the implementations of intraocular device
described herein can help in the formation of the PRL.
[0031] This disclosure also contemplates the use of diagnostic
devices to determine a region of the peripheral retina which
provides the best vision, determining the power of the intraocular
device at various locations within the region of the peripheral
retina and determining an intraocular device that would correct
optical errors including defocus, astigmatism, coma, spherical
aberration, chromatic aberration (longitudinal and transverse) at
the region of the peripheral retina. When determining the
intraocular device that would correct optical errors at the region
of the peripheral retina, different figures of merit can be used to
characterize the optical performance of different configurations of
the intraocular device and the intraocular device that provides the
best performance can be selected. The different figures of merit
can include MTF at spatial frequencies appropriate for the retinal
areas, weighting of retinal areas, neural weighting, and weighting
of near vision function.
[0032] The methods and systems disclosed herein can also be used to
customize IOLs based on the geometry of a patient's retina, the
extent of retinal degeneration and the geometry and condition of
other structures in the patient's eye. Various embodiments
described herein can also treat other conditions of the eye such as
cataract and correct for presbyopia, myopia and/or astigmatism in
addition to improving visual acuity and/or contrast sensitivity of
peripheral vision.
[0033] The methods and systems described herein to focus incident
light at a region of the peripheral retina around the fovea can
also be applied to spectacle lenses, contact lenses, or ablation
patterns for laser surgeries (e.g., LASIK procedures).
[0034] Details of one or more implementations of the subject matter
described in this specification are set forth in the accompanying
drawings and the description below. Other features, aspects, and
advantages will become apparent from the description, the drawings,
and the claims. Note that the relative dimensions of the following
figures may not be drawn to scale.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Example implementations disclosed herein are illustrated in
the accompanying schematic drawings, which are for illustrative
purposes only.
[0036] FIG. 1 is a diagram illustrating the relevant structures and
distances of the human eye.
[0037] FIG. 2 illustrates different regions of the retina around
the fovea.
[0038] FIG. 3A-3D illustrate simulated vision with a central
scotoma along with ophthalmic device embodiments. A ray diagram
lies to the right of each simulation.
[0039] FIG. 4A is a diagram of an eye implanted with an intraocular
lens that deflects incident light to a preferred retinal location
(PRL). FIG. 4B illustrates an image obtained by a PRL diagnostic
device.
[0040] FIG. 5A illustrates an implementation of a dual optic IOL
that is configured to focus incident light at a location on the
peripheral retina away from the fovea.
[0041] FIG. 5B illustrates another implementation of a dual optic
IOL that is configured to focus incident light at a location on the
peripheral retina away from the fovea. FIG. 5C illustrates an
implementation of a dual optic IOL implanted in a capsular bag.
[0042] FIG. 5D shows a cross-section view of an eye with a central
scotoma at the fovea and implanted with an implementation of an IOL
including the dual optic illustrated in FIG. 5A or FIG. 5B. FIG.
5D-1 and FIG. 5D-2 illustrate regions of peripheral retina where
the IOL illustrated in FIG. 5A or FIG. 5B can improve image
quality. FIG. 5E graphically illustrates the variation in image
quality versus eccentricity for an implementation of an optic
configured to improve image quality at a peripheral retinal
location and an optic configured to improve image quality at the
fovea.
[0043] FIG. 6A shows the surface sag of a first surface of a dual
optic IOL. FIG. 6B shows the surface sag of a second surface of the
dual optic IOL. FIG. 6C shows the surface sag of a third surface of
the dual optic IOL. FIG. 6D shows the surface sag of a fourth
surface of the dual optic IOL.
[0044] FIGS. 7A and 7B show the modulation transfer function for an
implementation of a dual optic IOL having surfaces with surface sag
as shown in FIGS. 6A-6D
[0045] FIG. 8 illustrates a block diagram of an example IOL design
system for determining properties of an intraocular lens configured
to improve overall vision where there is a loss of central
vision.
[0046] FIG. 9 illustrates parameters used to determine an optical
power of an IOL based at least in part on a location of a PRL in a
patient.
[0047] FIG. 10A and FIG. 10B illustrate implementations of a method
for determining an optical power of an IOL tailored to improve
peripheral vision.
[0048] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0049] It is to be understood that the figures and descriptions
have been simplified to illustrate elements that are relevant for a
clear understanding of embodiments described herein, while
eliminating, for the purpose of clarity, many other elements found
in typical lenses, lens systems and lens design methods. Those of
ordinary skill in the arts can recognize that other elements and/or
steps are desirable and may be used in implementing the embodiments
described herein.
[0050] The terms "power" or "optical power" are used herein to
indicate the ability of a lens, an optic, an optical surface, or at
least a portion of an optical surface, to focus incident light for
the purpose of forming a real or virtual focal point. Optical power
may result from reflection, refraction, diffraction, or some
combination thereof and is generally expressed in units of
Diopters. One of ordinary skill in the art will appreciate that the
optical power of a surface, lens, or optic is generally equal to
the refractive index of the medium (n) of the medium that surrounds
the surface, lens, or optic divided by the focal length of the
surface, lens, or optic, when the focal length is expressed in
units of meters.
[0051] The angular ranges that are provided for eccentricity of the
peripheral retinal location in this disclosure refer to the visual
field angle in object space between an object with a corresponding
retinal image on the fovea and an object with a corresponding
retinal image on a peripheral retinal location.
[0052] FIG. 1 is a schematic drawing of a human eye 200. Light
enters the eye from the left of FIG. 1, and passes through the
cornea 210, the anterior chamber 220, a pupil defined by the iris
230, and enters lens 240. After passing through the lens 240, light
passes through the vitreous chamber 250, and strikes the retina,
which detects the light and converts it to a signal transmitted
through the optic nerve to the brain (not shown). The eye 200 is
intersected by an optical axis 280. The optical axis 280 can
correspond to an imaginary line passing through the midpoint of the
visual field to the fovea 260. The visual field can refer to the
area that is visible to the eye in a given position. The cornea 210
has corneal thickness (CT), which is the distance between the
anterior and posterior surfaces of the center of the cornea 210.
The corneal center of curvature 275 can coincide with geometric
center of the eye 200. The anterior chamber 220 has an anterior
chamber depth (ACD), which is the distance between the posterior
surface of the cornea 210 and the anterior surface of the lens 240.
The lens 240 has lens thickness (LT) which is the distance between
the anterior and posterior surfaces of the lens 240. The eye has an
axial length (AXL) which is the distance between the center of the
anterior surface of the cornea 210 and the fovea 260 of the retina,
where the image is focused. The LT and AXL vary in eyes with normal
accommodation depending on whether the eye is focused on near or
far objects.
[0053] The anterior chamber 220 is filled with aqueous humor, and
optically communicates through the lens 240 with the vitreous
chamber 250. The vitreous chamber 250 is filled with vitreous humor
and occupies the largest volume in the eye. The average adult eye
has an ACD of about 3.15 mm, although the ACD typically shallows by
about 0.01 mm per year. Further, the ACD is dependent on the
accommodative state of the lens, i.e., whether the lens 240 is
focusing on an object that is near or far.
[0054] FIG. 2 illustrates different regions of the retina around
the fovea 260. The retina includes a macular region 207. The
macular region 207 has two areas: central and peripheral. Light
focused on the central area contributes to central vision and light
focused on the peripheral area contributes to peripheral vision.
The central region is used to view objects with higher visual
acuity, and the peripheral region is used for viewing large objects
and for capturing information about objects and activities in the
periphery, which are useful for activities involving motion and
detection.
[0055] The macular region 207 is approximately 5.5 mm in diameter.
The center of the macular region 207 is approximately 3.5 mm
lateral to the edge of the optic disc 205 and approximately 1 mm
inferior to the center of the optic disc 205. The shallow
depression in the center of the macula region 207 is the fovea 260.
The fovea 260 has a horizontal dimension (diameter) of
approximately 1.5 mm. The curved wall of the depression gradually
slopes to the floor which is referred to as the foveola 262. The
diameter of the foveola 262 is approximately 0.35 mm. The annular
zone surrounding the fovea 260 can be divided into an inner
parafoveal area 264 and an outer perifoveal area 266. The width of
the parafoveal area 264 is 0.5 mm and of the perifoveal area 266 is
1.5 mm.
[0056] For the general population incident light is focused on the
fovea 260. However, in patients suffering from AMD, a scotoma
develops in the foveal region which leads to a loss in central
vision. Such patients rely on the region of the peripheral retina
around the fovea (e.g., the macular region 207) to view objects.
For example, patients with AMD can focus incident light on the PRL
either by using a magnifying lens that enlarges the image formed on
the retina such that a portion of the image overlaps with a portion
of the peripheral retina around the fovea or by rotating the eye or
the head, thus using eccentric fixation such that light from the
object is incident on the eye (e.g. at the cornea) at oblique
angles and focused on a portion of the peripheral retina around the
fovea. The visual outcome for patients suffering from AMD can be
improved if optical errors resulting from oblique incidence of
light or coma are corrected. In some AMD patients, a portion of the
peripheral retina around the fovea may have has greater visual
acuity and contrast sensitivity compared to other portions of the
peripheral retina. This portion is referred to as the preferred
retinal location (PRL). The visual outcome for such patients may be
improved if incident light were focused at the PRL and the
ophthalmic solutions corrected for optical errors at the PRL. This
is explained in detail below.
[0057] Consider a patient suffering from AMD who desires to view a
smart phone at a normal distance (23 cm simulated here). In such a
patient, the scotoma will block out the view as seen in FIG. 3A.
One solution to improve the visual outcome is to bring the object
of interest closer to the eye. This requires a magnifying glass to
place the object optically at infinity. FIG. 3B illustrates the
simulated view of a smart phone viewed with the aid of a magnifying
glass by a patient with a central scotoma. The effect of the
magnifying glass is to reduce the object distance and enlarge the
size of the image formed on the retina such that it overlaps with a
portion of the peripheral retina around the fovea. For the purpose
of simulations, it is assumed that the magnifying glass is used and
hence the phone is assumed to be at a distance of 7.5 cm. If the
patient has cataract in addition to AMD and is implanted with a
standard IOL, the peripheral errors will increase. FIG. 3C shows
the simulated view of a smart phone viewed by a patient implanted
with a standard IOL and who also suffers from AMD. A comparison of
FIGS. 3B and 3C illustrates that the smart phone screen appears
more blurry when viewed by a patient implanted with a standard IOL
due to the increase in peripheral errors.
[0058] Another solution to improve visual outcome is to utilize
eccentric fixation to focus light from a visual interest on to a
portion of the peripheral retina. FIG. 3D illustrates a simulated
view of a smart phone viewed using eccentric fixation to focus
light from the smart phone screen to a position on the peripheral
retina located about 12.5 degrees away from the fovea. Since, the
image formed at the position on the peripheral retina is formed by
light that is obliquely incident on the eye, optical errors arising
from the oblique incidence of light may degrade the visual quality.
Accordingly, ophthalmic solutions that can correct optical errors
arising from oblique incidence of light may benefit AMD patients
who rely on eccentric fixation to view objects.
[0059] As discussed above, some patients may have a well-developed
PRL and may prefer focusing incident light on the PRL. Such
patients can benefit from an IOL that can focus light at the PRL
instead of the fovea. FIG. 4A is a diagram of the eye 200 implanted
with an IOL 295 that deflects incident light away from the fovea
260 to the PRL 290. For most patients, the PRL 290 is at a distance
less than or equal to about 3.0 mm from the fovea 260. Accordingly,
the IOL 295 can be configured to deflect incident light by an angle
between about 3.0 degrees and up to about 30 degrees such that it
is focused at a preferred location within a region at a distance of
about 3.0 mm around the fovea 260. The IOL 295 can be customized
for a patient by determining the PRL for each patient and then
configuring the IOL 295 to deflect incident light such that it is
focused at the PRL. The method to find the PRL of any patient is
based on Perimetry. One perimetry method to locate the PRL is
Goldmann Perimetry. The perimetry method to locate the PRL includes
measuring the visual field of a patient. For example, the patient
can be asked to fixate on a cross and flashes of lights are
presented at various parts in the field and the responses are
recorded. From the recorded responses, a map of how sensitive the
peripheral retina is can be created. The patient can be trained to
consistently use the healthy and more sensitive portions of the
retina. The perimetry method can be further enhanced by
microperimetry, as used by e.g. the Macular Integrity Assessment
(MAIA) device, where the retina is tracked in order to place the
stimuli consistently and eye movement are accounted for.
[0060] The PRL can also be located subjectively, by asking the
patient to fixate as they want into an OCT-SLO instrument. The
instrument can obtain one or more images of the retina and
determining which portions of retina are used more than the other.
One method of determining the portions of retina that are used more
includes imposing the parts of fixation onto an image of the
retina. The OCT-SILO instrument can also be used to obtain normal
images of the retina. FIG. 4B illustrates an image obtained using
the perimetry method and the fixation method. FIG. 4B shows a photo
of the retina with a central scotoma 415. The red-yellow-orange
dots in the region marked 405 are the results of the perimetry.
Perimetry results indicate that spots closer to the scotoma 415
perform worse that spots farther away from the scotoma 415. The
many small teal dots in the region marked 410 are the fixation
points, and the lighter teal point 420 is the average of the dots
in the region 410. Based on the measurements, the PRL can be
located at either point 420 or one some of the yellow points
425a-425d. Accordingly, an IOL 295 can be configured to focus an
image at one of the points 420 or 425a-425d. The determination of
the PRL for a patient having both cataract and AMD can be made by
methods other than the methods described above.
[0061] Since, AMD patients rely on their peripheral vision to view
objects, their quality of vision can be improved if optical errors
in the peripheral vision are identified and corrected. Optical
power calculation for an IOL configured for foveal vision is based
on measuring eye length and corneal power. However, power
calculation for an IOL that focuses objects in an area around a
peripheral retinal location offset from the fovea can depend on the
curvature of the retina as well as the oblique astigmatism and coma
that is associated with the oblique incidence of light in addition
to the eye length and the corneal power. Optical power calculation
for an IOL that focuses objects in an area around a peripheral
retinal location can also depend on the position of the IOL with
respect to the iris and an axial length along an axis which
deviates from the optical axis and intersects the retina at the
peripheral retinal location
[0062] Methods that are used by an optometrist to measure optical
power for spectacle lenses or contact lenses for non AMD patients
with good foveal vision are not practical for measuring optical
power for ophthalmic solutions (e.g., IOL, spectacle lenses,
contact lenses) for peripheral vision. Optometrists use various
machines such as autorefractors, as well as a method called
subjective refraction wherein the patient reads lines on the wall
chart. The response is then used to gauge which trial lenses to put
in, and the lenses that give the best results are used. However,
such a method is not practical to determine which ophthalmic
solution is best for a patient with AMD who relies on peripheral
vision to view objects since, the performance estimates are
rendered unreliable by the phenomenon of aliasing (a phenomenon
which makes striped shirts look wavy on some television sets with
poor resolution), the difficulty of fixation and general fatigue
associated with orienting the head/eye to focus objects on the
peripheral retina. Instead, the methods used to evaluate the
optical power of ophthalmic solutions for AMD patients rely on
peripheral wavefront sensors to estimate peripheral optical errors.
Peripheral wavefront sensors illuminate a small patch of the PRL
using lasers and evaluate how the light reflected and coming out of
the eye is shaped through an array of micro-lenses. For example, if
the light coming out of the eye is converging, the patient is
myopic at the PRL.
[0063] In various patients suffering from AMD as well as cataract,
the natural lens 240 can be removed and replaced with the IOL 295,
or implanted in the eye 200 in addition to another IOL placed
previously or at the same time as the IOL 295. In some patients
suffering from AMD, the IOL 295 can be implanted in the eye 200 in
addition to the natural lens 240. In FIG. 4A, the IOL 295 is
implanted in the capsular bag. Where possible, the IOL 295 is
placed as close to the retina as possible. However, in other
implementations, the IOL 295 can be implanted within the capsular
bag in front of another IOL or in front of the capsular bag. For
example, the IOL 295 can be configured as an iris, sulcus or
anterior chamber implant or a corneal implant. By selecting an IOL
295 with appropriate refractive properties, the image quality at
the PRL can be improved.
[0064] The visual outcome at a peripheral retinal location is poor
as compared to the foveal visual due to a decreased density of
ganglion cells at the peripheral retinal location and/or optical
errors and artifacts that arise due to oblique incidence of light
(e.g., oblique astigmatism and coma). Patients with AMD can receive
substantial improvement in their vision when optical errors at the
peripheral retinal location are corrected. Many of the existing
embodiments of IOLs that are configured to improve foveal visual
outcome for a patient are not configured to correct for optical
aberrations (e.g., coma, oblique astigmatism, etc.) in the image
generated at the peripheral retinal location.
[0065] It is envisioned that the solutions herein can be applied to
any eccentricity. For example, in some patients, a location that is
disposed at a small angle from the fovea can be used as the PRL
while in some other patients, a location that is disposed at an
angle of about 30 degrees from the fovea can be used as the
PRL.
[0066] Various embodiments of the IOLs disclosed herein are
configured to focus light at a location on the peripheral retina to
produce good quality images, for example, images produced at the
location on the peripheral retina can have a quality that is
substantially similar to the quality of images produced at the
fovea. The images produced at the location on the peripheral retina
by the IOLs disclosed herein can have reduced artifacts from
optical effects such as oblique astigmatism, coma or other higher
order aberrations. Other embodiments are based on the fact that the
location on the peripheral retina is not used in the same way as
the fovea. For example, it may be harder to maintain fixation on
the PRL, so it may be advantageous to increase the area of the
retina where incident light is focused by the IOL in order to have
sufficient visual acuity even when fixation is not maintained
and/or when the eye is moved linearly as in during reading. As
such, the retinal area of interest can cover areas where the
refraction differs substantially due to differences e.g. in retinal
curvature and oblique astigmatism. Various embodiments of IOLs
described herein can be used to direct and/or focus light entering
the eye along different directions at different locations of the
retina. Simulation results and ray diagrams are used to describe
the image forming capabilities of the embodiments described
herein.
[0067] As used herein, an IOL refers to an optical component that
is implanted into the eye of a patient. The IOL comprises an optic,
or clear portion, for focusing light, and may also include one or
more haptics that are attached to the optic and serve to position
the optic in the eye between the pupil and the retina along an
optical axis. In various implementations, the haptic can couple the
optic to zonular fibers of the eye. The optic has an anterior
surface and a posterior surface, each of which can have a
particular shape that contributes to the refractive properties of
the IOL. The optic can be characterized by a shape factor that
depends on the radius of curvature of the anterior and posterior
surfaces and the refractive index of the material of the optic. The
optic can include cylindrical, aspheric, toric, or surfaces with a
slope profile configured to redirect light away from the optical
axis and/or a tight focus.
Dual Optic IOL to Generate an Image at a Location of the Peripheral
Retina for AMD Patients
[0068] FIGS. 5A and 5B depict different implementations of an
intraocular lens (IOL) system 500 which are configured for
implantation into the capsular bag of a patient's eye. In various
implementations, IOL system 500 can be configured such that the
refractive properties of IOL system 500 can be changed in response
to the eye's natural process of accommodation.
[0069] As seen from FIGS. 5A and 5B, the IOL system 500 has a first
viewing element 501 including a haptic 505 and a second viewing
element 503 including a haptic 507. The first viewing element 501
includes a first surface 511a and a second surface 511b. The first
viewing element 501 includes a first optical axis 509a that joins
the center of curvature of the first surface 511a and the center of
curvature of the second surface 511b. The second viewing element
503 includes a third surface 511c and a fourth surface 511d and a
second optical axis 509b that joins the center of curvature of the
third surface 511c and the center of curvature of the fourth
surface 511d. In various implementations, the first optical axis
509a and the second optical axis 509b can coincide with each other
as shown in FIG. 5B. In various implementations, the first optical
axis 509a and the second optical axis 509b can be oriented at an
angle with each and/or horizontally or vertically offset from each
other. Accordingly, the first viewing element 501 and the second
viewing element 503 can be tilted and/or decentered with respect to
each other. Tilting and/or decentering the first viewing element
501 and the second viewing element 503 can be achieved by using
structures and methods described in U.S. Pat. No. 8,062,361 which
is incorporated by reference herein in its entirety. Tilting or
decentering the first viewing element 501 and the second viewing
element 503 can have several advantageous. For example, tilting or
decentering the first viewing element 501 and the second viewing
element 503 can advantageously increase the depth of focus as
discussed in detail in U.S. Pat. No. 8,062,361 which is
incorporated by reference herein in its entirety.
[0070] The first viewing element 501 and the second viewing element
503 can comprise materials that are optical grade and are
biocompatible. For example, one or both the first viewing element
501 and the second viewing element 503 can comprise materials such
as acrylic, silicone, polymethylmethacrylate (PMMA), block
copolymers of styrene-ethylene-butylene-styrene (C-FLEX) or other
styrene-base copolymers, polyvinyl alcohol (PVA), polystyrenes,
polyurethanes, hydrogels, etc. One or both the first viewing
element 501 and the second viewing element 503 can comprise
structures and materials that are described in U.S. Publication No.
2013/0013060 which is incorporated by reference herein in its
entirety. One or both the first viewing element 501 and the second
viewing element 503 can have structural and/or mechanical
properties similar to the structural and/or mechanical properties
of optics described in U.S. Publication No. 2013/0013060 which is
incorporated by reference herein in its entirety. One or both the
first viewing element 501 and the second viewing element 503 can
have optical properties that are described in U.S. Publication No.
2013/0013060 which is incorporated by reference herein in its
entirety. For example, one or both the first viewing element 501
and the second viewing element 503 can have refractive power
between about -25 Diopters and +55 Diopters.
[0071] As another example, the first viewing element 501 can
comprise a lens having a positive power advantageously less than 55
diopters, preferably less than 40 diopters, more preferably less
than 35 diopters, and most preferably less than 30 diopters. The
second viewing element 503 may comprise a lens having a power which
is advantageously between -25 and 0 diopters, and preferably
between -25 and -15 diopters. In various implementations, the first
viewing element 501 and the second viewing element 503 can both
comprise a plano-convex lens. In some implementations, the first
viewing element 501 can comprise a biconvex lens and the second
viewing element 503 can comprise a plano-convex lens. In some
implementations, the first viewing element 501 can comprise a
biconvex lens and the second viewing element 503 can comprise a
convexo-concave lens. Depending on the patient's refractive state
and the degree of AMD, the first viewing element 501 and the second
viewing element 503 can be configured to have either positive
refractive power or negative refractive power. As a further
alternative, one of the viewing elements 501, 503 may comprise a
perimeter frame with an open/empty central portion or void located
on the optical axis, or a perimeter frame member or members with a
zero-power lens or transparent member therein. In still further
variations, one of the viewing elements 501, 503 may comprise only
a zero-power lens or transparent member. As discussed below, the
surfaces 511a, 511b, 511c and 511d of the first viewing element 501
and the second viewing element 503 can include higher order
aspheric terms.
[0072] The haptics 505 and 507 can be configured to hold the first
viewing element 501 and the second viewing element 503 in place.
Accordingly, the haptics 505 and 507 can comprise a biocompatible
material that is suitable to engage the capsular bag of the eye,
the iris 230, the sulcus and/or the ciliary muscles of the eye. For
example, the haptics 505 and/or 507 can comprise materials such as
acrylic, silicone, polymethylmethacrylate (PMMA), block copolymers
of styrene-ethylene-butylene-styrene (C-FLEX) or other styrene-base
copolymers, polyvinyl alcohol (PVA), polystyrene, polyurethanes,
hydrogels, etc. In various implementations, the haptics 505 and 507
can be joined together and form a unitary structure that is
disposed around the periphery of the first viewing element 501 and
the second viewing element 503. For example, the haptic 505 and 507
can be configured to have a structure similar to the structure of
the biasing elements disclosed in U.S. Publication No. 2013/0013060
which is incorporated by reference herein in its entirety. In
various implementations, the haptics 505 and/or 507 can include a
one or more arms that are coupled to the first viewing element 501
and/or the second viewing element 503. In various implementations,
the 505 and/or 507 can include a one or more arms can include one
or more arms that protrude into the first viewing element 501
and/or second viewing element 503.
[0073] The first viewing element 501, the second viewing element
503 and the haptics 505 and 507 may be integrally made of a single
material with or without different characteristics. In various
implementations, the first viewing element 501 and/or the second
viewing element 503 can be made of material from one family and the
haptics 505 and/or 507 can be made of material from another family
(e.g., one from an acrylic family member and the other from a
silicone family member). For example, the first viewing element 501
and/or the second viewing element 503 can be made from a relatively
soft material and configured such that at least a portion of the
optic 42 distorts or changes shape readily in response to ocular
forces generated by the ciliary muscle and/or capsular bag and
transmitted through the haptics 505 and/or 507. The stiffness of
the first viewing element 501 and/or the second viewing element 503
may be less than 500 kPa. For example, the stiffness of the first
viewing element 501 and/or the second viewing element 503 can be
between 0.5 kPa and 500 kPa, between 10 kPa and 200 kPa, between 10
kPa and 50 kPa or between 25 kPa and 50 kPa, or therebetween. The
haptics 505 and/or 507 can be made from a relatively stiff
material, so that it can efficiently transmit the deforming forces
from the ciliary muscles or the capsular bag to the first viewing
element 501 and/or the second viewing element 503. For example, the
haptics 505 and/or 507 may be stiffer than the first viewing
element 501 and/or the second viewing element 503. As another
example, the haptics 505 and/or 507 may be greater than 500 kPa,
greater than 3000 kPa, etc.
[0074] As discussed herein, the IOL system 500 is configured to
focus light incident on the eye (e.g., at the cornea) at oblique
angles to the optical axis 280 of the eye on a location of the
peripheral retina away from the fovea. The IOL system 500 can also
be configured to focus light incident on the eye along a direction
parallel to the optical axis on the fovea for those patients with
early AMD who still have some foveal vision. Additionally, the IOL
system 500 can also be configured to accommodate to focus objects
located at different distances on to the retina (e.g., at a
location on the periphery of the retina and/or the fovea) in
response to ocular forces exerted by the capsular bag and/or
ciliary muscles. For example, the IOL system 500 can be configured
to provide an optical power change between about 0.5 Diopters and
about 6 Diopters in response to ocular forces in the range between
about 1 gram to about 10 grams, 5 to 10 grams, 1 to 5 grams, about
1 to 3 grams or values therebetween.
[0075] An accommodating IOL can provide vision over a broader range
of distances by adjusting its axial position, shape, and/or
thickness in response to ocular forces to effect an optical power
change, similar to the eye's natural lens. The IOL system 500 can
be adapted to be an accommodating IOL by configuring the first
viewing element 501 and/or the second viewing element 503 to adjust
their thickness and/or shape and/or adjust a distance between the
first viewing element 501 and the second viewing element 503 in
response to ocular forces exerted by the capsular bad and/or the
ciliary muscles. In various implementations of the IOL system 500
that is adapted as an accommodating IOL, the first viewing element
501 and/or the second viewing element 503 can be configured to be
moved axially in response to ocular forces exerted by the capsular
bad and/or the ciliary muscles.
[0076] In various implementations of the IOL system 500 that is
adapted to be accommodating, the haptic 505 and/or the haptic 507
can be configured to effect a change of shape or an axial movement
of the first viewing element 501 and the second viewing element
503. For example, the haptics 505 and/or 507 can include springs or
be configured as spring-like members to effect movement of the
first viewing element 505 and/or second viewing element 507 in
response to ocular forces exerted by the capsular bag and/or the
ciliary muscles.
[0077] The IOL system 500 may be integrally formed from a single
piece of material without need to assemble two or more components
(e.g., first/second viewing elements 505/503, haptics 505/507) by
gluing, heat bonding, the use of fasteners or interlocking
elements, etc. This characteristic can advantageously increase the
reliability of the IOL system 500 by improving its resistance to
material fatigue effects which can arise as the lens system
experiences millions of accommodation cycles throughout its service
life. Manufacturing methods such as molding can be used to
monolithically integrate the IOL system 500 using a single piece of
material. Molding process and mold tooling are discussed in detail
in U.S. Publication No. 2013/0013060 which is incorporated by
reference herein in its entirety. Any other suitable technique may
be employed to manufacture single-piece lens systems.
[0078] In various implementations, the IOL system 500 may also be
manufactured by assembling the first viewing element 501, the
second viewing element 503 and the haptics 505/507 by gluing, heat
bonding, the use of fasteners or interlocking elements, etc. In
various implementations, the haptics 505/507 can include one or
more hinges to facilitate the accommodation of the IOL system
500.
[0079] FIG. 5C illustrates an implementation of the IOL system 500
implanted in the eye of a patient. When the IOL system 500 is
implanted, the first viewing element 501 can be configured to be
disposed anteriorly with respect second viewing element 503.
Accordingly, the first viewing element 501 can be disposed such
that the first surface 511a of the first viewing element 501 faces
the cornea and the second viewing element 503 can be disposed such
that the fourth surface 511d of the second viewing element 503
faces the retina. In the illustrated implementation, the IOL system
500 is implanted such that the optical axes 509a and 509b of the
first and second viewing elements 501 and 503 substantially
coincide with each other and the optical axis 280 of the eye.
However, the IOL system 500 can be implanted in the eye such that
the optical axis of only one of the viewing elements coincides with
the optical axis 280 of the eye. Alternately, the IOL system 500
can be implanted in the eye such that the optical axis of neither
of the viewing elements coincides with the optical axis 280 of the
eye. The IOL system 500 can be implanted in the eye such that the
optical axis of one or both the viewing elements is tilted with
respect to the optical axis 280 of the eye. The IOL system 500 can
be implanted in the eye such that the optical axis of one or both
the viewing elements is offset with respect to the optical axis 280
of the eye. In the illustrated implementation, the IOL system 500
is implanted such that both the first and the second viewing
elements 501 and 503 are implanted in the capsular bag of the
patient. However, it is conceived that the IOL system 500 can be
implanted such that the first viewing element 501 is disposed
between the iris and the capsular bag.
[0080] As discussed herein, the IOL system 500 is configured to
focus light incident on the eye at oblique angles with respect to
the optical axis 280 of the eye at a location on the peripheral
retina. The light can be incident in the vertical field of view or
the horizontal field of view. For example, the IOL system 500 can
be configured to focus light incident at oblique angles between
about 5 degrees and about 30 degrees with respect to the optical
axis 280 of the eye, between about 10 degrees and about 25 degrees
with respect to the optical axis 280 of the eye, between about 15
degrees and about 20 degrees with respect to the optical axis 280
of the eye, or there between at a location on the peripheral retina
away from the fovea.
[0081] The IOL system 500 can also be configured such that light
incident on the eye along a direction parallel to the optical axis
is focused on the fovea for those patients with early AMD who still
have some foveal vision. For example, some patients may have parts
of the fovea covered by a scotoma instead of a central scotoma.
Such patients may have some residual foveal vision and can benefit
from incident light being focused at the fovea by the IOL system
500. Additionally, the IOL system 500 can also be configured to
accommodate to focus objects located at different distances on to
the retina (e.g., at a location on the periphery of the retina
and/or the fovea) in response to ocular forces exerted by the
capsular bag and/or ciliary muscles.
[0082] The implementations of the IOL system 500 described in this
disclosure can be configured to correct lower order errors (e.g.
sphere and cylinder), higher order aberrations (e.g., coma,
trefoil) or both resulting from the oblique incidence of light in
the image formed at a location of the peripheral retina. The IOL
system 500 can also configured to correct for peripheral
astigmatism arising from the oblique incidence of light in the
image formed at a location of the peripheral retina. The
characteristic of the surfaces 511a and/or 511b of the first
viewing element 501 and/or the surfaces 511a and/or 511b of the
second viewing element 503, the thickness of the first viewing
element 501, the thickness of the second viewing element 503, the
distance between the first viewing element 501 and the second
viewing element 503, etc. can be designed such that the IOL system
500 can focus light incident on the eye at a plurality of oblique
angles (e.g., between about -25 degree and about +25 degrees with
respect to the optical axis 280 of the eye) in an area around a
location on the peripheral retina spaced away from the fovea with
sufficient visual contrast. This is explained in further detail
below with respect to FIG. 5D.
[0083] FIG. 5D shows a cross-section view of an eye with a central
scotoma at the fovea 260 and implanted with an implementation of an
IOL similar to the IOL system 500 illustrated in FIG. 5A or FIG.
5B. Light from an object is incident in a range of oblique angles
between .theta..sub.1 and .theta..sub.2 with respect to the optical
axis 280 and is focused by the optic 500 in an area 525 disposed
around a location 520 on the peripheral retina disposed away from
the fovea 260. For most patients .theta..sub.1 can be between 1
degree and 5 degrees and .theta..sub.2 can be between 10 degrees
and 35 degrees. The location 520 can be located at a distance r
from the fovea 260 along a direction that makes an angle
.theta..sub.3 with respect to a tangential line 530 intersecting
the retina at the fovea 260 and lying in the vertical plane.
Although, not shown in FIG. 5D, the location 520 can be located at
a distance r from the fovea 260 along a direction that makes an
angle .theta..sub.4 with respect to a tangential line (not shown)
intersecting the retina at the fovea 260 and lying in the
horizontal plane. The angles .theta..sub.3 and .theta..sub.4 can
have a value greater than or equal to 0 degrees and less than 30
degrees. The distance r can have a value between about 0.5 mm and
about 4 mm.
[0084] The area 525 can be described as the region between a first
region which is the base of a cone having a semi angle of
.theta..sub.1 degrees with respect to the optical axis 280 and a
second region which is the base of a cone having a semi angle of
about .theta..sub.2 degrees with respect to the optical axis 280.
Accordingly, the angular width of the area 525 is given by
(.theta..sub.2-.theta..sub.1). For most patients, the angular width
of the area 525 can be between about 5 degrees and about 30
degrees. Without any loss of generality, the area 525 can include
locations that are within about 2-5 mm from the fovea 260. The area
525 can have an angular extent .DELTA..theta..sub.1h in the
horizontal plane and an angular extent .DELTA..theta..sub.1v in the
vertical plane. In various implementations, the angular extent
.DELTA..theta..sub.1v can be zero or substantially small such that
the area 525 is a horizontal line above or below the fovea 260.
Alternately, the angular extent .DELTA..theta..sub.1h can be zero
or substantially small such that the area 525 is a vertical line to
the left or the right of the fovea 260. In some embodiments, the
angular extent .DELTA..theta..sub.1v and the angular extent
.DELTA..theta..sub.1h can be equal such that the area 525 is
circular. In some other implantations, the angular extent
.DELTA..theta..sub.1h and the angular extent .DELTA..theta..sub.1v
can be unequal such that the area 525 is elliptical. In various
implementations, the angular extent .DELTA..theta..sub.1v and the
angular extent .DELTA..theta..sub.1h have values such that the area
525 includes the fovea 260. However, in other implementations, the
angular extent .DELTA..theta..sub.1v and the angular extent
.DELTA..theta..sub.1h can have values such that the area 525 does
not include the fovea 260.
[0085] The IOL system 500 can be symmetric such that the image
quality in an annular region around the fovea is uniform. Such an
IOL system can be used by patients who do not have a well-developed
PRL and who can orient their eyes and/or heads to select the
position that affords the best visual quality. The annular region
can be between a first region and a second region. The first region
can be the base of a cone having a semi angle of .theta..sub.1
degrees with respect to the optical axis 280 and the second region
can be the base of a cone having a semi angle of about
.theta..sub.2 degrees with respect to the optical axis 280.
Accordingly, the angular width of the annular region is given by
(.theta..sub.2-.theta..sub.1). For most patients .theta..sub.1 can
be between 3 degrees and 5 degrees and .theta..sub.2 can be between
10 degrees and 35 degrees. Accordingly, for most patients, the
angular width of the annular region can be between about 5 degrees
and about 30 degrees. Without any loss of generality, the annular
region can include locations that are within about 2-5 mm from the
fovea. Alternately, the IOL system 500 can be asymmetric such that
the image quality is optimized for a certain location of the
peripheral retina (e.g., the PRL). Such an IOL system can be used
by patients who have a well-developed PRL. The PRL can be located
within an annular region around the fovea having an angular width
between about 10-30 degrees. The PRL can be located at a distance
between about 3-5 mm from the fovea. The PRL can be determined
using the methods discussed above with reference to FIG. 4B.
[0086] Generally, patients with AMD experience greater improvement
in their vision when optical errors arising from the oblique
astigmatism and coma are corrected for image formed at a location
in the peripheral retina than patients without AMD at similar
retinal eccentricities. Accordingly, the IOL system 500 is
configured to reduce optical errors at a location on the peripheral
retina due to relative peripheral defocus, oblique astigmatism and
coma. Additionally, the IOL system 500 can also be configured to
provide good image quality at the fovea for those patients who have
early stage AMD. In contrast to optics and IOLs that are configured
to improve image quality at the fovea, the IOL system 500 is
configured to improve image quality in a region of the peripheral
retina that is offset from the fovea. For example, the IOL system
500 can be configured to improve image quality in an annular zone
surrounding the fovea 260 as shown in FIG. 5D-1. The annular zone
can include an area 545 between an inner periphery 535 surrounding
the fovea and an outer periphery 540 surrounding the fovea 260. The
inner periphery 535 can include retinal locations at an
eccentricity between about 1 degree and about 10 degrees. Without
any loss of generality, as used herein, the term eccentricity
refers to the angle between a normal to the retina at the location
of interest and the optical axis of the eye which intersects the
retina at the fovea. Accordingly, the fovea is considered to have
an eccentricity of about 0 degrees. The outer periphery 540 can
include retinal locations at an eccentricity between about 3
degrees and about 25 degrees. Although in FIG. 5D-1 the IOL system
500 is not configured to improve image quality in the foveal
region, in various implementations, the area 545 in which the IOL
system 500 is configured to improve image quality can extend to the
foveal region and include the fovea 260 for patient who have
residual foveal vision. In such implementations, the IOL system 500
can be configured to provide good image quality at the fovea as
well as at peripheral retinal locations at an eccentricity between
about 1 degree and about 25 degrees. In various implementations,
the region 545 can be symmetric about the fovea 260. In some
implementations, a projection of the region 545 on a plane
tangential to the retina at the fovea 260 can be circular, oval or
any other shape.
[0087] As another example, the IOL system 500 can be configured to
improve image quality in a region 548 surrounding a preferred
retinal location (e.g., location 520 as shown in FIG. 5D) offset
from the fovea as shown in FIG. 5D-2. The preferred retinal
location can be located at an eccentricity between about 1 degree
and about 25 degrees. The region 548 surrounding the preferred
retinal location 520 can include retinal locations at an
eccentricity between about 1 degree and about 25 degrees.
[0088] The image quality at the region of the peripheral retina can
be improved by optimizing the image quality produced by the IOL
system 500 such that optical errors (e.g., peripheral astigmatism,
coma, trefoil, etc.) are reduced at the peripheral retinal region.
For example, the image quality at the peripheral retinal region can
be increased by correcting optical errors at the peripheral retinal
region, correcting for corneal astigmatism at the peripheral
retinal region, reducing optical errors resulting from oblique
astigmatism at the peripheral retinal region, reducing coma at the
peripheral retinal region and/or reducing other higher order
aberrations at the peripheral retinal region.
[0089] The improvement in the image quality at the peripheral
retinal region provided by the IOL system 500 can be measured using
different figures of merit discussed below. One figure of merit
that can be used to measured image quality is the modulus of
optical transfer function (MTF) at one or more spatial frequencies
which provides a measure of contrast sensitivity or sharpness. The
MTF for the IOL system 500 is calculated for both sagittal rays and
tangential rays originating from an object disposed with respect to
the intersection of the optic and the optical axis of the eye.
Accordingly, two MTF curves are calculated one for sagittal rays
and the other for tangential rays. For an image to have good
quality and sufficient contrast sensitivity, the MTF for both the
tangential rays and the sagittal rays should be above a threshold.
The MTF is calculated for various off-axis positions of the object
represented by coordinates along the x-direction and the
y-direction in a Cartesian coordinate system in which the point of
intersection of the optic and the optical axis of the eye is
disposed at the origin of the Cartesian coordinate system and the
optical axis is along the z-direction. In various implementations,
the point of intersection of the optic and the optical axis of the
eye can coincide with the geometric of the optic and/or the
geometric center of a surface of the optic.
[0090] The MTF of the IOL system 500 refers to how much of the
contrast ratio in the object is preserved when the object is imaged
by the optic. A MTF of 1.0 indicates that the optic does not
degrade the contrast ratio of the object and MTF of 0 indicates
that the contrast ratio is degraded such that adjacent lines in the
object cannot be resolved when the object is imaged by the optic.
Accordingly, the MTF is a measure of contrast sensitivity or
sharpness. Another figure of merit can include average MTF for a
range of retinal locations and eccentricities, either close to a
single PRL or for multiple PRLs for the patient, and with spatial
frequencies chosen to match the retinal sampling. Other figures of
merit can include area under the MTF curve for different spatial
frequencies, average MTF for a range of spatial frequencies or
combinations of the figures of merit listed here.
[0091] An optic (e.g., the dual optic of the IOL system 500) that
is configured to improve image quality in the peripheral retinal
region can provide a MTF greater than a threshold value
(MTF.sub.THR) at one or more spatial frequencies for an image
produced at the desired peripheral retinal region. Similarly, an
optic that is configured to improve image quality in the foveal
region can provide a MTF greater than a threshold value
(MTF.sub.THR) at one or more spatial frequencies for an image
produced at the foveal region. The threshold value (MTF.sub.THR)
can be subjective and be determined based on the patient's needs
and ophthalmic condition. For example, some patients may be
satisfied with an image quality having a MTF greater than 0.1 for
spatial frequencies between 10 cycles/mm and 50 cycles/mm. Some
other patients may desire a MTF greater than 0.5 for spatial
frequencies between 1 cycle/mm and 100 cycles/mm. Accordingly, the
threshold MTF value (MTF.sub.THR) can vary depending on the lens
design and the patient's needs. The increase in MTF value can be
correlated with an improvement in the patient's ability to read
various lines in an eye chart. For example, without any loss of
generality, an increase in MTF from 0.7 to 0.8 can correspond to
about 15% contrast sensitivity improvement, or 1 line of visual
acuity (VA). Similarly, an increase in MTF from 0.7 to 0.9 can
correspond to about 30% increase in contrast sensitivity or 2 lines
VA.
[0092] FIG. 5E which shows the variation in image quality versus
eccentricity for an implementation of an optic configured to
improve image quality at a peripheral retinal region and an optic
configured to improve image quality at the fovea region. Curve 550
shows the variation of MTF versus eccentricity for an optic
configured to improve image quality at a peripheral retinal region
while curve 555 shows the variation of MTF versus eccentricity for
an optic configured to improve image quality at the foveal region.
As shown in FIG. 5E the optic configured to improve image quality
at a peripheral retinal region provides a MTF greater than a
threshold value (MTF.sub.THR) at one or more spatial frequencies at
an eccentricity between 1 degree and 25 degrees and -1 degree and
-25 degrees such that an image produced in the peripheral retinal
region at an eccentricity between 1 degree and 25 degrees and -1
degree and -25 degrees has sufficient contrast sensitivity. In
various implementations, the optic may be configured to improve
image quality at a peripheral retinal region at the expense of
foveal vision. For example, the optic configured to improve image
quality at a peripheral retinal region may provide a MTF less than
the threshold value (MTF.sub.THR) in the foveal region (e.g., at an
eccentricity between -1 degree and 1 degree). In contrast, an optic
configured to improve foveal vision will provide an MTF greater
than the threshold value (MTF.sub.THR) for an image produced in the
foveal region. In some implementations, the optic configured to
improve image quality at a peripheral retinal region may also be
configured to provide a MTF value greater than the threshold value
(MTF.sub.THR) at the foveal region as shown by curve 560.
[0093] One way to configure the IOL system 500 to reduce optical
errors at a peripheral retinal region is to determine the surfaces
of the first viewing element 501 and/or the second viewing element
503 that reduce optical errors due to oblique astigmatism and coma
at the peripheral retinal region when light incident on the eye
obliquely with respect to the optical axis 280 is focused by the
IOL system 500 at the peripheral retinal region. Using a lens
designing system various surface characteristics of the first,
second, third and/or fourth surface of the first viewing element
501 and/or second viewing element 503 can be determined that reduce
optical errors at a peripheral location of the retina. The various
surface characteristics can include curvatures, surface sags,
radius of curvatures, conic constant, axial thickness, area of the
optical zone, diffractive features, echelletes and/or prismatic
features provided with the optic, etc. In various implementations,
a portion of the first, second, third and/or fourth surface can
include redirecting elements similar to the prismatic features
and/or diffractive features described in U.S. Provisional
Application No. 61/950,757, filed on Mar. 10, 2014, titled
"INTRAOCULAR LENS THAT IMPROVES OVERALL VISION WHERE THERE IS A
LOSS OF CENTRAL VISION," which is incorporated by reference herein
in its entirety. The redirecting elements can be configured to
redirect light incident on the eye along the optical axis and/or at
an angle to the optical axis to one or more locations on the
retina. The surface characteristics can be determined using an eye
model that is based on average population statistics. Alternately,
the surface characteristics can be determined by using an eye model
that is specific to each patient and constructed using a patient's
individual ocular characteristics. Some of the ocular
characteristics that can be taken into consideration when
determining the characteristics of the surfaces of the first
viewing element 501 and the second viewing element 503 can include
corneal radius of curvature and asphericity, axial length, retinal
curvatures, anterior chamber depth, expected lens position,
location of image on the peripheral retina, size of the scotoma,
etc. Depending on the patient's needs, one or more surfaces of the
first viewing element 501 and/or the second viewing element 503 can
be symmetric or asymmetric and/or include higher (e.g., second,
fourth, sixth, eighth) order aspheric terms. For example, one or
more surfaces of the first viewing element 501 and/or the second
viewing element 503 can be parabolic, elliptical, a Zernike
surface, an aspheric Zernike surface, a toric surface, a biconic
Zernike surface, etc.
[0094] FIGS. 6A-6D illustrate the profiles of the various surfaces
for an implementation of a dual optic IOL system 500 that can
reduce optical errors in an image focused at a location on the
peripheral retina. FIG. 6A illustrates the profile of the first
surface 511a of the first viewing element 501. FIG. 6B illustrates
the profile of the second surface 511b of the first viewing element
501. FIG. 6C illustrates the profile of the third surface 511c of
the second viewing element 503. FIG. 6D illustrates the profile of
the fourth surface 511d of the second viewing element 503. It is
noted from FIGS. 6A-6D that all the surfaces for this
implementation of the dual optic IOL system 500 are symmetric and
include aspheric terms. For example, the surfaces of the first and
second viewing elements can include second, fourth, sixth or eighth
order aspheric terms. The surface profiles for other
implementations of dual optic IOL systems can be different from the
profiles illustrated in FIGS. 6A-6D. For example in various
implementations, one or more surfaces of the first and second
viewing elements can be asymmetric with respect to the optical axis
such that the thickness of the first or second viewing element is
not uniform. One or more surfaces of the first and second viewing
elements can have surfaces characteristics that can be described by
mathematical equations including Zernike polynomials and/or
aspheric coefficients. Lenses including aspheric surfaces and other
complex surfaces are also described in U.S. application Ser. No.
______, filed concurrently herewith on Mar. 10, 2015, titled
"INTRAOCULAR LENS THAT IMPROVES OVERALL VISION WHERE THERE IS A
LOCAL LOSS OF RETINAL FUNCTION," Attorney Docket No. AMOLNS.055A4,
which is incorporated by reference herein in its entirety.
Additional implementations of dual optic lenses are also described
in U.S. application Ser. No. ______, filed concurrently herewith on
Mar. 10, 2015, titled "INTRAOCULAR LENS THAT IMPROVES OVERALL
VISION WHERE THERE IS A LOCAL LOSS OF RETINAL FUNCTION," Attorney
Docket No. AMOLNS.055A4, which is incorporated by reference herein
in its entirety. In various implementations, the surfaces of the
first and/or second viewing element 501/503 can be configured to
provide between about 0.5 Diopter and about 6.0 Diopters of
astigmatism.
[0095] The first viewing element 501 and/or the second viewing
element 503 can be configured to provide spherical correction
and/or astigmatic correction. In various implementations, the optic
500 can be multifocal having multiple optical zones configured to
provide a range of add powers between 0.5 Diopter and about 6.0
Diopter. In various implementations, the optic 500 can include
filters and/or coatings to absorb short wavelengths that can damage
the retina further.
[0096] FIGS. 7A and 7B illustrate the optical output from the dual
optic IOL system including surfaces having profiles illustrated in
FIGS. 6A-6D. In particular, FIG. 7A illustrates the modulation
transfer function (MTF) at different locations on the retina
between 7 degrees and 13 degrees with respect to the optical axis
of the eye as a function of spatial frequency. FIG. 7B illustrates
the MTF at the fovea as a function of spatial frequency. The MTF is
calculated (or simulated) for light incident in the horizontal
plane as well as the vertical plane. The MTF can be calculated (or
simulated) using an optical simulation program such as, for
example, OSLO, ZEMAX, CODE V, etc. It is noted from FIG. 7A that
the MTF for different locations on the retina between 7 degrees and
13 degrees with respect to the optical axis of the eye is greater
than 0.5 for spatial frequency up to 30 cycles/mm for both the
tangential and sagittal foci. It is further noted from FIG. 7B that
the dual optic IOL system 500 having surface profiles as shown in
FIGS. 6A-6D can also provide MTF greater than 0.7 spatial frequency
up to 30 cycles/mm at the fovea. Thus, the dual optic IOL system
500 having surface profiles as shown in FIGS. 6A-6D can provide
good vision at a peripheral retinal location between about 7
degrees and about 13 degrees with respect to the optical axis and
at the fovea. Accordingly, such IOL systems can be useful to
patients with AMD with reduced foveal vision as well as patients in
early stages of AMD who have some foveal vision.
[0097] It is conceived that the implementations of dual optic IOLs
that are configured to improve image quality at a peripheral
retinal location by correcting optical errors arising from oblique
incidence of light (e.g., oblique astigmatism and coma) can improve
the MTF by at least 5% (e.g., at least 10% improvement, at least
15% improvement, at least 20% improvement, at least 30%
improvement, etc.) at a spatial frequency of 30 cycles/mm for both
tangential and sagittal foci at a peripheral retinal location at an
eccentricity between about 1 degree and about 25 degrees with
respect to the fovea as compared to the MTF at a spatial frequency
of 30 cycles/mm provided by an IOL that is configured to improve
image quality at the fovea at the same peripheral retinal
location.
[0098] It is conceived that the implementations of dual optic IOLs
that are configured to improve image quality at a peripheral
retinal location by correcting optical errors arising from oblique
incidence of light (e.g., oblique astigmatism and coma) can provide
a MTF greater than 0.2 at a spatial frequency of 30 cycles/mm for
both tangential and sagittal foci, greater than 0.3 at a spatial
frequency of 30 cycles/mm for both tangential and sagittal foci,
greater than 0.4 at a spatial frequency of 30 cycles/mm for both
tangential and sagittal foci, greater than 0.5 at a spatial
frequency of 30 cycles/mm for both tangential and sagittal foci,
greater than 0.6 at a spatial frequency of 30 cycles/mm for both
tangential and sagittal foci, greater than 0.7 at a spatial
frequency of 30 cycles/mm for both tangential and sagittal foci,
greater than 0.8 at a spatial frequency of 30 cycles/mm for both
tangential and sagittal foci or greater than 0.9 at a spatial
frequency of 30 cycles/mm for both tangential and sagittal foci at
a peripheral retinal location between about 1 degree and about 25
degrees with respect to the fovea.
[0099] In various implementations of dual optic IOL systems 500
described herein, the first viewing element 501 can have a
thickness between about 0.5 mm to about 2.0 mm. For example, the
thickness of the first viewing element 501 can be between 0.5 mm
and 0.75 mm, between 0.7 mm and 1.0 mm, between 0.9 mm and 1.3 mm,
between 1.25 mm and 1.5 mm, between 1.4 mm and 1.75 mm, between 1.5
mm and 2.0 mm, or values there between. In various implementations
of dual optic IOL systems 500 described herein, the second viewing
element 503 can have a thickness between about 0.5 mm to about 2.0
mm. For example, the thickness of the first viewing element 501 can
be between 0.5 mm and 0.75 mm, between 0.7 mm and 1.0 mm, between
0.9 mm and 1.3 mm, between 1.25 mm and 1.5 mm, between 1.4 mm and
1.75 mm, between 1.5 mm and 2.0 mm, or values there between. In
various implementations, the thicknesses of the first viewing
element 501 and/or the second viewing element 503 may not be
constant around the optic. As discussed above, in some
implementations, the thickness of the first viewing element 501
and/or the second viewing element 503 can be varied in response to
ocular forces. In various implementations of dual optic IOL systems
500 described herein, the first viewing element 501 can be spaced
apart from the second viewing element 503 by a distance between
about 0.4 mm and 3.0 mm. For example, the distance between the
first viewing element 501 and the second viewing element 503 can be
between 0.4 mm and 0.75 mm, between 0.7 mm and 1.0 mm, between 0.9
mm and 1.3 mm, between 1.25 mm and 1.5 mm, between 1.4 mm and 1.75
mm, between 1.5 mm and 2.0 mm, between 1.9 mm and 2.3 mm, between
2.25 mm and 2.5 mm, between 2.4 mm and 2.8 mm, between 2.75 mm and
3.0 mm or values there between.
[0100] The first viewing element 501 and/or the second viewing
element 503 can have a clear aperture. As used herein, the term
"clear aperture" means the opening of a lens or optic that
restricts the extent of a bundle of light rays from a distant
source that can imaged or focused by the lens or optic. The clear
aperture can be circular and specified by its diameter. Thus, the
clear aperture represents the full extent of the lens or optic
usable for forming the conjugate image of an object or for focusing
light from a distant point source to a single focus or to a
plurality of predetermined foci, in the case of a multifocal optic
or lens. It will be appreciated that the term clear aperture does
not limit the transmittance of the lens or optic to be at or near
100%, but also includes lenses or optics having a lower
transmittance at particular wavelengths or bands of wavelengths at
or near the visible range of the electromagnetic radiation
spectrum. In some embodiments, the clear aperture has the same or
substantially the same diameter as the first or second viewing
element. Alternatively, the diameter of the clear aperture may be
smaller than the diameter of the first or second viewing element.
In various implementations of the dual optic IOL system described
herein the clear aperture of the first viewing element 501 and/or
the second viewing element 503 can have a dimension between about
3.0 mm and about 7.0 mm. For example, the clear aperture of the
first viewing element 501 and/or the second viewing element 503 can
be circular having a diameter of about 5.0 mm in various
implementations of the IOL system 500.
[0101] The first viewing element 501 and/or the second viewing
element 503 can include prismatic, diffractive elements or optical
elements with a gradient refractive index (GRIN) profile to provide
a larger depth of field or near vision capability. The first
viewing element 501 and/or the second viewing element 503 can
include one or more apertures in addition to the clear aperture to
further enhance peripheral image quality. The first viewing element
501 and/or the second viewing element 503 can be configured to
provide magnification in addition to reducing optical errors for
images produced at a peripheral location and/or at the fovea.
[0102] The intraocular lenses described herein can use additional
techniques to extend the depth of focus. For example, the first
and/or second viewing element can include diffractive features
(e.g., optical elements with a GRIN profile, echelletes, etc.) to
increase depth of focus. As another example, in some embodiments, a
refractive power and/or base curvature profile(s) of an intraocular
lens surface(s) may contain additional aspheric terms or an
additional conic constant, which may generate a deliberate amount
of spherical aberration, rather than correct for spherical
aberration. In this manner, light from an object that passes
through the cornea and the lens may have a non-zero spherical
aberration. Because spherical aberration and defocus are related
aberrations, having fourth-order and second-order dependence on
radial pupil coordinate, respectively, introduction of one may be
used to affect the other. Such aspheric surface may be used to
allow the separation between diffraction orders to be modified as
compared to when only spherical refractive surfaces and/or
spherical diffractive base curvatures are used. An additional
number of techniques that increase the depth of focus are described
in detail in U.S. patent application Ser. No. 12/971,506, titled
"SINGLE MICROSTRUCTURE LENS, SYSTEMS AND METHODS," filed on Dec.
17, 2010, and incorporated by reference in its entirety herein. In
some embodiments, a refractive lens may include one or more
surfaces having a pattern of surface deviations that are
superimposed on a base curvature (either spherical or aspheric).
Examples of such lenses, which may be adapted to provide lenses
according to embodiments of the present invention, are disclosed in
U.S. Pat. No. 6,126,286, U.S. Pat. No. 6,923,539 and U.S. Patent
Application No. 2006/0116763, all of which are herein incorporated
by reference in their entirety.
Example IOL Design System
[0103] FIG. 8 illustrates a block diagram of an example IOL design
system 27000 for determining properties of an intraocular lens
configured to improve vision at a peripheral retinal location. The
IOL design system 27000 includes a controller 27050 and a computer
readable memory 27100 coupled to the controller 27050. The computer
readable memory 27100 can include stored sequences of instructions
which, when executed by the controller 27050, cause the IOL design
system 27000 to perform certain functions or execute certain
modules. For example, a PRL location module 27150 can be executed
that is configured to determine a location of one or more PRLs for
a particular patient. As another example, a deflection module 27200
can be executed that is configured to determine a deflected optical
axis which intersects the determined PRL location at the retina. As
another example, an IOL modification module 27250 can be executed
that is configured to determine properties of the IOL which would
deflect at least a portion of incident light along the determined
deflected optical axis to the determined PRL. As another example,
an IOL selection module 27270 can be executed that is configured to
select an appropriate or candidate IOL provided one or more
selection parameters including, for example and without limitation,
PRL location and a patient's biometric data.
[0104] The PRL location module 27150 can be configured to determine
one or more candidate PRL locations using analytical systems and
methods designed to assess retinal sensitivity and/or retinal areas
for fixation. For example, the PRL location module 27150 can
provide or interface with a system configured to provide a patient
with stimuli and to image the patient's retina to assess
topographic retinal sensitivity and locations of preferred retinal
loci. An example of such a system is a microperimeter which can be
used to determine a patient's PRL by presenting a dynamic stimulus
on a screen and imaging the retina with an infrared camera. Another
example of such a system, a laser ophthalmoscope can be used to
assess a retinal area used for fixation (e.g., using an infrared
eye tracker) which can be used to determine discrete retinal areas
for fixation for various positions of gaze.
[0105] The PRL location module 27150 can be configured to bypass
the optics of the patient. In some instances, optical errors
induced by a patient's optics can cause the patient to select a
non-optimal PRL or a PRL which does not exhibit benefits of another
PRL, e.g., where a patient selects an optically superior but
neurally inferior region for the PRL. Accordingly, the PRL location
module 27150 can advantageously allow the identification of a PRL
which, after application of corrective optics (e.g. the IOLs
described herein), would provide superior performance compared to a
PRL selected utilizing a method which includes using the patient's
optics. This may arise where the corrective optics reduce or
eliminate the optical errors which are at least a partial cause for
a patient selecting a sub-optimal PRL.
[0106] The PRL location module 27150 can be configured to determine
multiple candidate locations for the PRL. The preferred or optimal
PRL can be based at least upon several factors including, for
example and without limitation, a patient's ability to fixate a
point target, distinguish detail, and/or read; aberrations arising
from redirecting images to the candidate PRL; proximity to the
damaged portion of the retina; retinal sensitivity at the candidate
location; and the like. The preferred or optimal PRL can depend on
the visual task being performed. For example, a patient can have a
first PRL for reading, a second PRL when navigating, and a third
PRL when talking and doing facial recognition, etc. Accordingly,
multiple PRLs may be appropriate and an IOL can be configured to
redirect incident light to the appropriate PRLs using multiple
zones and/or multiple redirection elements, as described herein.
For example, an IOL can be provided with two or more zones, with
one or more zones redirecting light to a designated PRL, where the
zone can be configured to have additional optical power or no
additional optical power.
[0107] The deflection module 27200 can be configured to assess the
properties of the eye and to determine a deflected optical axis
which intersects the patient's retina at a PRL. The deflection
module 27200 can be configured to account for the removal of the
natural lens, the optical properties of the cornea, the shape of
the retina, the location of the PRL, axial distance from the cornea
to the PRL and the like to determine the angle of deflection from
the eye's natural optical axis (e.g., the optical axis of the
natural lens, the optical axis of the eye without an IOL, etc.). In
some embodiments, the deflection module 27200 can be configured to
determine aberrations arising from deflecting incident light along
the deflected optical axis. The aberrations can include
astigmatism, coma, field curvature, etc. The determined aberrations
can be used in the process of refining or tailoring the design of
the IOL, where the IOL is configured to at least partially correct
or reduce the determined aberrations.
[0108] The IOL modification module 27250 can be configured to
determine adjustments, modifications, or additions to the IOL to
deflect light along the deflected optical axis and focus images on
the PRL. Examples of adjustments, modifications, or additions to
the IOL include, without limitation, the optical systems and
methods described herein. For example, the IOL can be modified
through the introduction of a physical and/or optical discontinuity
to deflect and focus light onto the PRL. As another example, one or
more redirection elements can be added to one or more surfaces of
the IOL to redirect at least a portion of the light incident on the
eye to the PRL. The redirection elements can include, for example
and without limitation, a simple prism, a Fresnel prism, a
redirection element with a tailored slope profile, redirection
element with a tailored slope profile tuned to reduce optical
aberrations, a diffraction grating, a diffraction grating with an
achromatic coating, a decentered GRIN lens, etc. In some
embodiments, multiple redirection elements and/or multiple
modifications can be made to the IOL, as determined by the IOL
modification module 27250, such that the combination of
modifications and/or additions to the IOL can be configured to
redirect incident light to different PRLs, to direct incident light
to different portions of the retina, to provide an optical power
which magnifies an image at the retina, or any combination of these
functions.
[0109] The IOL selection module 27270 can be configured to select
the IOL design, power, deflection, orientation, and the like that
would provide acceptable or optimal results for a particular
patient. The IOL selection can be based at least in part on the
patient's biometric inputs. The IOL selection can incorporate
multiple considerations. For example, typical IOL power calculation
procedures can be used to select the spherical IOL power which can
be modified to consider the axial distance from the cornea to the
PRL. As another example, customized or additional constants can be
developed for AMD patients which provide better results for the
patients. The deflection and orientation of the IOL during
implantation would be given by the PRL location.
[0110] The IOL selection can be based at least in part on ray
tracing which can enable a computational eye model of the patient
to be generated where the inputs can be the patient's own biometric
data. The optical quality can be evaluated considering different
IOL deigns and powers, being selected that which optimizes the
optical quality of the patient. The optical quality can be
evaluated at the PRL or at the PRL and on-axis, for example.
[0111] In some embodiments, the IOL selection module 27270 can also
comprise a refractive planner which shows patients the expected
outcome with different IOL designs and options. This can enable the
patient to aid in the decision as to the appropriate IOL design and
to come to a quick and satisfactory solution.
[0112] The IOL design system 27000 can include a communication bus
27300 configured to allow the various components and modules of the
IOL design system 27000 to communicate with one another and
exchange information. In some embodiments, the communication bus
27300 can include wired and wireless communication within a
computing system or across computing systems, as in a distributed
computing environment. In some embodiments, the communication bus
27300 can at least partially use the Internet to communicate with
the various modules, such as where a module (e.g., any one of
modules 27150, 27200, or 27250) incorporated into an external
computing device and the IOL design system 27000 are communicably
coupled to one another through the communication bus 27300 which
includes a local area network or the Internet.
[0113] The IOL design system 27000 may be a tablet, a general
purpose desktop or laptop computer or may comprise hardware
specifically configured for performing the programmed calculations.
In some embodiments, the IOL design system 27000 is configured to
be electronically coupled to another device such as a
phacoemulsification console or one or more instruments for
obtaining measurements of an eye or a plurality of eyes. In certain
embodiments, the IOL design system 27000 is a handheld device that
may be adapted to be electronically coupled to one of the devices
just listed. In some embodiments, the IOL design system 27000 is,
or is part of, a refractive planner configured to provide one or
more suitable intraocular lenses for implantation based on
physical, structural, and/or geometric characteristics of an eye,
and based on other characteristics of a patient or patient history,
such as the age of a patient, medical history, history of ocular
procedures, life preferences, and the like.
[0114] Generally, the instructions stored on the IOL design system
27000 will include elements of the methods 2900, and/or parameters
and routines for solving the analytical equations discussed herein
as well as iteratively refining optical properties of redirection
elements.
[0115] In certain embodiments, the IOL design system 27000 includes
or is a part of a phacoemulsification system, laser treatment
system, optical diagnostic instrument (e.g, autorefractor,
aberrometer, and/or corneal topographer, or the like). For example,
the computer readable memory 27100 may additionally contain
instructions for controlling the handpiece of a phacoemulsification
system or similar surgical system. Additionally or alternatively,
the computer readable memory 27100 may contain instructions for
controlling or exchanging data with one or more of an
autorefractor, aberrometer, tomographer, microperimeter, laser
ophthalmoscope, topographer, or the like.
[0116] In some embodiments, the IOL design system 27000 includes or
is part of a refractive planner. The refractive planner may be a
system for determining one or more treatment options for a subject
based on such parameters as patient age, family history, vision
preferences (e.g., near, intermediate, distant vision), activity
type/level, past surgical procedures.
[0117] Additionally, the solution can be combined with a
diagnostics system that identifies the best potential PRL after
correction of optical errors. Normally, optical errors can restrict
the patient from employing the best PRL, making them prefer
neurally worse but optically better region. Since this solution
would correct the optical errors, it is important to find the best
PRL of the patient with a method that is not degraded by optical
errors (e.g. adaptive optics). Finally, the solution can be
utilized to take advantage of the symmetries that exists with
regards to peripheral optical errors in many patients.
[0118] Prior to replacing a natural crystalline lens with an IOL,
an optical power of the IOL is typically determined. Generally, the
on-axis axial length, corneal power of the eye, and/or additional
parameters can be used to determine the optical power of the IOL to
achieve a targeted refraction with a goal of providing good or
optimal optical quality for central/foveal vision. However, where
there is a loss of central vision an IOL configured to provide good
or optimal optical quality for central vision may result in
relatively high peripheral refraction and reduced or unacceptable
optical quality at a peripheral location on the retina.
Accordingly, systems and methods provided herein can be used to
tailor the optical power of an IOL to provide good or optimal
optical quality at a targeted peripheral location such as a
patient's PRL. The improvement in optical quality at the peripheral
retinal location may reduce the optical quality at the fovea, but
this may be acceptable where the patient is suffering from a loss
in central vision.
[0119] FIG. 9 illustrates parameters used to determine an optical
power of an IOL based at least in part at a peripheral retinal
location in an eye 2800. The eye 2800 is illustrated with a PRL
location at 20 degrees with respect to the optical axis OA. This
can represent an intended post-operative PRL location, where the
PRL location is determined as described elsewhere herein. The
on-axis axial length (e.g., axial length along optical axis OA) and
PRL-axis axial length (e.g., axial length along a deflected optical
axis intersecting the retina at the PRL) can be measured for the
eye 2800 having the indicated PRL location. In some patients, the
axial length in the direction of the PRL can be estimated from the
measured on-axis axial length and population averages of ocular
characteristics measured using a diagnostic instrument. The ocular
characteristics measured using the diagnostic instrument can
include pre-operative refraction, corneal power or other
parameters. The corneal topography can also be measured (e.g.,
measurements of the anterior and posterior surfaces of the cornea,
thickness of the cornea, etc.) and these measurements can be used,
at least in part, to determine the corneal power.
[0120] FIGS. 10A and 10B illustrate implementations of a method
2900 for determining an optical power of an IOL tailored to improve
peripheral vision. For reference, FIG. 9 provides an illustration
of an eye 2800 for which the method 2900 can be applied. In
addition, FIG. 8 provides a block diagram of the IOL design system
27000 which can perform one or more operations of the method 2900.
The method 2900 can be used to determine the optical power of the
IOL which improves or optimizes optical quality at a PRL location.
However, the method 2900 can be used to determine the optical power
of an IOL to be used in any suitable procedure, such as where there
is a loss of central vision, where the PRL is outside the fovea,
where the PRL is within the fovea, where there are multiple PRLs,
where the PRL is at a relatively large or small eccentricity, or
the like.
[0121] With reference to FIGS. 10A and 10B, in block 2905, the
on-axis axial length is measured. The on-axis axial length can be
measured, for example, from the anterior surface of the cornea to
the retina. The length can be determined using any number of
standard techniques for making measurements of the eye. In some
embodiments, instead of measuring the on-axis axial length, it is
estimated based on computer models of eyes, statistical data (e.g.,
average on-axis distance for eyes with similar characteristics), or
a combination of these. In some embodiments, the on-axis axial
length is determined using a combination of measurement techniques
and estimation techniques.
[0122] With reference to FIG. 10A, in block 2910, the PRL-axis
axial length is measured. The PRL-axis axial length can be taken as
the length along a deflected optical axis to the PRL location at
the retina. The length can be measured from the anterior surface of
the cornea, from the point of deflection from the optical axis, or
any other suitable location. In some embodiments, the PRL-axis
axial length can be estimated based on a combination of the
eccentricity of the PRL, the PRL location, the retinal shape, the
on-axis axial length, the distance from a proposed IOL location to
the PRL, or any combination of these. In some embodiments, instead
of measuring the PRL-axis axial length, it is estimated based on
computer models of eyes, statistical data (e.g., average PRL-axis
axial length for eyes with similar PRL locations and
characteristics), or a combination of these. In some embodiments,
the PRL-axis axial length is determined using a combination of
measurement techniques and estimation techniques. In some
embodiments, the PRL-axis axial length can be estimated based on
population averages of ocular characteristics measured using a
diagnostic instrument, as shown in block 2907 and 2912 of FIG. 10B.
The measured ocular characteristics can include on-axis axial
length, pre-operative refraction power, corneal power or other
measured parameters.
[0123] In block 2915, the corneal shape is determined. The anterior
and/or posterior surfaces of the cornea can be determined using
measurements, estimations, simulations, or any combination of
these. The corneal power can be derived or determined based at
least in part on the corneal shape, that can be measured with
tomography or topographic techniques. In some embodiments, the
corneal power is determined based on measurements of optical
properties of the cornea.
[0124] In block 2920, the position of the IOL is estimated. The
position of the IOL can be estimated based at least in part on an
estimation of a location which would provide good optical quality
at the fovea. The location can be one that takes into account the
corneal power or topography and the on-axis axial length. Some
other inputs that can be taken into consideration to predict the
postoperative IOL position are the axial position of the
crystalline lens from the anterior cornea, which is defined as
anterior chamber depth, crystalline lens thickness, vitreous length
on axis combinations of thereof. In some embodiments, the estimated
position of the IOL can be refined by taking into account the
PRL-axis axial length and/or eccentricity of the PRL. In some
embodiments, the estimated IOL location can take into account data
from previous procedures, with or without including the same IOL
design. For example, historic data from cataract surgeries can be
used as that data may indicate a good estimate of the IOL
position.
[0125] In some embodiments, rather than determining an estimated
initial position of the IOL configured to provide good optical
quality for central/foveal vision, the estimated position can be
configured to provide good optical quality for peripheral vision.
Similar procedures as described for determining the IOL position
that provides with good optical quality on axis can be applied in
this case. Therefore, the location of the IOL can be predicted from
biometric measurements, including corneal shape or power, axial
length, either on axis or to the PRL, anterior chamber depth,
crystalline lens thickens and/or vitreous length, either defined on
axis or to the PRL. Retrospective data from previous cataract
procedures aimed to restore vision on axis or at the PRL can also
been taken into consideration to optimize the prediction of the IOL
position that provide with good optical quality at the PRL. In
addition to that, the estimated position can be based at least in
part on procedures, for example, where the patient was suffering
from central vision loss (e.g., due to AMD). Similarly, data can be
used where the positions of IOLs have been tabulated and recorded
as a function of the properties of the IOLs (e.g., sphere power,
cylinder power, cylinder axis, redirection angle, etc.) and such
properties were tailored using the systems and methods described
herein. Data from such procedures can be subjected to further
selection criteria based on the location of the PRLs of the
patients, where the locations were, for example and without
limitation, outside a determined angular range of the fovea, at an
eccentric angle greater and/or less than a threshold eccentricity,
at an eccentricity within a provided range of the PRL of the
patient, or any combination of these. The data can be selected
based on these criteria or other similar criteria which may improve
the estimated IOL position for patients suffering from a loss of
central vision.
[0126] In block 2925, the sphere and cylinder power of the IOL is
determined using an IOL power calculation. The IOL power
calculation can be configured to provide a spherical power for the
IOL, a cylinder power for the IOL, and/or the cylinder axis,
wherein the combination of one or more of these parameters is
configured to provide good or optimal optical quality at the PRL
location when the IOL is implanted at the estimated location.
[0127] The IOL power calculation can use as input data, for example
and without limitation, on-axis axial length (e.g., the measurement
or value provided in block 2905), corneal power (e.g., the value
determined from measurements acquired in block 2915), fixation
angle(s) (e.g., horizontal and vertical angles of fixation),
intended post-operative refraction, eccentricity of the PRL,
eccentric axial length (e.g., from the anterior cornea to the
location of the PRL on the retina, such as the measurement or value
provided in block 2910), predicted future movement of the PRL
(e.g., due to progression of a disease such as AN/ID), a partial or
full map of the retinal shape, a partial or full map of the retinal
health, corneal topography, or the like. In some embodiments, the
IOL power calculation is a regression formula, a theoretical
formula (e.g., based on paraxial optical equations, ray tracing,
etc.), or a combination of both of these. In some embodiments,
current IOL power calculation procedures can be used while
considering the eccentric axial length together with the corneal
power. In those cases, A constants for either lenses to restore
vision on axis after cataract surgery can be used. In certain
embodiments, specific A constants can be determined depending on
the design and/or eccentricity.
[0128] In some embodiments, ray tracing can be used to determine
properties of the IOL which improve or reduce peripheral errors at
the PRL based at least in part on the estimated IOL position. The
ray tracing can incorporate relevant measurements and data
including, for example and without limitation, the measurements of
the eye (e.g., the measurements or values determined in blocks
2905, 2910, and 2915), the position of the PRL, the estimated
position of the IOL (e.g., as provided in block 2920), and the
like. This information can be used as input in a computer
executable module or program stored in non-transitory computer
memory, the module or program configured to cause a computer
processor to execute instructions configured to perform ray tracing
which can be accomplished, for example, by the IOL design system
27000 described herein with reference to FIG. 8. The ray tracing
system can be used to find the sphere power, cylinder power, and/or
cylinder axis of the IOL to be implanted in the eye 2800, wherein
these parameters are tailored to improve or optimize for peripheral
aberrations at the PRL location. Any standard ray tracing system or
scheme can be used to accomplish the goal of tailoring the sphere
power, cylinder power, and/or cylinder axis.
[0129] In some embodiments, the output of the IOL power calculation
can be used for selecting an appropriate or suitable IOL where the
output of the IOL power calculation includes, for example and
without limitation, dioptric power, cylinder power, cylinder axis,
deflection angle, and the like. These output values can be used in
the selection of the IOL wherein the selected IOL has one or more
properties within an acceptable range of the output values. In some
embodiments, the IOL power calculation can be used to define or
select IOL design parameters that improve or optimize optical
quality as a function of retinal location(s) or retinal
area(s).
[0130] In some embodiments, the IOL power calculation can be
similar or equivalent to a power calculation configured to provide
good or optimal on-axis optical quality (e.g., for central/foveal
vision) where the axial length used is the PRL-axis axial length
rather than the on-axis axial length. In some embodiments, the
PRL-axis axial length can be determined based at least in part on
the eccentricity of the PRL, the PRL location, the retinal shape,
the length from the IOL to the PRL, or any combination of these.
These and other input values can be determined based on
measurements of a particular patient (e.g., the patient to receive
the IOL), a group of patients, from computer models or simulations,
or a combination of these sources. In an alternative embodiment,
both, the axial length on axis and to the PRL can be considered, so
that the IOL selected is that which maximizes the optical quality
at the PRL and at, to some extended, at the fovea. In another
embodiment, the axial length to several PRL can be considered, so
that the IOL selected is that which has the characteristics that
optimize the optical quality at each PRL.
[0131] In some embodiments, the IOL power calculation can be used
for multifocal IOLs for patients suffering from a loss of central
vision. The IOL power calculation can be configured to provide
valid and acceptable results where the PRL lies within the fovea.
In an alternative embodiment the add power of the multifocal IOL
can be selected as that which maximizes the optical quality either
at the PRL and/or the fovea.
[0132] In some embodiments, the IOL power calculation can be used
in conjunction with the other systems and methods described herein
configured to redirect and focus images to the PRL. The power
calculations can be used to tailor the properties of the IOL, the
IOL being used in combination with one or more redirection elements
to reduce peripheral aberrations and/or improve peripheral image
quality for patients suffering from a loss of central vision.
Additional Embodiments for Selecting IOL Sphere and Cylinder
[0133] As detailed above, IOL power is typically selected based
primarily on axial length and corneal power, and any toric parts
mostly depend on the toricity of the cornea. However, any spherical
surface for which the light is obliquely incident will exhibit a
large degree of astigmatism. The embodiments below detail
additional ways to properly select sphere and cylinder of the IOL
for the AMD patient.
[0134] In one embodiment, sphere selection is based on population
data. Here, no new biometry readings are needed. Instead, the
patients are classified depending on foveal refraction, from which
the average peripheral spherical profile for that refractive group
is selected. From the profile, spherical refraction at the PRL can
be determined.
[0135] As seen above, sphere selection may also be based on
individual data. The peripheral sphere can be determined through an
axial length measurement to the PRL. This requires the modification
of current axial length methods, since the oblique incidence on the
crystalline lens will mean a longer than average passage through
the lens, which has a higher index of refraction, increasing the
difference between the optical path length and the physical length.
The increased contribution can be predicted based on PRL
location.
[0136] In one embodiment, astigmatism determination is based on
population data. The inter-subject variation in astigmatism for a
given angle is relatively modest. Therefore, the contribution of
the oblique incidence at any given eccentricity can be predicted
based on PRL location. For these calculations, PRL location should
be determined based on the optical axis, which is on average
between about 1-10 degrees horizontally and between about 1-5
degrees vertically from the fovea. The axis of the astigmatism can
also be determined from the location, e.g. for a horizontal PRL the
axis is 180 and for a vertical PRL the axis is 90, for a negative
cylinder convention. Additionally, the astigmatism contribution of
the IOL selected can be incorporated, in an iterative selection
procedure. To this astigmatism, the corneal astigmatism from the
cornea can also be added.
[0137] In another embodiment, astigmatism determination is based on
individual data. Even for persons that are foveally emmetropic, the
oblique astigmatism at e.g. 20 degrees can vary between 0.75 D and
2 D. There are several possible reasons for this: 1) The individual
differences in angle between fovea and optical axis; 2) Individual
differences in corneal power means the oblique astigmatism has
different values; 3) Pupil position relative lens and cornea can be
different leading to variation in the IOL position for different
individuals. Biometry reading for any or all of these parameters
can then be incorporated into an individual eye model, to select
the best IOL cylinder power for the patient.
CONCLUSION
[0138] The above presents a description of systems and methods
contemplated for carrying out the concepts disclosed herein, and of
the manner and process of making and using it, in such full, clear,
concise, and exact terms as to enable any person skilled in the art
to which it pertains to make and use this invention. The systems
and methods disclosed herein, however, are susceptible to
modifications and alternate constructions from that discussed above
which are within the scope of the present disclosure. Consequently,
it is not the intention to limit this disclosure to the particular
embodiments disclosed. On the contrary, the intention is to cover
modifications and alternate constructions coming within the spirit
and scope of the disclosure as generally expressed by the following
claims, which particularly point out and distinctly claim the
subject matter of embodiments disclosed herein.
[0139] Although embodiments have been described and pictured in an
exemplary form with a certain degree of particularity, it should be
understood that the present disclosure has been made by way of
example, and that numerous changes in the details of construction
and combination and arrangement of parts and steps may be made
without departing from the spirit and scope of the disclosure as
set forth in the claims hereinafter.
[0140] As used herein, the term "controller" or "processor" refers
broadly to any suitable device, logical block, module, circuit, or
combination of elements for executing instructions. For example,
the controller 27050 can include any conventional general purpose
single- or multi-chip microprocessor such as a Pentium.RTM.
processor, a MIPS.RTM. processor, a Power PC.RTM. processor,
AMD.RTM. processor, ARM processor, or an ALPHA.RTM. processor. In
addition, the controller 27050 can include any conventional special
purpose microprocessor such as a digital signal processor. The
various illustrative logical blocks, modules, and circuits
described in connection with the embodiments disclosed herein can
be implemented or performed with a general purpose processor, a
digital signal processor (DSP), an application specific integrated
circuit (ASIC), a field programmable gate array (FPGA), or other
programmable logic device, discrete gate or transistor logic,
discrete hardware components, or any combination thereof designed
to perform the functions described herein. Controller 27050 can be
implemented as a combination of computing devices, e.g., a
combination of a DSP and a microprocessor, a plurality of
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration.
[0141] Computer readable memory 27100 can refer to electronic
circuitry that allows information, typically computer or digital
data, to be stored and retrieved. Computer readable memory 27100
can refer to external devices or systems, for example, disk drives
or solid state drives. Computer readable memory 27100 can also
refer to fast semiconductor storage (chips), for example, Random
Access Memory (RAM) or various forms of Read Only Memory (ROM),
which are directly connected to the communication bus or the
controller 27050. Other types of memory include bubble memory and
core memory. Computer readable memory 27100 can be physical
hardware configured to store information in a non-transitory
medium.
[0142] Methods and processes described herein may be embodied in,
and partially or fully automated via, software code modules
executed by one or more general and/or special purpose computers.
The word "module" can refer to logic embodied in hardware and/or
firmware, or to a collection of software instructions, possibly
having entry and exit points, written in a programming language,
such as, for example, C or C++. A software module may be compiled
and linked into an executable program, installed in a dynamically
linked library, or may be written in an interpreted programming
language such as, for example, BASIC, Perl, or Python. It will be
appreciated that software modules may be callable from other
modules or from themselves, and/or may be invoked in response to
detected events or interrupts. Software instructions may be
embedded in firmware, such as an erasable programmable read-only
memory (EPROM). It will be further appreciated that hardware
modules may comprise connected logic units, such as gates and
flip-flops, and/or may comprised programmable units, such as
programmable gate arrays, application specific integrated circuits,
and/or processors. The modules described herein can be implemented
as software modules, but also may be represented in hardware and/or
firmware. Moreover, although in some embodiments a module may be
separately compiled, in other embodiments a module may represent a
subset of instructions of a separately compiled program, and may
not have an interface available to other logical program units.
[0143] In certain embodiments, code modules may be implemented
and/or stored in any type of computer-readable medium or other
computer storage device. In some systems, data (and/or metadata)
input to the system, data generated by the system, and/or data used
by the system can be stored in any type of computer data
repository, such as a relational database and/or flat file system.
Any of the systems, methods, and processes described herein may
include an interface configured to permit interaction with users,
operators, other systems, components, programs, and so forth.
* * * * *