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MULTIFOCAL OPHTHALMIC LENS WITH EXTENDED DEPTH-OF-FOCUS
PRIORITY CLAIM
[0001] This application claims the benefit of priority of
U.S. Provisional Patent
Application Serial No. 63/238,835 titled "MULTIFOCAL OPHTHALMIC LENS WITH
EXTENDED DEPTH-OF-FOCUS," filed on August 31, 2021, whose inventor is Xin
IIong, which is hereby incorporated by reference in its entirety as though
fully and
completely set forth herein.
l'ECHNICAL FIELD
[0002] The disclosure relates generally to a multifocal
ophthalmic lens having an
extended depth-of-focus.
BACKGROUND
[0003] Humans have five basic senses: sight, hearing, smell,
taste, and
touch. Sight gives us the ability to visualize the world around us and
connects us to our
surroundings. Many people worldwide have issues with quality of vision and
require the
use of ophthalmic lenses. For example, as the human eye ages, its ability to
adapt in order
to view objects at different distances declines. An ophthalmic lens may be
worn in front
of the eye and/or may be implanted into the eye. Multifocal lenses are often
used to
provide correction at different focal lengths. However, visual irregularities
may result,
partially due to distinctive defocused images coexisting with sharply focused
images with
a multifocal lens.
SUMMARY
[0004] Disclosed herein is an ophthalmic lens with an optic
having a first surface
and a second surface disposed about an optical axis. At least one of the first
surface and
the second surface includes a surface profile having a base curvature and a
plurality of
zones. The base curvature corresponds to a base optical power. The plurality
of zones is
adapted to produce a plurality of curves corresponding to light energy
distribution along
the optical axis. The surface profile includes a plurality of adjustments
providing an
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extended depth-of-focus, the plurality of adjustments being adapted to extend
each one of
the plurality of curves towards another of the plurality of curves.
100051 The plurality of adjustments may include at least one
spherical aberration.
The plurality of adjustments may include at least one longitudinal chromatic
aberration.
The plurality of adjustments may include at least one phase shift change.
[0006] More generally, in some embodiments, an ophthalmic
lens may include an
optic having a first surface and a second surface disposed about an optical
axis, wherein
at least one of the first surface and the second surface includes a surface
profile having a
base curvature and a plurality of zones_ The base curvature may correspond to
a base
optical power, and the plurality of zones may be adapted to produce a
plurality of curves
corresponding to light energy distribution along the optical axis. The surface
profile may
further include a plurality of adjustments providing an extended depth-of-
focus, the
plurality of adjustments being adapted to extend each one of the plurality of
curves
towards another of the plurality of curves. In some embodiments, the plurality
of
adjustments may include at least one spherical aberration, at least one
longitudinal
chromatic aberration, and/or at least one phase shift change. In some
embodiments, the
plurality of curves may include a near curve, a distance curve, and an
intermediate curve
between the near curve and the distance curve along the optical axis, and the
plurality of
zones may be adapted to produce a near correction via the near curve, a
distance
correction via the distance curve, and an intermediate correction via the
intermediate
curve. In some embodiments, the plurality of adjustments may include a first
adjustment
adapted to extend the distance curve towards the intermediate curve, a second
adjustment
adapted to extend the intermediate curve towards the distance curve, and a
third
adjustment adapted to extend the near curve towards the intermediate curve.
[0007] In further example embodiments, an ophthalmic lens may
include an optic
having a first surface and a second surface disposed about an optical axis,
wherein at least
one of the first surface and the second surface may include a surface profile
having a base
curvature and a plurality of zones. The base curvature may correspond to a
base optical
power, and the plurality of zones may be adapted to produce a near correction
via a near
curve, a distance correction corresponding to the base optical power via a
distance curve,
and an intermediate correction via an intermediate curve between the near
curve and the
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distance curve along the optical axis. The surface profile may further include
a plurality
of adjustments providing an extended depth-of-focus, the plurality of
adjustments
including a first adjustment adapted to extend the distance curve towards the
intermediate
curve, a second adjustment adapted to extend the intermediate curve towards
the distance
curve, and a third adjustment adapted to extend the near curve towards the
intermediate
curve.
[0008] The above features and advantages and other features
and advantages of
the present disclosure are readily apparent from the following detailed
description of the
best modes for carrying out the disclosure when taken in connection with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a schematic sectional view of an ophthalmic
lens with extended
depth-of-focus;
[0010] FIG. 2 is a schematic top view of the ophthalmic lens
of FIG. 1;
[0011] FIG. 3 is a schematic graph of intensity distribution
over distance (along
the optical axis) for an example ophthalmic lens;
[0012] FIG. 4 is a schematic graph of intensity distribution
over distance for the
ophthalmic lens of FIG. 1, with a plurality of adjustments in accordance with
a first
embodiment;
[0013] FIG. 5 is a schematic graph of intensity distribution
over distance for the
ophthalmic lens of FIG. 1, with a plurality of adjustments in accordance with
a second
embodiment;
100141 FIG. 6 is a schematic graph of intensity distribution
over distance for the
ophthalmic lens of FIG. 1, with a plurality of adjustments in accordance with
a third
embodiment;
[0015] FIG. 7 is a schematic fragmentary side view of a
refractive structure that
may be employed in the ophthalmic lens of FIG. 1; and
[0016] FIG. 8 is a schematic fragmentary side view of a
diffractive structure that
may be employed in the ophthalmic lens of FIG. 1.
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DETAILED DESCRIPTION
[0017] Referring to the drawings, wherein like reference
numbers refer to like
components, FIG. 1 schematically illustrates an ophthalmic lens 10 composed of
an optic
12 having a first surface 14 and a second surface 16 disposed about an optical
axis 18.
The first surface 14 may be the anterior surface or the posterior surface.
Conversely, the
second surface 16 may be the posterior surface or the anterior surface. The
ophthalmic
lens 10 is radially symmetric about the optical axis 18. The ophthalmic lens
10 may be an
intraocular lens, a contact lens, a spectacle lens or other type of corrective
lens. As will
be described below, the ophthalmic lens 10 is a multifocal lens that provides
technical
advantages of easier refraction targeting, more continuous vision and fewer
visual
disturbances.
[0018] Referring to FIG. 1, the optic 12 defines a surface
profile 20 having a base
curvature 22 and a plurality of zones 24. The surface profile 20 may be
incorporated on at
least one of the first surface 14 and the second surface 16. FIG. 2 is a
schematic top view
of the ophthalmic lens 10. The plurality of zones 24 may extend between an
inner region
26 and an outer region 28. Referring to FIG. 2, the plurality of zones 24 may
be
structured as respective power regions or annular rings 30 adapted to
differentially
interact with incident light, e.g. via refraction and/or diffraction. The
annular rings 30
may extend from the base curvature 22 (along the Y-axis) with different step
heights,
between a minimum height and a maximum height. The areas of the annular rings
30 may
vary in a controlled manner as a function of distance from the optical axis
18. The
plurality of zones 24 may be adapted to interact with incident light of
different
wavelengths.
100191 Referring to FIG. 1, the base curvature 22 corresponds
to a base optical
power. The shape of the base curvature 22 may be varied and may include a
generally
convex shape, a generally concave shape, a generally plano-concave or a plano-
convex
shape. The base curvature 22 may be different in different zones. The optic 12
may
include one or more structural support members (not shown) and other
components that
are not shown. In one example, the optic 12 is formed from a soft acrylic
material, such
as a copolymer of acrylate and methacrylate, or of hydrogel or silicone. Any
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biocompatible material having a sufficient index of refraction may be employed
to form
the optic 12.
100201 FIGS. 3-6 show graphs of intensity distribution I (on
the vertical axis)
over distance D (on the horizontal axis) along the optical axis 18 for the
ophthalmic lens
10. Referring to FIG. 3, the ophthalmic lens 10 includes a plurality of
adjustments 32
providing an extended depth-of-focus. The plurality of zones 24 of FIGS. 1-2
is adapted
to produce a plurality of curves 34 (see FIG. 3) corresponding to light energy
distribution
along the optical axis 18. In the example shown, the plurality of zones 24 is
adapted to
provide a trifocal correction. In other embodiments, the ophthalmic lens 10
may provide
a bifocal correction. Alternatively, the ophthalmic lens 10 may provide a
quadrifocal
correction.
[0021] Referring to FIG. 3, the plurality of zones 24 (see
FIGS. 1-2) may be
adapted to provide a near correction 40 via an original near curve 42 having a
respective
peak at a first distance D1 on the optical axis 18. An intermediate correction
44 may be
provided via an original intermediate curve 46 having a respective peak at a
second
distance D2. A distance correction 48 may be provided via an original distance
curve 50
having a respective peak at a third distance D3 on the optical axis 18. The
distance
correction 48 may correspond to the base optical power. In a non-limiting
example, the
near correction 40 may correspond to vision at 30-50 cm, and the intermediate
correction
44 may correspond to vision at 50-70 cm. Alternatively, the optic 12 may be
designed for
a non-dominant eye with a base optical power that is slightly less than the
corresponding
distance power, in order to improve overall binocular vision for both eyes.
[0022] Referring to FIG. 3, a plurality of adjustments 32 is
adapted to extend each
one of the plurality of curves 34 towards another of the plurality of curves
34. Referring
to FIG. 3, a first adjustment Al is adapted to extend the original distance
curve 50 to a
modified distance curve 60, in a direction towards the original intermediate
curve 46. A
second adjustment A2 is adapted to extend the original intermediate curve 46
to a
modified intermediate curve 62, in a direction towards the original distance
curve 50.
Referring to FIG. 3, a third adjustment A3 is adapted to extend the original
near curve 42
to a modified near curve 64, in a direction towards the original intermediate
curve 46. As
shown in FIG. 3, the respective peaks of the modified near curve 64, modified
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intermediate curve 62 and modified distance curve 60 may remain at the first
distance
D1, second distance D2 and third distance D3, respectively, along the optical
axis 18.
100231 The ophthalmic lens 10 may be a refractive multifocal.
An example of a
refractive trifocal profile 400 of a refractive structure, having a plurality
of steps 402, is
shown in FIG. 7. The optical step height of each step is the physical height
multiplied by
the difference between the index of refraction of the ophthalmic lens 10 and
the index of
refraction of the surrounding media in which the ophthalmic lens 10 is to be
used.
Referring to FIG. 7, the plurality of steps 402 defines respective power
regions adapted to
refract incident light. It is understood that the physical height, pattern and
spacing of the
plurality of steps 402 may be varied based on the application at hand. In the
example
shown, the first region 404 may provide near correction 40, the second region
406 may
provide intermediate correction 44 and the third region 408 may provide
distance
correction 48.
[0024] The ophthalmic lens 10 may be a diffractive
multifocal. An example of a
diffractive trifocal profile 500, having a plurality of steps 502, is shown in
FIG. 8. As
noted above, the optical step height of each step is the physical height
multiplied by the
difference between the index of refraction of the ophthalmic lens 10 and the
index of
refraction of the surrounding media in which the ophthalmic lens 10 is to be
used. For an
achromatized structure, the optical step height of the steps is greater than
the wavelength
of light and not more than twice the wavelength of light. In other words,
2<zin.H<22,
where H is the physical height of the respective steps, 2 is the wavelength of
light for
which the zone is configured and An is the difference in the index of
refraction. For a
non-achromatized structure, the optical step height of the steps is between 0
and the
wavelength of light, or between O<An.H<X,. It is understood that the physical
height,
pattern and spacing of the plurality of steps 502 may be respectively varied
based on the
application at hand.
[0025] In the example shown, the first region 504 may provide
near correction 40,
second region 506 (having a height HI) may provide intermediate correction 44
and third
region 508 (having a height H2) may provide distance correction 48. In one
example, the
diameters for the annular rings 30 are set by a Fresnel diffractive lens
criteria. The
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diffractive steps may be apodized (gradually declining in step height relative
to a
reference) in order to reduce glare.
100261 The plurality of adjustments 32 of FIG. 3 may be
structured in a number
of ways. FIG. 4 shows a modified distance curve 160, a modified intermediate
curve 162
and a modified near curve 164, in accordance with a first embodiment. In this
embodiment, the first adjustment Al includes a negative spherical aberration,
the second
adj ustment A2 includes a positive spherical aberration, and the third adj
ustment A3
includes a positive spherical aberration. If the ophthalmic lens 10 is a
refractive
multifocal, this may be accomplished by changing the asphericity in the
corresponding
power regions or annular rings 30.
[0027] If the ophthalmic lens 10 is a diffractive multifocal,
the first adjustment
Al (see FIG. 3) may include varying an asphericity of the base curvature 22
(see FIG. 1)
for the distance correction 48 (see FIG. 3). Referring to FIG. 2, the annular
rings 30 may
be adapted to diffract an incident light into a plurality of diffractive
orders defined by
respective polynomials. The second adjustment A2 and the third adjustment A3
may
include varying the respective polynomials of the annular rings 30. In one
example, a
square of the radius (Ri) of a diffractive zone is defined by the following
relation:
24(2i-H1).1f g(i)j, and g(i) = Kai2
Here i is a zone number, is a design wavelength, g(i) is a non-constant
function of i, a is
a first scaling parameter, b is a second scaling parameter, and/ is the focal
length of the
near correction 40 Varying the respective polynomials of the annular rings 30
may
include adjusting the magnitude of one or both of the first scaling parameter
a and the
second scaling parameters b in order to achieve the desired amount of
extension.
100281 The spherical aberration manipulation may be adapted
to have a similar
effect on the near correction 40 and the intermediate correction 44 in a
diffractive
structure, such that the modified near curve 164 of FIG. 4 is similar to the
modified
intermediate curve 162. The surface profile 20 may include a partial aperture
diffractive
structure, with a refractive power compensator incorporated into the base
curvature 22 to
neutralize the base diffractive power.
100291 Referring now to FIG. 5, a modified distance curve
260, a modified
intermediate curve 262 and a modified near curve 264 are shown, in accordance
with a
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second embodiment. In this embodiment, the first adjustment Al includes a
positive
longitudinal chromatic aberration. The second adjustment A2 and the third
adjustment A3
include a respective negative longitudinal chromatic aberration.
[0030] In a diffractive multifocal, this may be achieved by
the negative chromatic
aberration associated with diffractive powers; the higher the diffractive
order, the more
negative the longitudinal chromatic aberration. The distance correction 48
will have a
positive longitudinal chromatic aberration. Referring to FIG. 5, the modified
near curve
264 may be lower and wider than the modified intermediate curve 262 since
there is more
chromatic aberration with higher diffractive orders_ Selection of the
appropriate
diffractive orders for the distance correction 48, intermediate correction 44
and near
correction 40 may be optimized to achieve the desired amounts of extension in
a
particular application. In some embodiments, the first diffractive order is
used for
distance correction 48, the second diffractive order is used for intermediate
correction 44
and the third diffractive order is used for near correction 40. In some
embodiments, the
first diffractive order is used for distance correction 48, while the second
diffractive order
is empty, the third diffractive order is used for intermediate correction 44
and the
fourth diffractive order is used for near correction 40. In other embodiments,
the
first diffractive order is used for distance correction 48, the second
diffractive order may
be used for intermediate correction 44, while the third diffractive order is
empty and the
fourth diffractive order is used for near correction 40. In other embodiments,
different
diffractive orders may be used for different focal ranges.
[0031] Referring now to FIG. 6, a modified distance curve
360, a modified
intermediate curve 362 and a modified near curve 364 are shown, in accordance
with a
third embodiment. In this embodiment, the first adjustment Al includes a
negative phase
shift. The second adjustment A2 and the third adjustment A3 each include a
positive
phase shift. The negative phase shift may correspond to a bounded phase p and
a design
wavelength X, such that -0.5X <p < 0. The positive phase shift may correspond
to the
bounded phase p and the design wavelength X., such that 0 <p < 0.52.
[0032] Referring to FIGS. 1 and 2, the plurality of zones 24
includes respective
power regions or annular rings 30 adapted to interact with incident light. In
the third
embodiment (FIG. 6), if the ophthalmic lens 10 is a refractive multifocal, the
plurality of
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adjustments 32 includes varying respective phase shift step heights in the
respective
power regions. In order to optimize the near correction 40, referring to FIG.
6, the
ophthalmic lens 10 may be adapted such that the modified near curve 364 is
relatively
higher (with a relatively narrower width) than the modified intermediate curve
362.
[0033] In the third embodiment (FIG. 6), if the ophthalmic
lens 10 is a diffractive
multifocal, the plurality of adjustments 32 includes selecting a single or
multiple phase
shift step heights such that it has a negative value when a diffractive order
for distance
correction 48 is considered and respective positive values when diffractive
order for
intermediate correction 44 and near correction 40 is considered. In other
words, the
plurality of adjustments 32 may include varying phase shift step heights to
have a
respective negative value for the modified distance curve 360 and a respective
positive
value for the modified intermediate curve 362 and the modified near curve 364.
[0034]
In summary, the ophthalmic lens 10 provides a broad range of continuous
vision by extending each of a plurality of curves 34 towards another of the
plurality of
curves 34. The ophthalmic lens 10 improves distance refraction targeting by
broadening
the distance correction 48. Additionally, the smoothing of defocused images
and focused
image towards each other minimizes visual disturbances.
[0035] The detailed description and the drawings or figures
are supportive and
descriptive of the disclosure, but the scope of the disclosure is defined
solely by the
claims. While some of the best modes and other embodiments for carrying out
the
claimed disclosure have been described in detail, various alternative designs
and
embodiments exist for practicing the disclosure defined in the appended
claims.
Furthermore, the embodiments shown in the drawings or the characteristics of
various
embodiments mentioned in the present description are not necessarily to be
understood as
embodiments independent of each other. Rather, it is possible that each of the
characteristics described in one of the examples of an embodiment can be
combined with
one or a plurality of other desired characteristics from other embodiments,
resulting in
other embodiments not described in words or by reference to the drawings.
Accordingly,
such other embodiments fall within the framework of the scope of the appended
claims.
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