Patent Description:
The human eye in its simplest terms functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of a lens onto a retina. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea and lens. When age or disease causes the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract. An accepted treatment for this condition is surgical removal of the lens and replacement of the lens with an intraocular lens (IOL).

An IOL typically includes (<NUM>) an optic that corrects the patient's vision (e.g., typically via refraction or diffraction), and (<NUM>) haptics that constitute support structures that hold the optic in place within the patient's eye (e.g., within capsular bag). In general, a physician selects an IOL for which the optic has the appropriate corrective characteristics for the patient. During the surgical procedure, the surgeon may implant the selected IOL by making an incision in the capsular bag of the patient's eye (a capsulorhexis) and inserting the IOL through the incision. Typically, the IOL is folded for insertion into the capsular bag via a corneal incision and unfolded once in place within the capsular bag. During unfolding, the haptics may expand such that a portion of each contacts the capsular bag, retaining the IOL in place.

Although existing IOLs may function acceptably well in many patients, they also have certain shortcomings. For example, existing IOL may have bi-convex optical designs and may be formed of a material having a refractive index that necessitates anterior surface curvatures in a range known to cause reflections. This phenomenon is sometimes referred to a "glint" or "scary eye.

Accordingly, what is needed is an IOL having an optical design that anterior surface curvatures that reduce the incidence of glint across a large range of powers. Reference is made to <CIT>, <CIT>, <CIT> and <CIT> which have been cited as relating to the state of the art. <CIT> for example relates to an intraocular lens having an optical power and a shape factor for implantation in an eye of a patient in which the natural lens has been removed.

It will be appreciated that the scope is in accordance with the claims. Accordingly, there is provided a computer implemented method of manufacturing an intraocular lens as claimed in the independent claim. Further features are provided in the dependent claims. The specification may include further arrangements outside the scope of the claims provided as background and to assist in understanding the invention.

In certain arrangements of the specification, an ophthalmic lens includes an optic having an anterior surface with an anterior surface radius of curvature (R<NUM>) and a posterior surface with a posterior surface radius of curvature (R<NUM>). The anterior surface radius of curvature (R<NUM>) and the posterior surface radius of curvature (R<NUM>) define a shape factor (X) (where X = (R<NUM>-R<NUM>)/(R<NUM>+R<NUM>)) that is greater than zero. The shape factor (X) corresponds to a curve defining shape factor (X) as a function of lens power (P), the curve monotonically decreasing with increased lens power (P).

In certain embodiments, the present disclosure may provide one or more technical advantages. As one example, IOLs having the above-described anterior-biased optical design may reduce the prevalence of "glint," a phenomenon in which an external observer sees a reflection from an IOL implanted in a patient's eye. Human eye model simulations have shown that the intensity of the reflection depends on the anterior surface radius of curvature of the IOL, the intensity of the reflection being strongest in a certain range of radii of curvature that more closely match the curvature of the wavefront incident on the IOL (e.g., radii of curvature in the range of <NUM>-<NUM>). IOLs having the above-described anterior-biased optical design may result in anterior surface radii of curvature across a broad range of IOL powers that are outside the range known to cause the highest intensity reflections, thereby reducing the prevalence of glint.

As another example, IOLs having the above-described anterior-biased optical design may result in a stable effective lens position (ELP) across a broad range of IOL powers due to the fact that the distance between the IOL principal plane and the IOL haptic plane remains substantially constant across the power range. This stability of ELP across the IOL power range may minimize A-constant variation, which may result in better and/or more predictable refractive outcomes.

As yet another example, IOLs having the above-described anterior-biased optical design may be less sensitive to misalignment (e.g., decentration and tilt). More particularly, the above described IOLs have a positive shape factor, meaning they have a relatively high anterior surface curvature. The relatively high anterior surface curvature means that light rays incident on and outgoing from the anterior surface have a small average angle from normal directions such that the Gaussian optics formula deviates from Snell's law by a small amount, decreasing sensitivity to decentration. As a result, IOLs having the above-described anterior-biased optical design may result in better refractive outcomes.

As a final example, IOLs having the above-described anterior-biased optical design may reduce the incidence of negative dysphotopsia post-implantation. One reason for the reduction in the incidence of negative dysphotopsia is that the amount of posterior shift of the iris after cataract surgery may be reduced for IOLs having the above-described anterior-biased optical design. Because it is hypothesized that posterior iris shift may result in the patient experiencing negative dysphotopsia due to light hitting or missing different parts of the retina, reducing such shift may reduce the incidence of negative dysphotopsia. Another reason for the reduction in the incidence of negative dysphotopsia is that peripheral rays (rays entering the patient eye at a high incidence angle) that hit an IOL having the above-described anterior-biased optical design may be spread more evenly as compared to IOLs having an equi-convex design (i.e., same anterior and posterior curvatures). This even spreading of peripheral rays may reduce the perception of negative dysphotopsia.

For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numerals indicate like features and wherein:.

The skilled person in the art will understand that the drawings, described below, are for illustration purposes only. The drawings are not intended to limit the scope of the applicant's disclosure in any way.

In general, the present disclosure relates to an IOL having an anterior-biased optical design, the IOL including an optic having an anterior surface with an anterior surface radius of curvature (R<NUM>) and a posterior surface with a posterior surface radius of curvature (R<NUM>). The anterior surface radius of curvature (R<NUM>) and the posterior surface radius of curvature (R<NUM>) define a shape factor (X) (where X = (R<NUM>-R<NUM>)/(R<NUM>+R<NUM>)) that is greater than zero. The shape factor (X) corresponds to a curve defining shape factor (X) as a function of lens power (P), the curve monotonically decreasing with increased lens power (P).

An IOL having the above-described anterior-biased optical design may reduce the prevalence of glint by maintaining anterior curvatures across a broad range of IOL powers that are outside a range of curvatures known to cause reflections. Additionally, an IOL having the above-described anterior-biased optical design may result in better and/or more predictable refractive outcomes by (<NUM>) providing a substantially constant distance between the IOL principal plane and IOL haptic plane across a broad range of IOL powers, thereby providing stable ELP and reduced A-constant variation across the power range, and (<NUM>) reducing sensitivity to misalignment (e.g., decentration and tilt).

<FIG> illustrate an exemplary ophthalmic lens <NUM> (referred to below as IOL <NUM>) having an optic <NUM> and a plurality of haptics <NUM>. In particular, <FIG> illustrates a top view of IOL <NUM> and <FIG> illustrates a cross-sectional view of the optic 102of the IOL <NUM> (along line A-A of <FIG>).

A variety of techniques and materials can be employed to fabricate the IOL <NUM>. For example, the optic <NUM> of an IOL <NUM> can be formed of a variety of biocompatible polymeric materials. Some suitable biocompatible materials include, without limitation, soft acrylic polymeric materials, hydrogel materials, polymethymethacrylate, or polysulfone, or polystyrene-containing copolymeric materials, or other biocompatible materials. By way of example, in one embodiment, the optic <NUM> may be formed of a soft acrylic hydrophobic copolymer such as those described in <CIT>; <CIT>; <CIT>; or <CIT>. The haptics <NUM> of the IOL <NUM> can also be formed of suitable biocompatible materials, such as those discussed above. While in some cases, the optic <NUM> and haptics <NUM> of an IOL can be fabricated as an integral unit, in other cases they can be formed separately and joined together utilizing techniques known in the art.

Optic <NUM> may include an anterior surface <NUM>, a posterior surface <NUM>, an optical axis <NUM>, and an optic edge <NUM>. Anterior surface <NUM> and/or posterior surface <NUM> may include any suitable surface profiles for correcting a patient's vision. For example, anterior surface <NUM> and/or posterior surface <NUM> may be spheric, aspheric, toric, refractive, diffractive, or any suitable combination thereof. In other words, optic <NUM> may be one or more of a spheric lens, an aspheric lens, a toric lens, a multifocal lens (refractive or diffractive), an extended depth of focus lens, any suitable combination of the foregoing, or any other suitable type of lens.

Anterior surface <NUM> may have an anterior surface diameter <NUM> between <NUM> and <NUM>. In one specific embodiment, anterior surface diameter <NUM> may be approximately <NUM>. Additionally, anterior surface <NUM> may comprise a full surface optic, meaning that the optic portion of anterior surface <NUM> extends to the optic edge <NUM>. Alternatively, anterior surface <NUM> may include one or more transition regions (not depicted) between an edge of the optic region of anterior surface <NUM> and the optic edge <NUM>.

Posterior surface <NUM> may have a posterior surface diameter <NUM> between <NUM> and <NUM>. In one specific embodiment, posterior surface diameter <NUM> may be approximately <NUM> (or may vary, depending on lens power, within a range including <NUM>). Additionally, posterior surface <NUM> may comprise a full surface optic, meaning that the optic portion of posterior surface <NUM> extends to the optic edge <NUM>. Alternatively, posterior surface <NUM> may include one or more transition regions (not depicted) between an edge of the optic region of posterior surface <NUM> and the optic edge <NUM>.

Optic edge <NUM> may extend between anterior surface <NUM> and posterior surface <NUM> and may comprise one or more curved surfaces, one or more flat surfaces, or any suitable combination thereof. In one specific embodiment, optic edge <NUM> may comprise a continuously curved surface extending between anterior surface <NUM> and posterior surface <NUM>. In such embodiments, the continuously curved surface may not include any tangents parallel to optical axis <NUM>, which may advantageously reduce the incidence of positive dysphotopsia results, at least in part, from edge glare.

In certain embodiments, the thickness at optic edge <NUM> may be constant across the entire IOL power range (e.g., <NUM>-<NUM> diopters). As a result, a center thickness of IOL <NUM> (i.e., the thickness along optical axis <NUM>) may vary across the IOL power range. As one example, the thickness at optic edge <NUM> may be approximately <NUM> across the entire IOL power range.

Haptics <NUM> may each include a gusset region <NUM>, an elbow region <NUM>, and a distal region <NUM>. Gusset region <NUM> may extend from the periphery of the optic <NUM> and may span an angle of the periphery of optic <NUM> (e.g. an angle greater than or equal to <NUM> degrees). Elbow region <NUM> may couple gusset region <NUM> and distal region <NUM> and may comprise a portion of the haptic <NUM> having the minimum width (e.g., between <NUM> and <NUM>. As a result, elbow region <NUM> may create a hinge allowing haptic <NUM> to flex while minimizing buckling and vaulting of optic <NUM>. Distal region <NUM> may extend from elbow region <NUM> and may have a length in the range of <NUM> to <NUM>. Although a particular number of haptics <NUM> having a particular configuration are depicted and described, the present disclosure contemplates that IOL <NUM> may include any suitable number of haptics <NUM> having any suitable configuration.

As defined in the claims, anterior surface <NUM> of optic <NUM> has an anterior surface radius of curvature (R<NUM>) and posterior surface <NUM> of optic <NUM> has a posterior surface radius of curvature (R<NUM>). Additionally, the anterior surface radius of curvature (R<NUM>) and the posterior surface radius of curvature (R<NUM>) may collectively define a shape factor (X) for the optic <NUM> as follows: <MAT>.

In addition, anterior surface <NUM> has an anterior surface power (P<NUM>) and posterior surface <NUM> has a posterior surface power (P<NUM>), the anterior and posterior surface powers defined as follows: <MAT> wherein,.

The refractive index of the optic (n<NUM>) may be in a range of <NUM> to <NUM>. In certain embodiments, the refractive index of the optic (n<NUM>) may be in a range of <NUM> to <NUM>. In certain embodiments, the refractive index of the optic (n<NUM>) may be approximately <NUM>.

The shape factor (X) of the optic <NUM> is greater than zero, meaning that the posterior surface radius of curvature (R<NUM>) is greater than the anterior surface radius of curvature (R<NUM>) (i.e., the anterior surface curvature is greater than the posterior surface curvature). In certain embodiments, the shape factor (X) falls in the range of <NUM> to <NUM> for IOLs <NUM> having lens powers (P) in the range of <NUM> to <NUM> diopters.

As defined in the claims, the shape factor (X) corresponds to a curve defining shape factor (X) as a function of lens power (P), the curve monotonically decreasing with increased lens power (P). Due to manufacturing constraints or other manufacturing considerations, the shape factor (X) may not be equal to the value defined by the curve for a given lens power (P). The shape factor (X), however, may nevertheless be selected to correspond to the curve. For example, the shape factor (X) may correspond to the curve in that, for any given lens power (P), the shape factor (X) does not deviate from the curve by more than <NUM>.

As defined in the claims, the above-described curve to which the shape factor (X) corresponds in non-linear. For example, the curve may be defined by the following cubic equation: <MAT> wherein X<NUM>, X<NUM>, X<NUM>, and X<NUM> are constants having values that are real numbers.

In certain embodiments, X<NUM> is in the range of <NUM> to <NUM>, X<NUM> is a negative value in the range of -<NUM> to -<NUM>, X<NUM> is in the range of <NUM> to <NUM>, and X<NUM> is in the range of -. <NUM> to <NUM>. In certain embodiments, X<NUM> is approximately <NUM>, X<NUM> is approximately -<NUM>, X<NUM> is approximately <NUM>, and X<NUM> is approximately -<NUM>.

Given equations (<NUM>) - (<NUM>), the anterior surface radius of curvature (R<NUM>), the posterior surface radius of curvature (R<NUM>), the anterior surface power (P<NUM>), and the posterior surface power (P<NUM>) may be defined as follows: <MAT> <MAT> <MAT> <MAT>.

In embodiments in which the shape factor (X) corresponds to a curve defined by Eq. (<NUM>) and X<NUM> is approximately <NUM>, X<NUM> is approximately -<NUM>, X<NUM> is approximately <NUM>, and X<NUM> is approximately -<NUM>, the curve to which the shape factor (X) corresponds is depicted in <FIG>. As noted above, due to manufacturing constraints or other manufacturing considerations, the shape factor (X) may not be equal to the value defined by the depicted curve for all lens powers (P) but may nevertheless be selected to correspond to the curve (e.g., the shape factor (X) may not deviate from the curve by more than <NUM>).

In embodiments in which optic <NUM> of IOL <NUM> has a refractive index of approximately <NUM> and the shape factor (X) corresponds to the curve depicted in <FIG>, the radius of curvature of the anterior surface (R<NUM>) and the radius of curvature of the posterior surface (R<NUM>) may correspond to the curves depicted in <FIG>. In such embodiments, the anterior surface power (P<NUM>) and the posterior surface power (P<NUM>) may correspond to the curves depicted in <FIG>. Like the variation in shape factor (X) relative to the desired curve discussed above with regard to <FIG>, manufacturing constraints or other manufacturing considerations may necessitate that, for a given lens power (P), the surface radii and/or powers may not be equal to the curves depicted in <FIG>. The surface radii and/or powers, like the shape factor (X), may nevertheless correspond to the curves in that they do not deviate from the curves by more than a certain amount (e.g., the anterior surface radius of curvature (R<NUM>) may not deviate from the curve by more than <NUM>).

In certain embodiments, one or both of the anterior surface <NUM> and the posterior surface may be aspheric. For example, anterior surface <NUM> may be aspheric, with the deviation from the base curvature (i.e., the above-described curvature of anterior surface <NUM>) defined as follows: <MAT> wherein,.

In certain embodiments, the constants of Eq. (<NUM>) (k, a<NUM>, and a<NUM>) may be selected such that a target spherical aberration for IOL <NUM> is achieved. As one example, the constants of Eq. (<NUM>) (k, a<NUM>, and a<NUM>) to achieve a target spherical aberration of <NUM>.

An IOL <NUM> having the above-described anterior-biased optical design (e.g., an IOL <NUM> having shape factors as depicted in <FIG> and anterior and posterior radii of curvature as depicted in <FIG>) may reduce the prevalence of "glint," a phenomenon in which an external observer sees a reflection from an IOL implanted in a patient's eye. Human eye model simulations have shown that the intensity of the reflection depends on the anterior surface radius of curvature of the IOL, the intensity of the reflection being strongest in a certain range of radii of curvature that more closely match the curvature of the wavefront incident on the IOL (e.g., <NUM>-<NUM>). An IOL <NUM> having the above-described anterior-biased optical design may result in anterior surface radii of curvature across a broad range of lens powers (P) (e.g., lens powers (P) in the range of <NUM> to <NUM> diopters) that are outside the range known to cause the highest intensity reflections, thereby reducing the prevalence of glint.

Additionally, an IOL <NUM> having the above-described anterior-biased optical design (e.g., an IOL <NUM> having shape factors (X) corresponding to the curve depicted in <FIG> and anterior/posterior radii of curvature (R<NUM>/R<NUM>) corresponding to the curves depicted in <FIG>) may result in a stable effective lens position (ELP) across a broad range of IOL powers due to the fact that the distance between the IOL principal plane and the IOL haptic plane (ΔPP, described below) remains substantially constant across the power range. This stability of ELP across the IOL power range may minimize A-constant variation, which may result in better and/or more predictable refractive outcomes.

The above-described IOL haptic plane may be defined as a distance (IOLHP) from an apex of the posterior surface as follows: <MAT> wherein,.

The above-described IOL principal plane may be defined as a distance (IOLPP) from an apex of the posterior surface as follows: <MAT> wherein,.

Given Eq. (<NUM>) and Eq. (<NUM>), the distance between the IOL principal plane and the IOL haptic plane (ΔPP) can be defined as follows: <MAT>.

The above-described stability of effective lens position (ELP) is illustrated in <FIG>, which depicts the distance between the IOL haptic plane and IOL principal plane (ΔPP) versus lens power (P) for an IOL <NUM> having shape factors (X) and anterior/posterior radii of curvature (R<NUM>/R<NUM>) as depicted in <FIG> and <FIG> respectively. This is further illustrated by <FIG>, which illustrates the power shift resulting from the distance between the IOL haptic plane and IOL principal plane (ΔPP) plotted in <FIG>. Although <FIG> illustrate ΔPP and corresponding power shift for lenses having shape factors (X) and radii of curvature (R<NUM>/R<NUM>) equal to the curves depicted in <FIG>, the present disclosure contemplates that, due to the above-described deviation of shape factors (X) and radii of curvature (R<NUM>/R<NUM>) from the curves depicted in <FIG> resulting from manufacturing constraints or other manufacturing considerations, there may be corresponding deviation from the curves depicted in <FIG>.

In embodiments in which there is deviation from the curve depicted in <FIG> for the reasons discussed above, the amount of acceptable variation in ΔPP between any two lenses of different lens powers (P) may decrease with increased lens power (P). As just one example, the amount of acceptable variation at various lens powers (P) mat be as follows:.

Additionally, an IOL <NUM> having the above-described anterior-biased optical design (e.g., an IOL <NUM> having shape factors (X) corresponding to the curve depicted in <FIG> and anterior/posterior radii of curvature (R<NUM>/R<NUM>) corresponding to the curves depicted in <FIG>) may be less sensitive to misalignment (e.g., decentration and tilt). More particularly, the above-described IOLs <NUM> have a positive shape factor, meaning they have a relatively high anterior surface curvature. The relatively high anterior surface curvature means that light rays incident on and outgoing from the anterior surface have a small average angle from normal directions such that the Gaussian optics formula deviates from Snell's law by a small amount, decreasing sensitivity to decentration. As a result, IOLs <NUM> having the above-described anterior-biased optical design may result in better refractive outcomes.

Claim 1:
A method of manufacturing an intraocular lens, IOL comprising an optic having an anterior surface and a posterior surface configured to be implanted in a patient's eye, wherein for each lens power (P) in a range of lens powers from <NUM> to <NUM> diopters, the method comprising:
selecting a curvature of the anterior surface, the anterior surface having an anterior surface radius of curvature (R<NUM>) and an anterior surface power (P<NUM>), the anterior surface power defined as: <MAT>
selecting a curvature of the posterior surface, the posterior surface having a posterior surface radius of curvature (R<NUM>) and a posterior surface power (P<NUM>), the posterior surface power defined as: <MAT> wherein:
n<NUM> is a refractive index of aqueous humor of a patient's eye;
n<NUM> is a refractive index of the optic; and
selecting a shape factor (X), wherein the shape factor (X) is defined as: <MAT>
wherein the shape factor (X) is greater than zero and corresponds to a curve defining shape factor (X) as a function of lens power (P), the curve monotonically decreasing with increased lens power (P), wherein the curve is defined by the following cubic equation: X = X<NUM> + X<NUM>P + X<NUM>P<NUM> + X<NUM>P<NUM>;
wherein X<NUM>, X<NUM>, X<NUM>, and X<NUM> are constants having values that are real numbers.