WO2006067255A1

WO2006067255A1 - Intraocular lens for achromatising the eye and reducing the aberrations thereof

Info

Publication number: WO2006067255A1
Application number: PCT/ES2005/070163
Authority: WO
Inventors: Jorge Luciano ALIÓ SANZ; Norberto Lopez Gil; Robert Montes Mico
Original assignee: Instituto Oftalmológico De Alicante, S.L.
Priority date: 2004-12-22
Filing date: 2005-11-29
Publication date: 2006-06-29
Also published as: ES2272143A1; ES2272143B1

Abstract

The invention relates to the use of an intraocular lens (IOL) which is designed to be implanted in a human eye. The inventive lens comprises a first surface (1) and a second surface (2) having different optical properties, one of said surfaces being diffractive and the other refractive. The first (1) and second (2) surfaces define a structure comprising a plurality of optical properties in order to reduce monochromatic spherical aberrations, chromatic aberrations and spherical/chromatic aberrations. According to the invention, the following surfaces can be combined: aspherical diffractive, spherical diffractive, spherical refractive, aspherical refractive. The spherical surfaces can be replaced by flat surfaces.

Description

The Description INTRAOCULAR LENS TO ACROMATIZE THE EYE AND

REDUCE YOUR ABERRATIONS

Field of the Invention

[1] The invention is encompassed within ophthalmology, optometry and optics. Specifically, the invention relates to an intraocular lens to acromatize the eye and reduce its aberrations.

[2]

Background of the Invention

[3] The eye, like other refractive systems, has aberrations that affect the resolution and quality of the image that forms in the retina. The eye suffers from monochromatic aberrations (blur, astigmatism, spherical aberration, and others) and chromatic (longitudinal and transverse). There is a partial correction of spherical aberration by peripheral flattening of the cornea and by the lens, especially in its accommodated state. On the other hand, the eye's optical system does not have the ability to correct chromatic aberration.

[4] Monochromatic aberrations such as blurring and astigmatism can be corrected by ophthalmic lenses, contact lenses, refractive surgery or by implantation of intraocular lenses (IOLs) into the eye.

[5] Monochromatic aberrations such as spherical aberration can also be corrected by ophthalmic and contact lenses and IOL systems are currently beginning to be developed for correction. There are methods to obtain intraocular lenses that provide a reduction in monochromatic aberrations in the eye. U.S. Patent 6,609,793 states a methodology for obtaining aphakic IOLs providing the eye with a reduction in monochromatic aberrations: spherical aberration of high order, blurring and astigmatism. These researchers and others who develop a similar methodology, base their calculations on measurements or simulations performed in monochromatic or quasi-monochromatic light, and suggest eliminating aberration from calculations performed in which intraocular refractive indices remain constant. Said calculation therefore does not take into account the variation of the refractive indices of the media for different wavelengths, that is, the chromatic dispersion of the ocular media.

[6] Chromatic aberration presents an important complication in its correction due to the scattering of light by its very nature and to acromatize the eye, it is usually necessary to couple two or more optical systems (doublets or triplets) for correction. However, IOLs have been devised to achromaticize the eye for the purpose to improve its optical quality. US Patent 5,895,422 and international application WO 94/13225 state an aphakic IOL for the correction of chromatic aberration. These two patents do not consider that the human eye suffers in addition to the chromatic aberration the monochromatic aberrations that have been mentioned previously (example: spherical aberration), and the change of this spherical aberration with the light scattering (spherochromatic aberration), which greatly reduce the quality of the image that forms on the retina.

[7] In the eye, other problems also occur, such as cataracts. Cataract is the loss of transparency of the lens. The lens is a transparent lens that we have behind the pupil and that helps us sharply focus on the objects. Over the years, due to trauma, disease, the lens may lose its natural transparency. The treatment of cataracts is fundamentally surgical. The cataract operation consists of the extraction of the lens that is opacified and its replacement by an artificial lens: IOL, which is placed in the same place as the original lens, restoring the vision that had been lost as a result of the cataracts (Agarwal S et al. in Phacoemulsification, Third Edition. SLACK Inc. 2004). However, the lens can also be removed even if it is not opacified and replaced by an IOL. In this case the extraction seeks a refractive end: the elimination of a refractive error (myopia, farsightedness and / or astigmatism). To this end, the lens can also be maintained, an IOL inserted into the anterior / posterior chamber of the eye and thus eliminate the refractive error (phakic IOL, Alió JL and Pérez-Santonja JJ in Refractive Surgery with Phakic IOLs, SLACK Inc. 2004) .

[8] Most of the IOLs developed so far do not provide an optical design that provides the best optical quality of the lens plus eye set and consequently the best image quality formed on the retina. The patients to whom these IOLs apply refer to decreased vision quality (Montés-Micó et al. In J Cataract Refract Surg 2003, -29: 703-11 and Ophthalmology 2004; lll; 85-96) mainly due to presence of a certain amount of optical aberrations.

[9] Depending on the polychromatic nature or not of light, there are two types of aberrations: chromatic and monochromatic. The chromatic dispersion in the eye causes the presence of chromatic aberrations (longitudinal and transverse) that considerably diminish the vision of the details (Thibos et al, in Optom Vis Sci 1991; 68: 599-607). But even, in the event that the eye did not scatter the light, there are other types of aberrations (monochromatic aberrations) that also affect the vision of the details. Due to their presence in the human eye, low-order aberrations (blur and astigmatism) and spherical aberration (Castejón-Mochón et al in Vis Res 2002; 42: 1611-7) are of particular relevance. In polychromatic light both types of aberrations (chromatic and monochromatic) are present in the eye depending on each other. Specifically, the variation of the spherical aberration with the wavelength causes the so-called spherochromatic aberration, which can considerably affect the optical quality of the image formed in the retina and inexorably the quality of vision. Therefore, for an IOL to provide good optical quality in the eye, it must correct both chromatic aberrations and monochromatic aberrations.

[10]

Description of the Invention

[11] The objective of the invention is to develop a new IOL to be implanted in the human eye. In the design of the new IOL, the presence in the eye of monochromatic spherical aberration and chromatic aberration has been considered. The implementation of the proposed IOL is intended to reduce these aberrations and provide better optical quality and consequently greater visual performance of the human eye.

[12] In view of the above, there is a need to develop an IOL that is better suited to aberrations, both monochromatic and chromatic, present in the human eye and that provides the best optical quality. The IOL developed in this invention solves problems not considered in previous patents that do not take into account both aberrations nor, therefore, spherochromatic aberration. Such a design improves the optical quality of previous IOLs, being able to reduce monochromatic spherical aberration, chromatic aberration and spherochromatic aberration so that together it provides better optical quality, better quality in the retinal image and therefore of visual quality

[13] The design of the new IOL is based on a hybrid lens with two surfaces, being a refractive surface and the other diffractive, that is, with different optical properties. The combination of both surfaces in the same lens compensates for the chromatic dispersion of the human eye. On the other hand, at least one of the surfaces is aspheric, which makes it possible to reduce the spherical aberration of the entire eye once the IOL is inserted. The compensation of both aberrations also decreases the spherochromatic aberration and can increase the depth of focus of the eye allowing better vision at different distances.

[14] A first aspect of the invention relates to an IOL (intraocular lens) configured to be implanted in a human eye comprising a first surface and a second surface with different optical properties, where

[15] one of said surfaces is diffractive;

[16] one of said surfaces is refractive;

[17] at least one of said surfaces is aspheric;

[18] said first surface and said second surface defining a structure that has a plurality of optical properties that take into account: [19] chromatic dispersions of the ocular media,

[20] spherical monochromatic aberrations of the comea and lens and

[21] spherochromatic aberrations due to the change of spherical monochromatic aberrations with light scattering; [22] to reduce spherical monochromatic aberrations, chromatic aberrations and spherochromatic aberrations. [23] According to this first aspect, different variants of the invention are defined: [24] - IOL where the first surface is spherical refractive and the second surface is aspherical diffractive. [25] - IOL where the first surface is aspherical diffractive and the second surface is spherical refractive. [26] - IOL where the first surface is aspherical refractive and the second surface is spherical diffractive. [27] - IOL where the first surface is spherical diffractive and the second surface is aspherical refractive. [28] - IOL where the first surface is aspherical refractive and the second surface is aspherical diffractive. [29] - IOL where the first surface is aspherical diffractive and the second surface is aspherical refractive. [30] - IOL where the first surface is spherical refractive and the second flat diffractive surface. [31] - IOL where the first surface is flat diffractive and the second surface is spherical refractive. [32] - IOL where the first surface is flat diffractive and the second surface is aspherical refractive. [33] - IOL where the first surface is aspherical refractive and the second surface is flat diffractive. [34] The IOL of the invention is configured to be placed in a position in the human eye selected from: a posterior chamber, an anterior chamber, a capsule, a cornea and a vitreous. [35] Also, the IOL is configured to be placed in a human eye with or without a lens. [36] On the other hand, the IOL is composed of a soft or hard material that presents biocompatibility with the human eye. The IOL material may be selected from: acrylic, silicone, hydrogel, methyl methacrylate and combinations thereof. [37] Additionally, the IOL also includes haptics to be implanted in the human eye, said haptics being configured to place the IOL in a position in the human eye selected from: a posterior chamber, an anterior chamber, a capsule, a coma and a vitreous. [38] The IOL may also comprise a material with selective transmittance at certain wavelengths. [39] Similarly, the IOL is configured to allow movement and pseudo-accommodation of said lens. [40] Optionally, the first and / or second surfaces of the IOL have radial variations in curvature so that the lens has different foci to obtain a

Multifocal IOL [41]

BRIEF DESCRIPTION OF THE DRAWINGS [42] A series of drawings that help to better understand the invention and that expressly relate to an embodiment of said invention that is presented as a non-limiting example thereof is described very briefly below. . [43] Figure 1 shows some of the different IOL designs in their possible combinations with convex curvatures.

[44] Figure 2 shows the polychromatic Modulation transfer (MTF) function for the example eye model, with the IOL proposed in the example

(solid line), the reference IOL of the example (dotted line); and limited diffraction system (gray line). [45] Figure 3 shows the focus offset (D, diopters) for different wavelengths for the example eye model, with the IOL proposed in the example (solid line), and the reference IOL (dotted line ) proposal in example. [46] Figure 4 shows the optical path difference (Optical Path Difference, OPD) in axis at the entrance pupil for the five wavelengths used (see figure) in the example eye model, with the proposed IOL ( a), and the reference IOL (b). [47]

Description of a preferred embodiment of the invention [48] The proposed lens is a combination of a refractive and a diffractive surface presented below:

[49] S 1: Standard spherical refractive surface determined by its sudden (z):

[50] z = cr ² / [1 + (1- (1 + k) cV) ^1/2 ]

[51] where: c is the curvature and can be its positive, negative or null value (flat surface), r is the radial coordinate in lens units and k is the conical constant. [52] S2: Uniform-smooth aspherical refractive surface, determined by its sudden (z):

[53] z = cr ² / [1 + (1- (1 + k) cV) ^1/2 ] + α _i r ² [54] where: c is the curvature and can be its positive, negative or null value (flat surface), r is the radial coordinate in lens units, k is the conical constant and α is a constant. [55] S3: Spherical diffractive surface similar to the surface Sl with a phase variation (Φ) of the type: [56] O = P ₁ V ₊ P ₂ V

[57] where: P and P are constants and r is the corresponding normalized radial opening coordinate. [58] S4: Aspheric diffractive surface similar to surface S2 with a phase variation (Φ) of the type: [59] O = P ₁ V ₊ P ₂ V

[60] where: P and P are constants and p is the corresponding normalized radial opening coordinate. [61] S5: Flat diffractive surface with a phase variation (Φ) of the type:

[62] O = P ₁ V ₊ P ₂ V

[63] where: P and P are constants and p is the corresponding normalized radial opening coordinate. [64] The combinations of surfaces to form the IOL (in each case including two surfaces with different optical properties are the following: [65]

1. Refractive surface Sl ₊ Diffractive surface S4

2. S4 diffractive surface + S 1 refractive surface

3. S2 refractive surface + S3 diffractive surface

4. S3 diffractive surface + S2 refractive surface

5. Refractive surface S2 + Diffractive surface S4

6. S4 diffractive surface + S2 refractive surface

7. Refractive surface Sl ₊ D5 diffractive surface

8. S5 diffractive surface + Sl refractive surface

9. S5 diffractive surface + S2 refractive surface

10. S2 refractive surface + S5 diffractive surface

[66] In addition to the described optical structure, the new IOL can be designed with a material that includes a chromophore capable of selectively reducing the transmittance of certain wavelengths.

[67] The main application of the proposed IOL is the improvement of optical and visual quality [Visual Acuity, Monochromatic and Polychromatic Modulation Transfer Function (MTF, hereinafter), Contrast Sensitivity Function, ...] person who has been implanted.

[68] An example of IOL that compensates for spherical aberration is described below. and chromatic of an eye model.

[69] The proposed eye model is composed of four surfaces (two for the cornea and two for the IOL), a flat iris and a spherical retina. The specific data are indicated in table 1.

[70]

[71] Table 1 [72] The α, and β parameters have been optimized to minimize the mean square value (Root Mean Square or RMS) measured in the pupil plane, but can also be optimized to minimize another type of quality parameter of image both in the pupil plane and in the retina plane.

[73] In addition to the values in Table 1, the following general values of the optical system have been used:

[74] - Entrance pupil = 5 mm in diameter [75] - Wavelengths: 470, 510, 555, 610 and 650 nm. [76] - To simulate the different spectral sensitivity of the eye, the following weights have been given to the corresponding wavelengths: 0.091 (470 nm); 0.503 (510 nm); 1 (555 nm); 0.503 (610 nm) and 0.107 (650 nm).

[77] - The variation of refractive indices with wavelength is given by the following expression:

[78] n = n + A / λ + B / λ 3.5 [79] where the specific values of n, A and B used in the model come from table 2.

[81] Table 2 [82] These data are also approximate and may vary depending on the measurements taken.

[83] The material of the IOL is PMMA (PolyMetilMetAcrylate), but it could be another for example: a soft or hard material that has biocompatibility with the human eye selected from: acrylic, silicone, hydrogel, methyl methacrylate.

[84] In order to compare the results with a conventional IOL manufactured with PMMA, the values of an IOL (reference IOL) have been used with the optimal spherical surfaces that minimize the variance of the wave aberration (RMS). In our example, these surfaces have taken the radii of curvature of 10.489273 mm and -44.134751 mm for the first and second surfaces respectively.

[85] Figure 2 shows the values of polychromatic MTF on the horizontal axis of the eye model with the proposed IOL (solid line); the reference IOL (dotted line) and the one corresponding to the diffraction limited system (gray line).

[86] Figure 3 shows the focus offset (D) for different wavelengths (longitudinal chromatic aberration) with the proposed IOL (solid line), and the reference IOL (dotted line).

[87] Figure 4 shows the optical path difference (OPD) in wavelengths (1 wavelength = 0.555 microns), in axis at the entrance pupil for the five wavelengths used (indicated within the figure itself ) for the proposed IOL (a), and the reference IOL (b).

[88] Figures 2, 3 and 4 show the significant reduction of both monochromatic and chromatic aberrations of the proposed eye model when the proposed IOL is implanted in comparison to a conventional spherical surface IOL.

[89] The eye model values presented (Table 1 and 2), are approximate values that may change depending on the specific eye model used. The change of these values would vary the values of α and β (and that of β in case a diffractive and aspherical surface type S4 is used) obtained and presented in table 1. More wavelengths and other wavelengths can also be taken pupillary radius that also They would dictate these values.

Claims

The Claims

[I] An IOL (infraocular lens) configured to be implanted in a human eye comprising a first surface (1) and a second surface (2) with different optical properties, characterized in that:

- one of said surfaces is diffractive;

- one of said surfaces is refractive;

- at least one of said surfaces is aspherical; said first surface (1) and said second surface (2) defining a structure that has a plurality of optical properties that take into account:

- chromatic dispersions of the ocular media,

- spherical monochromatic corneal and crystalline aberrations and

- spherochromatic aberrations due to the change of spherical monochromatic aberrations with the scattering of light; to reduce spherical monochromatic aberrations, chromatic aberrations and spherochromatic aberrations and increase the depth of focus of the eye. [2] The IOL of claim 1 characterized in that the first surface (1) is spherical refractive (Sl) and the second surface (2) is aspherical diffractive (S4). [3] The IOL of claim 1 characterized in that the first surface (1) is aspherical diffractive (S4) and the second surface (2) is spherical refractive (Sl). [4] The IOL of claim 1 characterized in that the first surface (1) is aspherical refractive (S2) and the second surface (2) is spherical diffractive (S3). [5] The IOL of claim 1 characterized in that the first surface (1) is spherical diffractive (S3) and the second surface (2) is aspherical refractive (S2). [6] The IOL of claim 1 characterized in that the first surface (1) is aspherical refractive (S2) and the second surface (2) is aspherical diffractive (S4). [7] The IOL of claim 1 characterized in that where the first surface

(1) is aspherical diffractive (S4) and the second surface (2) is aspherical refractive

(S2). [8] The IOL of claim 1 characterized in that the first surface (1) is spherical refractive (Sl) and the second surface (2) is flat diffractive (S5). [9] The IOL of claim 1 characterized in that the first surface (1) is flat diffractive (S5) and the second surface (2) is spherical refractive (Sl). [10] The IOL of claim 1 characterized in that the first surface (1) is flat diffractive (S5) and the second surface (2) is aspherical refractive (S2).

[II] The IOL of claim 1 characterized in that the first surface (1) is aspherical refractive (S2) and the second surface (2) is flat diffractive (S5).

[12] The IOL of claims 1-11 characterized in that it is configured to be placed in a position in the human eye selected from: a posterior chamber, an anterior chamber, a capsule, a cornea and a vitreous.

[13] The IOL of claims 1-12 characterized in that it is configured to be placed in a human eye with or without a lens.

[14] The IOL of claims 1-13 characterized in that it is composed of a material that exhibits biocompatibility with the human eye.

[15] The IOL of claims 1-14 characterized in that it further comprises haptics to be implanted in the human eye, said haptics being configured to place the IOL in a position in the human eye selected from: a posterior chamber, an anterior chamber , a capsule, a cornea and a vitreous.

[16] The IOL of claims 1-15 characterized in that it further comprises a material with selective transmittance at certain wavelengths.

[17] The IOL of claims 1-16 characterized in that it is configured to allow movement and pseudo-accommodation of said lens.

[18] The IOL of claims 1-17 characterized in that the first and / or second surfaces have radial variations in curvature so that the lens has different foci to obtain a multifocal IOL.