WO2006025726A1

WO2006025726A1 - Artificial intraocular lens

Info

Publication number: WO2006025726A1
Application number: PCT/NL2004/000613
Authority: WO
Inventors: Gerrit Ludolph Van Der Heijde
Original assignee: Vu Medisch Centrum
Priority date: 2004-09-02
Filing date: 2004-09-02
Publication date: 2006-03-09

Abstract

Artificial intraocular lens, comprising two lens elements (1, 2), arranged one behind the other along the optical axis (Z) of the lens (L), wherein at least one of the lens elements (1, 2) is movable relative to the other transversely to the optical axis (Z) of the lens (L), wherein the optical thicknesses of the lens elements (1, 2) are such, that the power of the lens changes by transversal displacement of at least one of the lens elements (1, 2) relative to the other. In an embodiment, the intraocular lens is a an Alvarez-type lens.

Description

Title: Artificial intraocular lens

The invention relates to a new type of artificial intraocular lens.

Various artificial intraocular lenses are known from the prior art. The artificial lens is usually implanted in the eye of a patient by surgery, and usually serves as a replacement of the natural lens of the patient. This may be desired, for example, when the natural lens does not function properly, when the natural lens is spoilt, degraded, clouded and/or otherwise negatively affected.

Commonly known are artificial intraocular lenses which consist of suitable lens bodies, see for instance US 6,638,306B2 which describes an accommodating intraocular lens having a lens body as well as several haptics for holding the lens in the eye.

A problem of known, proposed intraocular lenses, and particularly of proposed accommodatable artificial lenses, is, that a desired large power variation of accommodating artificial lenses is relatively hard to achieve. Until the present day, many different solutions have been proposed for providing a properly functioning intraocular lens, however, none of these solutions has been found sufficiently satisfying.

The present invention aims to alleviate at least some of the above- mentioned problems. An object of the invention is to provide an improved intraocular lens.

Also an object of the invention is, to provide an artificial intraocular lens, which can provide relatively good vision and/or large power variations.

Also, an object of the invention is to provide a properly accommodating intraocular lens. According to an aspect of the invention, there is provided an artificial intraocular lens, comprising two lens elements, arranged one behind the other along the optical axis of the lens, wherein at least one of the lens elements is movable relative to the other in transversely to the optical axis of the lens, wherein the optical thicknesses of the lens elements are such, that the power of the lens changes by transversal displacement of at least one of the lens elements relative to the other.

According to a further aspect of the invention, the lens is arranged substantially according to the variable power lens of American patent US 3,305,294.

In that case, the commonly known Alvarez-type lens is applied as an interocular lens. By using the Alvarez lens as intraocular lens, relatively large power variations can be achieved in a surprisingly simple manner. The patent US 3,305,294 is considered to be entirely incorporated in the present patent application by reference, particularly for explanation of the commonly known basic principles of the Alvarez lens, but also for providing one or more possibilities of constructing and arranging such an Alvarez lens. Therefore, the description, claims and drawings of US 3,305,294 are considered tαbe part of the present patent application. It is to be noted, that the main concept of the Alvarez lens may extend beyond the basic principles that are laid down in US 3,305,294.

The use of the Alvarez-type lens extraocularly as such , in spectacles, is known, as was proposed by Alvarez 40 years ago in US 3,305,294. Until the present invention, no one came to the innovative idea that such a Alvarez lens, which comprises lens elements that are movable relative to the other transversely to the optical axis of the lens, is advantageous to be used as an intraocular lens.

In an embodiment of the invention, optical thicknesses of the two lens elements correspond substantially to those of the elements of the variable power lens of Luis W. Alvarez of the American patent US 3,305,294.

In an aspect of the invention, the optical thickness t of each of said lens elements can be substantially defined by the following formula: t=A(xy²+l/3x³)+Bx²+Cxy+ Dx+E +F(y) wherein B, C, D and E are constants that may be given any practical value, including zero, and F(y) is a function that is independent of x and may be zero, x and y represent coordinates on a rectangular coordinate system centered on the optical axis and lying in a plane perpendicular thereto, and A is a constant representing the rate of lens power variation with lens movement in the x direction. This formula is explained in US 3,305,294.

In an embodiment of the invention, the lens comprises means for moving at least one of the lens elements relative to the other in a direction transverse to the optical axis of the lens. Furthermore, according to the invention, the lens can be an accommodating intraocular lens, to be actuated by the ciliary muscle of an eye of an user.

In a further aspect of the invention, the said means for moving the at least one of the lens elements relative to the other comprise haptics which are arranged to couple said lens elements directly and/or indirectly to the ciliary muscle.

In an embodiment, each of said lens elements has polished surfaces with one of the surfaces being a regular surface of revolution.

In an embodiment of the invention, the two lens elements are disposed in closely spaced alignment along the optical axis.

Also, according to an aspect of the invention, the angles of the lens surfaces with respect to a plane normal to the optical axis are such, that total reflection is avoided during use.

In an aspect of the invention, the optical thickness t of each of said lens elements follows from the solution of the following triad of differential equations:

5³t/5xδy²=2A, and δ³t/5x²5y=0. These differential equations, which are also described in US 3,305,294, provide an alternate criteria for novel lens elements to be used in an intraocular lens.

Besides, the present invention provides an use of an intraocular lens, wherein the lens is implanted in a human eye, wherein preferably the lens accommodates by movement of at least one of the lens elements with respect to the other.

In an aspect of the invention, a method for manufacturing an artificial intraocular lens is characterised in that an Alvarez-type lens is manufactured such, that the lens is implantable in an eye, for instance in a human eye.

In an other aspect of the invention, there is provided a method for implanting the new artificial intraocular lens into an eye, wherein the lens is being positioned with its optical axis extending on the optical axis of the eye, wherein said two lens elements are coupled such to the eye, for instance using haptics, that at least one of the lens elements is transversally moveable relative to the optical axis of the lens.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: fig. 1 a schematic cross-section of a first embodiment of the invention, wherein the lens elements are in a zero-power position; fig. 2 a similar cross-section as fig. 1 wherein the lens elements are in a negative-power position fig. 3 a similar cross-section as fig. 1 wherein the lens elements are in a positive -power position; fig. 4 a schematic cross-section of a second embodiment of the invention during use, wherein the lens elements are in a first transversal position; and fig. 5 a similar cross-section as fig. 4 wherein the lens elements are in a second transversal position.

Figures 1-3 schematically show a first embodiment of the present invention, in cross-section. The embodiment is an artificial intraocular Alvarez-type lens L.

The intraocular lens L comprises two lens elements 1, 2, arranged in an optical tandem relation, one behind the other along the optical axis Z of the lens L. In the present embodiment, both of the lens elements 1, 2 are movable relative to the other in a direction transverse to the optical axis Z of the lens L. Alternatively, only one of the lens elements can be movable with respect to said optical axis. Z. The elements 1, 2 may be made of a suitable optics material, for instance optical glass, transparent plastic and/or any other suitable material.

The optical thicknesses of the lens elements 1, 2 are such, that the power of the overall lens L changes by transversal displacement of at least one of the lens elements 1, 2 relative to the other. Particularly, in the present embodiment, the optics of the overall lens L is arranged substantially according to the optics of the Alvarex-lens of American patent US 3,305,294. Optical thicknesses of the two lens elements 1, 2 correspond substantially to those of the elements of the variable power lens of Luis W. Alvarez, as described in the American patent US 3,305,294.

In the present embodiment, the optical thickness t of each lens element 1, 2 follows from the solution of the following triad of differential equations:

d³t/dxdy²=2A, and

8H/dx²dy=0, wherein A is a constant, and x and y are coordinates along the x-axis and y-axis. For instance, said optical thickness is substantially defined by the following formula: t=A(xy²+l/3x³)+Bx²+Cxy+ Dx+E +F(y) wherein B, C, D and E are constants that may be given any practical value, including zero, and F(y) is a function that is independent of x and may be zero, x and y represent coordinates on a rectangular coordinate system centered on the optical axis and lying in a plane perpendicular thereto, and A is a constant representing the rate of lens power variation with lens movement in the x direction. This formula is already explained in US 3,305,294. When each of the two lens elements substantially complies to this formula, aberration of the lens can be substantially reduced. Besides, in this manner, the lens elements can be made relatively thin.

The lens L comprises means for moving at least one, or both, of the lens elements 1, 2 relative to the other in said transverse direction. Preferably, the lens elements 1, 2 are moved by equal amounts in opposite directions during use. The means for moving the lens element(s) are not visible in figures 1-3. Preferably, the lens L is to be used as an accommodating intraocular lens, to be actuated by the ciliary muscle of an eye of an user after implantation. In that case, said means for moving the at least one of the lens elements 1, 2 relative to the other can be provided by a suitable number of haptics which are arranged to couple said lens elements 1, 2 directly or indirectly to the ciliary muscle in a manner, suitable for moving that at least one lens element 1, 2. To that aim, for example, rigid and/or flexible haptics may be applied. Such haptics are commonly known to the skilled person. Furthermore, each of said lens elements 1, 2 preferably has polished surfaces with one of the surfaces being a regular surface of revolution. Also, in the present embodiment, the two lens elements 1, 2 are disposed in closely spaced alignment along the optical axis Z, as is clearly visible in figures 1-3. Each element has at least one surface of varying curvature with all lens surfaces having all portions thereof inclined at angles less than sixty degrees to a plane perpendicular to said optical axis, to avoid total reflections. Said regular surface of revolution and surface of varying curvature as such are already explained in detail in said US 3,305,294.

Figure 1 shows a neutral or zero-power transverse position of the two elements 1, 2. In this first position, the total optical thickness of the intraocular lens L is constant. Therefore, in the present embodiment, the lens L will not change the direction of propagation incoming light with respect to the optical axis Z, apart from a very small negligible transveral shift. The propagation of light rays is schematically depicted by arrows R in figures 1-3. In figure 2, the lens elements 1, 2 of the intraocular lens L have been shifted transversely with respect to the optical axis Z to form a negative power lens. In figure 3, the elements 1, 2 have been moved in a reverse direction to form a positive power intraocular lens L. Thus, clearly, the intraocular lens L has a variable focus. The amount of change of focus with respect to the amount of movement of the lens elements 1, 2 is directly related to the abovementioned term A in said formula of Alvarez. The amount of power variation that can be achieved with the embodiment shown can be relatively large.

When the lens L has been implanted in the eye, it can accommodate during use. This has been depicted schematically in figures 4 and 5, showing an implanted second embodiment of the invention.

The second embodiment is an intraocular lens L', comprising a first lens element l'and second lens element 2' forming an Alvarex-type lens. The optical axis of the second embodiment, which axis is depicted in figures 4 and 5 by broken line Z', extends substantially on the optical axis of the eye. The lens elements 1', 2' of the second embodiment are coupled indirectly to the ciliary muscle CM of the eye, by haptics 8, 9, the capsular bag CB and zonules ZN. The haptics 8, 9 connect the lens elements 1', 2¹ to the capsular bag CB, whereas the capsular bag CB is secured to the ciliary muscle CM by the zonules ZN. The haptics 8, 9 are arranged such that the lens elements 1', 2' are transversally moveable relative to said optical axis Z' during use, during contraction and relaxation of the ciliary muscle CM.

In figure 4, the ciliary muscle CM is in a relaxed state. In that case, the two lens elements I¹, 2' have been moved to a first transverse position, such that the lens L' formed by these elements I¹, 2' has a certain positive optical power. In this case, the lens L' may provide, for instance, in-focus distant vision, with relatively little aberrations.

In figure 5, the ciliary musle CM is in a contracted state. Due to the contraction of the ciliary muscle CM, the lens elements 1', 2' have been moved to a second transverse position. In this second position, the positive optical power of the artificial lens L' has increased. Then, the lens L' may provide for near vision, also with relatively little aberrations.

Preferable, before the lens L' is being implanted in the eye, lens elements 1', 2' can be chosen to provide a suitable optical arrangement and/or shape, such, that the resulting implanted artificial lens L' provides a suitable power variation for allowing a specific user to have both in-focus near vision and in-focus far vision. Also, clearly, the two lens elements I¹, 2' can simply be positioned in appropriate transversal positions in the eye, for instance during the implantation of the lens L¹, for providing sharp in focus vision. The descriptions above are intended to be illustrative, not limiting.

Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

For instance, the new intraocular lens as provided by the present invention may by an Alvarez-type lens, as has been explained in the above, but the lens can also be of different construction while the lens still comprises at least the following features: two lens elements, arranged one behind the other along the optical axis of the lens, wherein at least one of the lens elements is movable relative to the other in a direction transverse to the optical axis of the lens, wherein the optical thicknesses of the lens elements are such, that the power of the lens changes by transversal displacement of at least one of the lens elements relative to the other.

The term "lens", where the context allows, may refer to any one or combination of various types of optical components, as long as optical thicknesses of the components can be such, that the power of the lens changes by transversal displacement of at least one of the optical components relative to the other.

The artificial lens can be manufactured in various ways using various materials, as will be clear to the skilled person. The lens combination may have a wide variety of shapes including planar, elliptical, cylindrical, and spherical. Thus one surface of the lens element can for example be a regular surface of revolution, a planar, elliptical, cylindrical, spherical surface or the like surface.

Claims

1. Artificial intraocular lens, comprising two lens elements (1, 2), arranged one behind the other along the optical axis (Z) of the lens (L), wherein at least one of the lens elements (1, 2) is movable relative to the other transversely to the optical axis (Z) of the lens (L), wherein the optical thicknesses of the lens elements (1, 2) are such, that the power of the lens changes by transversal displacement of at least one of the lens elements (1, 2) relative to the other .

2. An artificial intraocular lens according to claim 1, wherein the lens is arranged substantially according to the variable power lens of American patent US 3,305,294.

3. An artificial intraocular lens according to claim 1 or 2, wherein optical thicknesses of the two lens elements correspond substantially to those of the elements of the variable power lens of Luis W. Alvarez of the American patent US 3,305,294.

4. An artificial intraocular lens according to any of the preceding claims, wherein the optical thickness t of each of said lens elements (1, 2) is substantially defined by the following formula: t=A(xy²+l/3x³)+Bx²+Cxy+ Dx+E +F(y). wherein B, C, D and E are constants that may be given any practical value, including zero, and F(y) is a function that is independent of x and may be zero, x and y represent coordinates on a rectangular coordinate system centered on the optical axis and lying in a plane perpendicular thereto, and A is a constant representing the rate of lens power variation with lens movement in the x direction.

5. An artificial intraocular lens according to any of the previous claims, comprising means for moving at least one of the lens elements (1, 2) relative to the other in a direction transverse to the optical axis of the lens.

6. An artificial intraocular lens according to any of the preceding claims, wherein the lens is an accommodating intraocular lens, to be actuated by a ciliary muscle of an eye of an user.

7. An artificial intraocular lens according to claims 5 and 6, wherein said means for moving at least one of the lens elements (1, 2) relative to the other comprise haptics which are arranged to couple said lens elements (1, 2) directly and/or indirectly to a ciliary muscle.

8. An artificial intraocular lens according to any of the preceding claims, wherein each of said lens elements (1, 2) has polished surfaces with one of the surfaces being a regular surface of revolution.

9. An artificial intraocular lens according to any of the preceding claims, wherein the two lens elements (1, 2) are disposed in closely spaced alignment along the optical axis (Z) of the lens (L).

10. An artificial intraocular lens according to any of the preceding claims, wherein the angles of the lens surfaces with respect to a plane normal to the optical axis are such, that total reflection is avoided during use..

11. An artificial intraocular lens according to any of the preceding claims, wherein the lens is an Alvarez-type lens.

12. An artificial intraocular lens according to any of the preceding claims, wherein the optical thickness t of each of said lens elements follows from the solution of the following triad of differential equations:

δ³t/dxdy²=2A, and d³t/dx²dy=0.

13. Use of an intraocular lens according to any of the preceding claims, wherein the lens is implanted in a human eye, wherein preferably the lens accommodates by movement of at least one of the lens elements (1, 2) with respect to the other.

14. Method for manufacturing an artificial intraocular lens, wherein an Alvarez-type lens is manufactured such, that the lens is implantable in an eye, for instance in a human eye.

15. Method for implanting a lens according to any of claims 1-12 into an eye, wherein the lens (L) is being positioned with its optical axis (Z) extending on the optical axis of the eye, wherein said two lens elements (1, 2) are coupled such to the eye, for instance using haptics, that at least one of the lens elements (1, 2) is transversally moveable relative to the optical axis (Z) of the lens (L).

16. Method according to claim 15, wherein the lens (L) is being coupled directly and/or indirectly to the ciliary muscle (CM) of the eye, to be actuated thereby after implantation of the lens (L).