NL2012133B1 - Intraocular lens with free-form optical surfaces. - Google Patents

Abstract

The invention relates to an intraocular artificial lens of variable optical power, comprising at least two optical elements of which at least one element is shiftable in a direction perpendicular to the optical axis with each of the optical elements having at least one free-form optical surface with such a shape that the combination of free-form surfaces exhibits different optical powers at different relative positions of the optical elements characterized in that the free-form surfaces have such a shape that said combination of surfaces is adapted to provide a non-linear change in optical power with linear shift of the optical elements in a direction perpendicular to the optical axis.

Description

Intraocular lens with free-form optical surfaces

The invention concerns an intra ocular lens. Such a lens is generally known. Artificial intra ocular lenses are used inter alia to treat cataracts to replace the opaque cataracterous natural lens of the eye. These intra ocular lenses have a fixed optical power. The optical power of the intra ocular lens can become sub-optimal due to changes in the optical characteristics of the eye, for example changes due to aging. The optical power has to be corrected by either spectacles or surgical replacement of the intra ocular lens by a new intra ocular lens.

Also, due to the fixed optical power the natural accommodation function of the eye will be lost. As a consequence the person in which the intra ocular lens is implanted will have to rely on spectacles to aid accommodation. US-A-4 994 082 discloses an artificial intra ocular lens of variable optical power comprising at least two optical elements which can be shifted relative to each other in a direction extending perpendicular to the optical axis wherein the optical elements have such a shape that they exhibit, in combination, different optical powers at different relative positions. The lenses employed in this prior art design will in combination not function as a variable lens suitable for projecting an image on the retina.

The aim of the present invention is to provide a variable lens of the kind referred to above, which is adapted to project a proper image on the retina and is adapted to provide accommodative power for focusing.

This aim is reached in prior art documents such as for example US2012323321, US2012323320, US2009024214 in that the accommodative power for focussing is provided by at least one optical element with an optical thickness according to the formula t = A (xy2 +1/3 x3) + Bx2 + Cxy + Dx + E + F(y), wherein t is the lens thickness of the optical element in the direction of the optical axis, and x is the coordinate in the direction of the motion of the optical elements, y is the coordinate in the direction perpendicular to the optical axis and to the x-direction and A is a constant. Such variable lens is suitable to project a proper image on the retina and to provide said accommodative power for focusing.

We refer to US-A-3 305 294 from which the principle of variable optical power of such a lens is known, albeit in inter alia spectacles, the formula for the optical thickness t being derived in the document in detail. Also US-A-3 583790 is noted which further describes the optics..

The present document discloses an intraocular artificial lens of variable optical power, comprising at least two optical elements of which at least one element is shiftable in a direction perpendicular to the optical axis with each of the optical elements having at least one free-form optical surface with such a shape that the combination of free-form surfaces exhibits different optical powers at different relative positions of the optical elements with the free-form surfaces having such a shape that said combination of surfaces is adapted to provide a non-linear change in optical power with linear shift of the optical elements in a direction perpendicular to the optical axis.

Combinations of surfaces is adapted to provide a linear change in optical power with linear shift of the optical elements in a direction perpendicular to the optical axis are known from prior art documents, for example US2012323321, US2012323320, US2009024214 all which documents are incorporated in the present document by reference and various other prior art publications. All these lenses comprise free-form surfaces according to formulas which formulas include at least one term to the third order providing cubic surfaces or variations thereon.

The present invention is an intraocular lens with a combination of free-form surfaces with shapes according to at least one formula which describes said free-form surfaces contain at least one term of the fourth or higher order. So, the combination of free-form surfaces can provide a variable parabolic lens.

Furthermore, the intraocular lens can comprise driving means including a mainly rigid connecting element connected at its first side to an optical element for driving at least one of the optical elements for executing a movement relatively to the other optical element, and positioning means for positioning the optical elements in the eye, including a flexible connecting component which is at its first side connected to the optical element at one end of said optical element opposite the rigid connecting component, with the optical elements adapted to be move in tandem with the ciliary muscle of the eye, and can also comprise at least one Ω-shaped structure is included in each of the flexible connecting components and that the optical elements form a lens with the weakest optical dioptre power in their most overlapping position and a lens with the strongest optical dioptre power in their least overlapping position or that the optical elements form a lens with the strongest optical dioptre power in their most overlapping position and a lens with the weakest optical dioptre power in their least overlapping position and the Ω-shaped structures can comprise stopping shoulders, with the intraocular artificial lens comprising positioning means are adapted to urge the optical elements to a resting position when the driving means are inactive and that the optical elements at the resting position exhibit an optical power related to nearby or to distance vision and the side of the rigid and flexible connecting elements respectively can be situated opposite the side which is connected to the optical element is fitted with anchors adapted to move in tandem with the ciliary muscle with, additionally, the positioning means adapted to adjust the resting position of the optical elements after implantation, with positioning means which can include an element of which a size is adjustable and with the lens is adapted to provide a combination of fixed refractive correction and accommodation to the aphakic eye in which the lens is subsequently implanted.

Examples of quadric surfaces include the cone, cylinder, ellipsoid, elliptic cone, elliptic cylinder, elliptic hyperboloid, elliptic paraboloid, hyperbolic cylinder, hyperbolic paraboloid, paraboloid, sphere, and spheroid. Quintic surfaces are an option to reach comparable results, but herewith complexity increases Examples of quadric surfaces are:

So, the present document discloses an intraocular artificial lens of variable optical power, comprising at least two optical elements of which at least one element is shiftable in a direction perpendicular to the optical axis with each of the optical elements having at least one free-form optical surface with such a shape that the combination of free-form surfaces exhibits different optical powers at different relative positions of the optical elements such that the free-form surfaces have such a shape that said combination of surfaces is adapted to provide a non-linear change in optical power with linear shift of the optical elements in a direction perpendicular to the optical axis, which surfaces can be quadric or quintic surfaces or the formulas which describe said free-form surfaces can contain at least one term of the fourth order, or the formulas which describe said free-form surfaces contain at least one term of any order exceeding the fourth order, or the free-form surfaces are a combination of any surface mentioned above, and the combination of free-form surfaces can be adapted to provide a variable parabolic lens, which lens, or any other lens mentioned above, can comprise driving means which can include a mainly rigid connecting element connected at its first side to an optical element for driving at least one of the optical elements for executing a movement relatively to the other optical element, and positioning means for positioning the optical elements in the eye, including a flexible connecting component which is at its first side connected to the optical element at one end of said optical element opposite the rigid connecting component, with the optical elements adapted to be move in tandem with the ciliary muscle of the eye, with a Ω-shaped structure which can be included in each of the flexible connecting components and that the optical elements form a lens with the weakest optical dioptre power in their most overlapping position and a lens with the strongest optical dioptre power in their least overlapping position or that the optical elements form a lens with the strongest optical dioptre power in their most overlapping position and a lens with the weakest optical dioptre power in their least overlapping position and the Ω-shaped structures can comprise stopping shoulders, and with the positioning means are adapted to urge the optical elements to a resting position when the driving means are inactive and that the optical elements at the resting position exhibit an optical power related to nearby or to distance vision, with the side of the rigid and flexible connecting elements respectively which can be situated opposite the side which is connected to the optical element is fitted with anchors adapted to move in tandem with the ciliary muscle with positioning means which can be adapted to adjust the resting position of the optical elements after implantation, with the positioning means which can include an element of which a size is adjustable, with the lens such that it can be adapted to provide a combination of fixed refractive correction and accommodation to the aphakic eye in which the lens is subsequently implanted, in the capsular bag of the eye, or, in the sulcus of the eye, or in the iris of the eye.

Claims (19)

An intraocular artificial lens of variable optical power, comprising at least two optical elements, at least one of which is slidable in a direction perpendicular to the optical axis, each of the optical elements having at least one free surface optical surface of: a shape such that the combination of free-form surfaces exhibits different optical powers at different relative positions of the optical elements, characterized in that the free-form surfaces have a shape such that the combination of surfaces is arranged to form a provide a linear change in optical power with a linear shift of the optical elements in a direction perpendicular to the optical axis. An intraocular artificial lens according to claim 1, characterized in that the free-form surfaces are quadratic surfaces. An intraocular artificial lens according to claim 1, characterized in that the free-form surfaces are quintical surfaces. An intraocular artificial lens according to claim 1, characterized in that the formulas describing the free-form surfaces comprise at least one fourth-order term. The intraocular artificial lens according to claim 1, characterized in that the formulas describing the free-form surfaces comprise at least one term of each order greater than the fourth order. The intraocular artificial lens according to claim 1, characterized in that the free-form surfaces are a combination of any surface of any order according to claims 1 to 5. An intraocular artificial lens according to any one of the preceding claims, characterized in that the combination of free-form surfaces is arranged to provide a variable parabolic lens. The intraocular lens of variable optical power according to claims 1 to 7, characterized in that the lens comprises drive means including a substantially rigid connecting element connected at its first side to an optical element for driving at least one of the optical elements for performing a movement relative to the other optical element, and positioning means for positioning the optical elements in the eye, including a flexible connecting component connected at its first side to the optical element at one end of the optical element opposite the rigid connecting component, the optical elements being adapted to move in tandem with the ciliary muscle of the eye. Variable optical power intraocular lens according to claim 8, characterized in that there is an Ω-shaped structure in each of the flexible connection components and in that the optical elements form a lens with the weakest optical dioptric power in their most overlapping position and a lens with the strongest optical dioptric power in their least overlapping position or that the optical elements form a lens with the strongest optical dioptric power in their most overlapping position and a lens with the weakest optical dioptric power in their least overlapping position. The intraocular artificial lens according to any one of claims 1 to 9, characterized in that the Ω-shaped structures comprise stop shoulders. An intraocular artificial lens according to any one of claims 1 to 8, characterized in that the positioning means are adapted to urge the optical elements to a rest position when the drive means are inactive and in that the optical elements exhibit optical power in the rest position that is associated with near or far vision. An intraocular artificial lens according to any one of claims 1 to 11, characterized in that the side of the rigid and flexible connecting elements, respectively, which is opposite the side connected to the optical element, is secured with anchors which are designed to move in tandem with the ciliary muscle. An intraocular artificial lens according to any one of claims 1 to 12, characterized in that the positioning means are adapted to adjust the rest position of the optical elements after implantation. An intraocular artificial lens according to any one of claims 1 to 13, characterized in that the positioning means comprise an element whose size is adjustable. An intraocular lens according to any combination of the preceding claims, characterized in that the lens is arranged to provide a combination of fixed refractive correction and accommodation to the aphakic eye into which the lens is subsequently implanted. An intraocular lens according to any combination of claim 15, characterized in that the lens is adapted to be implanted in the capsule pocket of the eye. An intraocular lens according to any combination of claim 15, characterized in that the lens is adapted to be implanted in the capsule pocket of the eye. An intraocular lens according to any combination of claim 15, characterized in that the lens is adapted to be implanted in the sulcus of the eye. An intraocular lens according to any combination of claim 15, characterized in that the lens is adapted to be implanted in the iris of the eye.