This invention relates to an intraocular lens with a transparent central area and an iris diaphragm adjacent to it radially for correcting or covering an aniridia.
Eye injuries often lead to injury to the iris, so there is a comparatively high demand for intraocular lenses with iris diaphragms.
Such lenses available on the market today have a two-part design with a diaphragm of black polymethyl methacrylate designed like a ring. A lens of transparent polymethyl methacrylate is secured or held mechanically in the opening in the diaphragm.
These lenses have proven successful in practice.
However, since these lenses have a comparatively limited flexibility, a relatively large surgical opening must be created for implantation of the lens in the eye, so that healing of the eye takes a relatively long time.
In addition, it is also desirable for the optical appearance of the diaphragm of the implanted lens to approximate even more closely the natural iris. However, it is extremely cost-intensive to use differently colored materials for the iris diaphragms with these known lenses. If instead of this, a pigment is applied to the black iris diaphragm, e.g., by painting or printing, there may be toxicological risks or problems with regard to long-term stability.
U.S. Pat. Nos. 4,955,904 and 5,622,706 disclose masked intraocular lenses, where the masking serves to correct imaging defects of the eye, not to replace an iris. According to U.S. Pat. No. 4,955,904, pigments which serve to form the mask may be embedded in the lens.
The object of this invention is to create an improved lens for treatment of aniridia. unit, whereby the diaphragm consists essentially of an opaquely pigmented film which is embedded in an outer area which is connected in one piece to the central area of the lens and is completely sheathed by transparent lens material.
The object is achieved according to this invention by the fact that the lens and the diaphragm are designed as a one-piece unit, whereby the diaphragm consists essentially of a flexible, opaquely pigmented film which is embedded in an outer area which is connected in one piece to the central area of the lens and is completely sheathed by transparent lens material, and where the multi-layer film has an inner pigment carrier layer and a barrier layer which completely seals and encloses the pigment carrier layerxe2x80x94even at the edges of the layerxe2x80x94and is resistant to diffusion of the pigments.
According to an especially preferred embodiment of this invention, the film may be designed in multiple layers and may have an inner pigment carrier layer, which can preferably be designed to be colored by printing technology, and a barrier layer which seals and sheaths the pigment carrier layer completelyxe2x80x94even at the edges of the layerxe2x80x94and makes it resistant to diffusion of the pigments.
In this embodiment, the transparent lens material enclosing the multi-layer film serves primarily only to guarantee a good biological tolerability of the lens in the eye, while the barrier layer on the film is responsible for sealing the pigments.
In addition, this embodiment offers the special advantage that conventional water-absorbent hydrophilic materials which are conventionally used for foldable (soft) lenses can readily be used as the transparent lens material, so that a foldable intraocular aniridia lens can now be produced for the first time.
A copolymer of methyl methacrylate and 2-hydroxyethyl methacrylate is preferably used as the transparent lens material. This material optimizes the foldability and water retention of the lens during surgical implantation in the eye and at the same time ensures the long-term stability in the biological medium as well as the optical quality. In addition, this material is heat-resistant and is suitable for sterilization with steam.
In particular, if the lens material is highly hydrophilic and absorbs water, the barrier layer should preferably consist of a hydrophobic material, e.g., silicone. Thus, diffusion of pigments can be reliably prevented. In addition, silicone also remains stable even in steam sterilization of the lens.
The primary carrier film is preferably made of a heat-resistant material suitable for the desirable steam sterilization of the lens, such as polypropylene and/or polyimide in particular, and is printed with a colored pattern corresponding to that of a natural iris, e.g., by screen printing.
In addition, with regard to preferred features of this invention, reference is made to the claims as well as the following description of the drawings, on the basis of which the especially preferred embodiment of the lens according to this invention and its production are described in greater detail.