Keratoprosthesis

DETAILED DESCRIPTION The present invention overcomes the drawbacks of the prior art by providing a keratoprosthesis which, when implanted, becomes an integral part of the eye, is adequately supported therein and is virtually impossible to extrude.
In its simplest form, the keratoprosthesis of the invention comprises a generally cylindrical lens structure, preferably of solid construction, and an anterior chamber supporting means.
The lens structure is of sufficient length to extend anteriorly into the corneal stroma and posteriorly through the pupil and into the posterior chamber.
Because the lens structure extends into the posterior chamber, corneal membrane tissue growth occurring subsequent to the implant procedure cannot interfere with the transmission of light through its posterior end.
The lens structure is supported at two separate places; anteriorly by attachment to the corneal stroma and posteriorly by the anterior chamber supporting means, which is anchored by the contact of its outer edges with the anterior chamber angle.
Preferably, the anterior chamber supporting means is substantially planar and is of such dimensions and of such shape as to permit it to be torsionally anchored in the anterior chamber by means of contact of its outer edges with the anterior chamber angle.
A preferred embodiment of the invention includes a lens structure having an anteriorly removable lens element which can be either replaced or exchanged for another element of differing dioptic power without surgical intrusion into the anterior chamber.
Preferably, in such an embodiment, the cylindrical lens structure has an axially disposed internally threaded receptacle for receiving the removable lens portion, which itself has a threaded external surface.
Thus, the lens portion is readily screwed in or out of the receptacle without the necessity of altering or exchanging the cylindrical lens structure itself by surgical means.
To facilitate the removal and replacement of such a threaded lens element, one or more channels, ridges or other variations from the smooth rounded anterior surface of the lens element are preferably provided for accommodating a tool adapted to engage these surface articulations