Fabrication of a keratoprosthesis.

For patients with opaque corneas that have a poor prognosis when using regular corneal transplants, a clear plastic "window" in the form of a keratoprosthesis may offer the only hope of usable vision. Various forms of such devices have been used for many years with varying degrees of success. The design, fabrication, and optical testing of two variations of a polymethylmethacrylate (PMMA) keratoprosthesis are described. Type 1 consists of a twin-plate collarbutton-style design that is used in eyes that have sufficient tear fluid production to maintain wetting of the anterior surface of the eye. Type 2 is of a similar design, with an added anterior cylinder that protrudes through a permanently closed eyelid, and is used in end-stage dry eyes.