A corneal graft–keratoprosthesis is an artificial clear central corneal window surrounded by a human donor cornea. Implantation is generally done if a standard corneal transplant has failed, or when it is inappropriate. The procedure is used to treat only the most severe corneal opacity.
A type I corneal graft–keratoprosthesis is the most commonly implanted artificial corneal device and is suitable for patients whose blink and tear mechanisms are reasonably intact (wet blinking eyes) and who have had multiple graft failures. The device is custom‑made to have a range of dioptric powers to match the axial length of the patient's aphakic eye. It is shaped like a collar button, with a refractive front and porous back plate and a titanium locking ring.
Implantation of the fully assembled corneal graft–keratoprosthesis is done under general or local anaesthesia. A human donor corneal graft with a central hole is positioned between the front and back plate, and held in place by the titanium ring. The central portion of the patient's opaque cornea is removed and if the natural lens is in place, it is also removed. The corneal graft–keratoprosthesis is then transferred to the patient's corneal opening and secured with multiple interrupted sutures. Finally, a soft bandage contact lens is placed on the surface of the eye.
Postoperatively, patients wear a soft contact lens and use prophylactic antibiotic drops for the rest of their lives. In addition, topical steroids are usually recommended and patients need frequent follow‑up and monitoring for life.