Keratoprosthesis

An artificial cornea implanted to restore vision in an eye whose own cornea has become so scarred or damaged that a conventional donor corneal transplant cannot succeed or has already failed, most often built around a clear plastic optical cylinder held in place by a surrounding skirt or supporting structure. Because a donor transplant depends on the eye's own tissue accepting and nourishing the new corneal tissue, an eye with severe scarring, dryness, or a badly damaged surface may reject transplant after transplant, leaving an artificial device as the remaining option to restore any vision at all. Experimental designs for an artificial cornea were attempted from the nineteenth century onward, but early versions were prone to complications such as infection, leakage, or the device working loose, and it was only through decades of refinement of the plastics, surgical techniques, and after-care involved that later designs, such as the type introduced in the United States in the 1990s, achieved a survival and success rate good enough for routine use in appropriate patients. Recipients require lifelong follow up and, in most designs, an artificial protective contact lens worn continuously over the device, since the plastic optical core does not have the natural cornea's ability to heal or resist infection on its own.