Biological response to a supraDescemetic synthetic cornea in rabbits.

Objective: To evaluate the biocompatibility of a novel nonpenetrating keratoprosthesis (supraDescemetic synthetic cornea) in a rabbit model.

Methods: Seven rabbits received a supraDescemetic synthetic cornea (7-mm diameter, 350-microm-thick optical zone, 100-microm-thick peripheral flange) in their healthy right eyes. A surgical technique was developed that allowed implantation of the device on top of the bare Descemet membrane. Three rabbits received a supraDescemetic synthetic cornea made of hydroxyethyl methacrylate-methyl methacrylate(26), 1 received a hydroxyethyl methacrylate-N-vinyl pyrrolidone(75) mesoplant, and 3 were implanted with devices made of polymethyl methacrylate. All rabbits were euthanized after 8 weeks; the eyes were enucleated and examined by conventional histological and immunohistochemical evaluations.

Results: All eyes became quiet within several days. The Descemet membrane remained transparent during the observation period. Indirect ophthalmoscopy performed through the prosthesis allowed accurate examination of the posterior pole. Histological evaluation of the implanted corneas displayed no signs of an acute or chronic inflammatory reaction to the supraDescemetic synthetic cornea in 5 eyes; a few inflammatory cells were detected in the corneas of 2 rabbits. The interface between the Descemet membrane and the mesoplant displayed ingrowth of very thin (<10-microm) tissues colonized by keratocytes in 3 of the 7 corneas.

Conclusions: This study validates the biocompatibility of this new type of nonpenetrating keratoprosthesis. Because opening of the anterior chamber is not required with the supraDescemetic synthetic cornea, the risk for intraocular infection is minimal, and the implantation procedure is less traumatic compared with a penetrating device.