[2nd generation bio-integrated keratoprosthesis. Implantation in animals]

Our goal was to evaluate a second generation biointegrable keratoprosthetic device (BioKpro II).

The device consists of a porous transparent PTFE (12 mm diameter) and a soft copolymer structure for the optical system (7 mm diameter). Intraocular pression was evaluated with a Goldmann tonometer on an artificial chamber. A lamellar dissection was carried out 3 mm radially for 360 degrees creating a pocket to accommodate the skirt. The soft optic (42.5 D; 500 microns thick) was positioned through a hole (6 mm in diameter) trephined in the central cornea. A 360 degrees peritomy was performed and conjunctiva was placed in front of the prosthesis, sutured and was opened 15 days post implantation. 14 rabbits were implanted and were allowed to heal for three months.

We are able to measure the intraocular pressure by Goldmann tonometer on an artificial chamber. We did not observed epithelialisation on the hydrophilic optical surface (14/14). Aseptic necrosis in direct contact between cornea and the soft optical system was observed when conjunctiva was not effective (4/14). As observed with the first generation devices, conjunctiva or buccal mucosa is needed to avoid local necrosis. In other cases no adverse reactions were observed after implantation.

The geometry and biomechanical properties of the BioKpro II is closed to that of the human cornea. The junction between the optical and the flange was bound by polymeric interpenetration and prosthesis dislocation was not seen under pressure over 1000 mmHg.

Second generation biointegrable keratoprostheses (BioKpro II) can be implanted successfully. Further tests will determine if surface modifications designed to promote epithelial cell attachment on the optical system could prevent ulceration at the junction between the fluorocarbon and the core.