BIOCOMPATIBILITY OF A NON–PENETRATING KERATOPROSTHESIS (SUPRADESCEMATIC SYNTHETIC CORNEA, sDSC) IN VASCULARIZED RABBIT CORNEAS

Abstract

Abstract: : Purpose: To assess feasibility and biocompatibility of a lamellar, non–perforating synthetic cornea implanted in rabbit eyes following a corneal injury. Methods: Corneal vascularisation and scarring was induced in the right eye of 15 rabbits by application of 1–heptanol and complete surgical removal of the limbus. Implantation of an sDSC (7mm diameter, 450µm thick optical zone, 100µm thick outer flange) was performed after 45 ± 5 days. The KPro’s were implanted with their central optic part positioned on a completely exposed Descemet’s membrane (DM), the outer flange was located in deep stroma (85%). 3 different materials were tested: hydrophobic PMMA (n=5), hydrophilic HEMA–MMA (n=5) and HEMA–NVP (n=5), with a water content of 34% and 75%, respectively. The corneal surface was covered with a conjunctiva–Tenon flap. Central flap trephination was performed after 63 ± 7 days. Degree of DM vascularisation and scarring was assessed after flap opening and weekly thereafter. Results: In all 15 consecutive cases implantation of the sDSC could be completed successfully without perforation of DM. Repair of the conjunctival flap had to be performed in 5 rabbits. Four months after surgery, 3 of the 5 corneas (60%) with a PMMA implant and 3 of the 5 (60%) with a HEMA–NVP75 implant retained central transparency, the others had developed neovascularisation in the DM–KPro optic interface. All corneas (100%) that received an sDSC made of HEMA–MMA34 displayed a complete clear DM without any vessels or scarring. DM was found firmly attached to the posterior surface of the optic. Conclusions: Implantation of a non–perforating synthetic cornea on top of an exposed DM is feasible. Regarding maintenance of DM transparency HEMA–MMA34 showed the most promising results. As opening of the anterior chamber is not required, a lamellar supraDescemetic Synthetic Cornea would theoretically have less risks and complications than a penetrating KPro.

Keywords: keratoprostheses • cornea: basic science • anterior segment