TISSUE INTERACTION WITH HYDROGEL SPONGES IMPLANTED IN THE RABBIT CORNEA

We proposed poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel sponges as potential materials for the peripheral zone of a composite keratop rosthesis. It was previously shown that such sponges allowed cellular invasion when implanted s.c. in rabbits. To evaluate the reaction elic ited by these materials in the corneal tissue, a PHEMA sponge, with po re size diameters of 10-30 mum, was produced, impregnated with collage n, and implanted in the rabbit cornea in both central and limbal regio ns of separate eyes. The eyes were examined by slit-lamp biomicroscopy up to 6 months postoperatively. Enucleation was performed at 3 weeks, 6 weeks, and 6 months, then excised implants were examined by light a nd transmission electron microscopy. Both clinical and histopathologic al examination indicated that sponges were well tolerated by the strom al and limbal tissues. No capsule was formed around any of the implant s. Corneal fibroblasts and capillaries readily invaded the internal vo ids in the sponge to all depths. The invading cells remained viable an d active up to the end of the follow-up period. Our findings suggest t hat hydrophilic PHEMA sponges may be successful as peripheral keratopr osthetic materials able to provide a permanent and tight fusion of the keratoprosthesis with the host tissue.