Retroprosthetic Membrane Formation after Implantation of Experimental Keratoprothesis in Rabbit

ABSTRACT

The studies about factors influencing the retroprostheic membrane formation, one of major complications after keratoprosthesis implantation, and about histological characteristics of the retroprosthetic membrane were performed. The methods to inhibit formation and proliferation of membrane were also tried. Formation of the membrane according to corneal trephination size and the effects of lens removal to membrane formation were studied. The influence by the design of keratoprosthesis was also studied. Corticosteroid and SIMP (synthetic inhibitor of metalloproteinase) were applied topically to see the inhibitory effects of drugs to membrane. To evaluate the postoperative intraocular inflammation. Interleukin-1beta was assessed in the aqueous humor at postoperative 3 weeks. Regardless of trephination size, all trephination sites were replaced with opaque fibrous membranes. Histologically, in small trephination group (under 6mm) the membrane was regeneration of cornea showing corneal stromal fibroblast migration and proliferation and mature collagen. In large trephination group (over 7mm), the periphery of the membrane was compatible with corneal regeneration, but central portion was filled with granulation tissue. The removal of lens didn`t influenced the formation of membrane formation. In disc type keratoprosthesis implantation group, all the implants were extruded within 1 month due to retroprosthetic membrane formation. In cylinder type keratoprosthesis implantation group, the physical barrier of cylinder stopped the retroprosthetic membrane proliferation and spared the posterior surface of optic portion. The implants were not extruded for average 10 weeks. Corticosteroid and SIMP showed the effects of decreasing mature collagen formation in the membrane. The level of Interleukin-1beta at postoperative 3 weeks showed no difference according to different drugs and the highest level was checked in cylinder type keratoprosthesis implantation group.