Comparison of failure rates of orthotopic corneal grafts using three different grafting procedures.

The fate of orthotopic, allogeneic corneal grafts was followed in inbred rats following three different grafting procedures. Corneas were grafted to recipient rats either in an intralamellar pocket, on a deep stromal bed or by penetrating keratoplasty. In all cases the donor cornea consisted of all three tissue layers (epithelium, stromal and endothelium). Recipient corneas were pretreated with lipopolysaccharide to induce neovascularization. In all three experimental groups, allogeneic grafts went through a phase which clinically resembled a rejection. This phase was characterized by the development of vessels into the transplanted cornea, and opacification. This phase peaked at between 2 and 3 weeks after which some of the grafts cleared and the vascularization receded. Approximately 65% of grafts placed on a deep stroma bed cleared and were considered successful while only 30-35% of the grafts placed in intralamellar pockets or in full-thickness defects were deemed successful. Histological observations paralleled these clinical impressions.