Suppression of corneal allograft rejection by systemic cyclosporine-A in heavily vascularized rabbit corneas following alkali burns.

Immunologic rejection is the main cause of corneal graft failure, especially in vascularized corneal beds. The purpose of this study was to investigate the effect of systemic Cyclosporine-A (CsA) on the survival of corneal allografts in heavily vascularized rabbit corneal beds, following alkali burn. Heavy corneal vascularization was induced in one eye of 20 rabbits by alkali burn. Forty-five days later, penetrating keratoplasty was performed in all the heavily vascularized corneas. Twenty-five mg/kg/day of CsA was intramuscularly administered to 10 rabbits for 30 days. The other 10 rabbits were treated with the solvent without CsA and were used as a matched control group. The results show a significant difference in corneal allograft survival between the two groups. All corneal grafts in the untreated group were intensely rejected and vascularized within 3 weeks. Nine of the 10 corneal transplants, in the CsA-treated group, remained transparent without signs of immunologic rejection for > 180 days. In one corneal transplant, minor signs of rejection occurred. We suggest that CsA, when given systemically, is a potent drug in the prevention of immunologic rejection in high-risk corneal transplantations, such as allografts, in heavily vascularized corneas following alkali burn.