Corneal transplant allograft reaction: possible predisposing factors.

A series of 869 PKs was reviewed to determine the incidence of allograft reactions in the presence or absence of possible predisposing factors. The average follow-up time after PK was 46 months. The possible predisposing factors studied were mild and severe preoperative vascularization, postoperative neovascularization, synechiae, and inflammation. Other factors considered were bilateral grafts, repeat grafts, and recipient's age. Although there was a significantly higher incidence of allograft reactions in the group with possible predisposing factors compared with the group with none of these, a cause-and-effect relationship could not be established for each possible predisposing factor when considered individually. Most of these factors were usually encountered in combinations of two or more, creating a large number of small variables with less statistical significance in predicting first and second reactions. The incidence of second reactions was similar in the presence or absence of these factors, approximately 25%. Only postoperative synechiae and neovascularization had some significance in eventually leading to permanent graft rejection. The incidence of allograft reaction was also similar among patients with repeat grafts and bilateral grafts. There was an insignificant tendency for the incidence of reactions to decrease in older patients, whether possible predisposing factors were present or not. Final visual acuity was comparable between the group having allograft reactions and the total group. The allograft rejection reaction continues to be the most important cause of graft failure. The role of donor-recipient antigen matching was briefly reviewed.