BILATERAL PENETRATING KERATOPLASTY FOR KERATOCONUS

Purpose: To determine the effect of bilateral surgery on the rejection -free survival of penetrating keratoplasties (PK) performed for kerato conus. Methods: The records of 587 patients with a PK for keratoconus who attended a single center over a 7-year period were reviewed. Detai ls on 400 patients were sufficiently complete to permit a multivariate analysis of the factors suspected to influence graft survival. In 165 of these patients with bilateral grafts, the effect of a contralatera l PK on graft survival was evaluated using actuarial methods. Results: In first grafts for all patients, there was an increased rate of graf t rejection with a host trephine greater than 7.50 mm in diameter and in patients with severe allergic eye disease (P < 0.01). In patients w ho had bilateral grafts, a graft to the contralateral eye increased th e risk of rejection in the first eye to be grafted, and although this effect reduced with time, it was still present after an interval of up to 6 years between surgeries. A rejection episode in the first eye to be grafted increased the risk of rejection in the second eye (P < 0.0 01), but overall the second eye had a significantly lower risk of reje ction when compared with either the first grafted eye or unilaterally grafted eyes (P < 0.001). The risk to the second grafted eye further r educed as the interval between the surgeries increased. Conclusions: I n keratoconus, the diameter of the host trephine, severe allergic eye disease, and a graft surgery to the contralateral eye determine the ri sk of rejection in the index eye. The reasons the second grafted eye o f patients receiving bilateral PKs appears to have an enhanced rejecti on-free survival are discussed.