Purpose: To determine the effect of bilateral surgery on the rejection-free survival of penetrating keratoplasties (PK) performed for keratoconus.
Methods: The records of 587 patients with a PK for keratoconus who attended a single center over a 7-year period were reviewed. Details 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 contralateral PK on graft survival was evaluated using actuarial methods.
Results: In first grafts for all patients, there was an increased rate of graft 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 who had bilateral grafts, a graft to the contralateral eye increased the 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 < 0.001), but overall the second eye had a significantly lower risk of rejection when compared with either the first grafted eye or unilaterally grafted eyes (P < 0.001). The risk to the second grafted eye further reduced as the interval between the surgeries increased.
Conclusions: In keratoconus, the diameter of the host trephine, severe allergic eye disease, and a graft surgery to the contralateral eye determine the risk of rejection in the index eye. The reasons the second grafted eye of patients receiving bilateral PKs appears to have an enhanced rejection-free survival are discussed.