Prior Contralateral Penetrating Keratoplasty Is a Risk Factor for Second Eye Graft Rejection.

Aims: To determine whether prior penetrating keratoplasty (PK) in the contralateral eye increases risk of second eye PK graft rejection.
Methods: Cohort study of 593 consecutive PKs in transplant-naïve eyes (500 unilateral cases, 93 second eyes). Outcomes were compared between PKs performed in eyes with versus without a history of prior contralateral eye PK. Risks of rejection and failure were estimated using Cox proportional hazards models.
Results: Mean age was 53.7 ± 23.3 years; average follow-up was 4.00 ± 2.87 years. Rejection occurred in 211 (35.6%) grafts. The incidence of rejection was 34.0% in unilateral cases and 44.1% in second eyes with PK in the contralateral eye. Prior contralateral PK was a significant risk factor for graft rejection (HR = 1.42, 95% CI 1.01-2.01, p = .045).
Conclusion: Contralateral PK is associated with increased risk of second eye graft rejection. Loss of ocular immune privilege is a possible mechanism.