Pilocarpine-associated allograft rejection in postkeratoplasty patients

Corneal allograft rejection is a major cause of graft failure. Identifying possible risk factors for rejection may improve chances for successful outcome. We report three cases of graft rejection associated with the use of post-operative pilocarpine at different concentrations. Pilocarpine was used to treat persistent epithelial defects or raised intraocular pressure. The patients were managed until their rejection episodes resolved. In each case, graft rejection ensued in a quiet eye after initiating treatment with pilocarpine, without other change in medications. Each graft rejection episode resolved with discontinuation of pilocarpine and administration of prednisolone acetate. We propose that if pilocarpine does indeed diminish corneal allograft immune privilege and enhance graft rejection, the mechanisms may include induced intraocular inflammation and altering of anterior chamber associated immune deviation. This is the first report implicating a topical ophthalmic medication with possible corneal allograft rejection.