To investigate whether mitomycin C (MMC) results in an improved trabeculectomy outcome in primary open-angle glaucoma patients who preoperatively used prostaglandin (PG) ophthalmic solution.

The subjects consisted of three groups of primary open-angle glaucoma patients who underwent trabeculectomy. Group A consisted of 17 patients who did not use PG ophthalmic solution preoperatively, while Group B consisted of ten patients who used PG ophthalmic solution for at least three months but were not treated with MMC during the operation, and Group C consisted of 14 patients who used PG ophthalmic solution for at least three months and were treated with MMC during the operation. The operation was considered successful when the intraocular pressure ranged from 6 to 18 mmHg, regardless of application of ocular hypotensive agents.

Four years after the operation, differences of the cumulative success rate between Group A and B ( p = 0.008) and between Group B and Group C ( p = 0.036) were statistically significant, but differences between Group A and C were not ( p = 0.813) (Log rank test results).

The cumulative success rate of trabeculectomy in primary open-angle glaucoma patients who used PG ophthalmic solution for at least three months was lower than that of patients who did not use PG ophthalmic solution. However, the intraoperative administration of MMC increased the cumulative success rate of trabeculectomy in patients who did use PG ophthalmic solution for at least three months to a level similar to patients who did not use PG ophthalmic solution.