Blindness and prognostic factors after trabeculectomy with mitomycin C in patients with open-angle glaucoma with long-term follow-up

To determine the long-term blindness rate and related prognostic factors in eyes with open-angle glaucoma after trabeculectomy using adjunctive mitomycin C (MMC).

The retrospective cohort study included 714 eyes from 714 patients with open angle glaucoma who underwent trabeculectomy using MMC. We defined blindness based on the World Health Organization (WHO) criteria as best-corrected visual acuity (BCVA) <20/400 and/or central visual field <10°. We used Kaplan-Meier analysis to estimate the nonblindness rate postsurgery.

Preoperatively, the mean (standard deviation) BCVA, intraocular pressure (IOP) and mean deviation (MD) using the central 30-2 program of Humphrey Field Analyser were 0.11 ± 0.31, 20.5 ± 7.1 mmHg, and -16.93 ± 7.16 dB. The follow-up period was 11.7 ± 7.3 years, and the mean postoperative IOP reduction rate was 41.4% ± 20.2%. The 10- and 20-year cumulative survival rates were 87.8% and 82.6%. The survival rates were significantly higher in the groups with better preoperative BCVA, preserved preoperative MD, and higher mean postoperative IOP reduction rate (all p < 0.001). Moreover, the analysis of prognostic factors for blindness showed that the multivariate hazard ratios for preoperative BCVA, preoperative MD and mean postoperative IOP reduction rate were 4.74, 0.92 and 0.97, respectively (all p < 0.001).

One-eighth and one-sixth of the eyes became blind at 10 and 20 years post-trabeculectomy using MMC. Preoperative severe visual impairment and visual field loss and postoperative nonsustained IOP reduction were identified as independent prognostic factors leading to blindness.