Change in visual acuity and associated risk factors after trabeculectomy with adjunctive mitomycin C

Purpose: To report the 5-year incidence of visual impairment after mitomycin C-augmented trabeculectomy (MMC trabeculectomy) and the risk factors for visual impairment. Methods: This is a multicentre prospective observational cohort study. Among glaucoma patients registered in the Collaborative Bleb-related Infection Incidence and Treatment Study performed in Japan, the patients with eyes meeting the following qualifications were included: eyes with primary open-angle glaucoma; eyes with primary angle-closure glaucoma; eyes with exfoliative glaucoma; eyes with ≥3/60 in blindness analysis; and eyes with ≥20/60 in low-vision analysis and visual acuity loss analysis. The patients were followed at 6-month intervals for 5 years. The entry data and follow-up data were analysed to determine the incidence of blindness (<3/60), low vision (≥3/60 and <20/60) and visual acuity loss (≥0.2 logMAR) during the follow-up period. Risk factors for visual impairment were also analysed. Results: A total of 694 eyes of 694 or 559 eyes of 559 glaucoma patients were subjected to the blindness analysis or the low-vision and visual acuity loss analysis, respectively. Visual acuity significantly deteriorated (p < 0.0001): 12.2% (95%CI: 9.8–14.7%) of the patients became blind; 12.1% (95%CI: 9.4–14.9%) were judged to have low vision at the final examination; 28.3% (95%CI: 24.5–32.0%) were judged to have visual acuity loss. Glaucoma subtypes, poor preoperative visual function and postoperative complications are the main risk factors for visual impairment. Conclusions: Visual acuity was significantly reduced after MMC trabeculectomy in 5 years, and we identified several risk factors associated with this complication.