Trabeculectomy for neovascular glaucoma in proliferative diabetic retinopathy, central retinal vein occlusion, and ocular ischemic syndrome: Surgical outcomes and prognostic factors for failure

Purpose To evaluate the outcomes of trabeculectomy in the eyes with neovascular glaucoma (NVG), caused by proliferative diabetic retinopathy (PDR), central retinal vein occlusion (CRVO), and ocular ischemic syndrome (OIS). Methods A retrospective review of NVG eyes that underwent trabeculectomy between 1991 and 2019. Complete success was defined as intraocular pressure (IOP) between 6 and 21 mmHg without antiglaucoma medications (AGM). The risk factors were analyzed by Cox's proportional hazard model. Results The study included 100 eyes of 100 subjects with a mean age of 58 ± 9.8 years and a median follow-up of 1.27 years (interquartile range: 0.63, 2.27). The cause of NVG was PDR in 59 eyes (59%), CRVO in 25 eyes (25%), and OIS in 16 eyes (16%). Trabeculectomy with mitomycin-C was performed in 88 eyes and trabeculectomy in 12 eyes. The cumulative complete success probability of trabeculectomy in PDR was 50% (95% confidence interval [CI]: 38, 65) at 1 year, 8% (1, 46) at 3-5 years. In OIS, it was 64% (43, 96) from 1 to 5 years. In CRVO, it was 75% (59, 94) at 1 year, 45% (23, 86) from 2 to 5 years. The PDR was associated with a higher risk of surgical failure compared to OIS (P = 0.04) and CRVO (P = 0.004). Other significant risk factors were increasing age (P = 0.02), persistent neovascularization of iris (NVI) (P = 0.03), higher number of anti-vascular endothelial growth factor (VEGF) injections prior to trabeculectomy (P = 0.02), and delay in performing trabeculectomy (P = 0.02). Conclusion Compared to CRVO and OIS, the eyes with NVG secondary to PDR had poor success with trabeculectomy. Older age, persistent NVI, need for a higher number of anti-VEGF injections, and delayed surgery were associated with a higher risk for trabeculectomy failure.