Ab Interno Trabeculectomy Versus Trabeculectomy for Open-Angle Glaucoma

Purpose: To compare the effect of ab interno trabeculectomy with trabeculectomy. Design: Retrospective, cohort study. Participants: A total of 115 patients who underwent ab interno trabeculectomy (study group) compared with 102 patients who underwent trabeculectomy with intraoperative mitomycin as an initial surgical procedure (trabeculectomy group). Inclusion criteria were open-angle glaucoma, age >= 40 years, and uncontrolled on maximally tolerated medical therapy. Exclusion criterion was concurrent surgery. Methods: Clinical variables were collected from patient medical records. Main Outcome Measures: Intraocular pressure (IOP) and Cox proportional hazard ratio (HR) and Kaplan-Meier survival analyses with failure defined as IOP >21 mmHg or less than 20% reduction below baseline on 2 consecutive follow-up visits after 1 month; IOP <= 5 mmHg on 2 consecutive follow-up visits after 1 month; additional glaucoma surgery; or loss of light perception vision. Secondary outcome measures include number of glaucoma medications and occurrence of complications. Results: Mean follow-up was 27.3 and 25.5 months for the study and trabeculectomy groups, respectively. Intraocular pressure decreased from 28.1 +/- 8.6 mmHg at baseline to 15.9 +/- 4.5 mmHg (43.5% reduction) at month 24 in the study group, and from 26.3 +/- 10.9 mmHg at baseline to 10.2 +/- 4.1 mmHg (61.3% reduction) at month 24 in the trabeculectomy group. The success rates at 2 years were 22.4% and 76.1% in the study and trabeculectomy groups, respectively (P < 0.001). Younger age (P = 0.037; adjusted HR, 0.98 per year; 95% confidence interval [CI], 0.97-0.99) and lower baseline IOP (P = 0.016; adjusted HR, 0.96 per 1 mmHg; 95% CI, 0.92-0.99) were significant risk factors for failure in the multivariate analysis of the study group. With the exception of hyphema, the occurrence of postoperative complications was more frequent in the trabeculectomy group (P < 0.001). More additional glaucoma procedures were performed after ab interno trabeculectomy (43.5%) than after trabeculectomy (10.8%, P < 0.001). Conclusions: Ab interno trabeculectomy has a lower success rate than trabeculectomy. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references. Ophthalmology 2012; 119: 36-42 (C) 2012 by the American Academy of Ophthalmology.