Viscocanalostomy versus trabeculectomy for primary open angle glaucoma: 4-year prospective randomized clinical trial

Abstract

The purpose of this randomized clinical trial was to compare the effectiveness and safety of viscocanalostomy (visco) with trabeculectomy (trab) in the management of primary open angle glaucoma (POAG). Patients were randomized to have a viscocanalostomy (25 eyes) or a trabeculectomy (25 eyes) performed by one surgeon (TDM) and followed up prospectively. Patients were examined preoperatively, at day 1, day 3 if required, day 6, week 2 and thereafter as near as possible to 1, 3, 6, 12, 18, 24, 30, 36, 48, 54, and 60 months. We recorded intraocular pressure (IOP), presence or absence of any complications, presence and description of any bleb, visual acuity with glasses, and full examinations as routine to monitor any progression of the glaucoma. Bleb interventions including needling and antimetabolites were allowed and recorded in both groups. YAG laser goniopuncture was allowed in the viscocanalostomy group. Mean follow-up was 40 months (SD 15), with a range from 6 to 60 months. Forty-two percent (n=10) of the patients in the trabeculectomy group had a successful outcome (IOP<18 mm Hg with no treatment) at last follow-up visit, compared to 21% (n=5) in the viscocanalostomy group. IOP was lower in the trab group with differences in IOP being statistically significant at month 12 (P=<0.001), 24 (P=<0.001), 30 (P=0.030), 36 (P=<0.001), and 48 (P=0.018). The trabeculectomy group required less postoperative topical IOP-lowering medication (P=0.011). In this study, we found trabeculectomy to be more effective at lowering IOP than viscocanalostomy in POAG patients.