Two-year randomized controlled trial of circumferential versus segmental ab externo angle surgery in patients with...

To compare the surgical outcomes of visco-circumferential-suture-trabeculotomy (VCST) and rigid probe segmental viscotrabeculotomy (VT) in primary open-angle glaucoma (POAG).

A prospective randomized controlled study.

Patients presenting with POAG and operated upon in Mansoura Ophthalmic Center in Mansoura, Egypt between February 2017 and September 2021 were enrolled. Study eyes were randomized to either VCST or VT and follow up extended for 24 months. Success was defined as an intra ocular pressure (IOP)≤18 mmHg with a 40% reduction from baseline. Complications were noted.

The study enrolled 166 (82 in the circumferential group) eyes of 107 patients. There were no statistically significant differences between both groups in any demographic or preoperative clinical characteristics. The IOP trend demonstrated marked initial reduction (from 32.3±2.4 and 31.8±2.6 mmHg preoperatively in VCST and VT groups respectively) followed by a slow gradual rise over subsequent follow-up settling at lower IOP values in the circumferential (12.4±1.2 mmHg) than in the segmental group (15.5±0.9 mmHg) (p<0.001), both settling at significantly lower levels than preoperative values. The survival curve demonstrates complete success rates at 12, 15, 18, and 24 months were 98.8%, 96.4%, 95.1%, and 85.4% in the circumferential group and 98.8%, 92.9%, 91.7%, 79.8% in the segmental group respectively. Minimal self-limiting hyphema was universal in all study eyes.

Angle procedures -segmental and circumferential- are effective in lowering the IOP for at least 2 years in eyes with POAG, with circumferential angle surgery providing a greater reduction of IOP and requiring fewer subsequent glaucoma procedures.