Ab-Externo MicroShunt versus Trabeculectomy in Primary Open-Angle Glaucoma:One-Year Results from a 2-Year Randomized, Multicenter Study

Purpose: To compare the effectiveness and safety of the MicroShunt versus trabeculectomy in patients with primary open-angle glaucoma (POAG). Design: One-year results from a 2-year, prospective, randomized, multicenter, noninferiority study (NCT01881425) conducted in the United States and Europe. Participants: Eligible patients were aged 40-85 years with intraocular pressure (IOP) >15 and 20% reduction in mean diurnal IOP from baseline (no medication washout) at year 1 without increasing the number of glaucoma medications. Secondary effectiveness end points at year 1 were the mean IOP change from baseline and requirement for postoperative intervention. Additional end points included glaucoma medication use and adverse events. Results: Overall, 395 (MicroShunt) and 132 (trabeculectomy) patients were randomized (mean Humphrey visual field mean deviation, -12.34 decibels [dB]). At year 1, probability of success was lower in the MicroShunt group compared with the trabeculectomy group (53.9% vs. 72.7%, respectively; P < 0.01). In the MicroShunt group, mean IOP +/- standard deviation decreased from 21.1 +/- 4.9 mmHg at baseline to 14.3 +/- 4.3 mmHg (-29.1%; P < 0.01) at year 1, with a mean of 0.6 +/- 1.1 glaucoma medications (baseline 3.1 +/- 1.0; P < 0.01). In the trabeculectomy group, mean IOP decreased from 21.1 +/- 5.0 mmHg to 11.1 +/- 4.3 mmHg (-45.4%; P < 0.01), with a mean of 0.3 +/- 0.9 glaucoma medications (baseline 3.0 +/- 0.9; P < 0.01). Postoperative interventions, including laser suture lysis, were reported in 40.8% (MicroShunt) versus 67.4% (trabeculectomy) of patients (P < 0.01). Reported incidence of transient hypotony was higher in the trabeculectomy group versus the MicroShunt group (49.6% vs. 28.9%; P < 0.01). Vision-threatening complications were uncommon and reported in 1.0% of MicroShunt versus 0.8% of trabeculectomy patients. Conclusions: Probability of success was lower with MicroShunt compared with trabeculectomy. Although reductions in IOP and glaucoma medications over 1 year were observed in both groups, the trabeculectomy group had a lower mean IOP on fewer medications. Ophthalmology 2021;128:1710-1721 (c) 2021 by the American Academy of Ophthalmology. This is an open access article under the CC BY-NC-ND license (http://creativecommons. org/licenses/by-nc-nd/4.0/).