A 2-Year, Single-Center Study to Assess the Safety and Effectiveness of the MicroShunt in Primary Open-Angle Glaucoma

The aim of the study was to assess the effectiveness and safety of the MicroShunt (formerly known as the MIDI-Arrow or InnFocus MicroShunt®), an 8.5-mm-long, 70-μm lumen-controlled ab externo glaucoma filtration surgery device made from poly(styrene-block-isobutylene-block-styrene) (SIBS), in patients with primary open-angle glaucoma (POAG).

A 2-year, single-center, single-surgeon, nonrandomized, adaptive feasibility clinical study (NCT01563237) was conducted in France from June 2011 to November 2016. Eligible patients were aged 18-85 years and had POAG inadequately controlled on maximum tolerated medical therapy with intraocular pressure (IOP) ≥18 and ≤40 mm Hg. The MicroShunt was implanted ab externo with adjunctive use of mitomycin C (0.2-0.4 mg/mL applied for 2-3 min), alone or in combination with cataract surgery. The primary effectiveness endpoints were the reduction in IOP relative to the preoperative value assessed at each postoperative visit and the measurement of success at years 1 and 2. The primary safety endpoint was the incidence of all procedure- and/or device-related adverse events (AEs) during the study. The secondary effectiveness endpoint was the mean number of glaucoma medications per patient, and the secondary safety endpoint was the incidence of glaucoma reoperation.

Sixty-one eyes from 61 patients underwent MicroShunt implantation. Mean IOP ± standard deviation (SD) was significantly reduced from 25.7 ± 6.1 mm Hg at baseline (N = 61) to 15.8 ± 4.7 mm Hg at year 1 (n = 58) and 16.5 ± 6.0 mm Hg at year 2 (n = 52) (both p < 0.001). Overall success rates for patients achieving IOP ≥6 mm Hg and <21 mm Hg at year 1 and year 2 were 80.3% and 75.4%, respectively. Mean ± SD number of glaucoma medications per patient decreased significantly from 2.9 ± 1.1 at baseline to 0.6 ± 1.0 at year 1 (n = 58) and 1.0 ± 1.3 at year 2 (n = 52) (both p < 0.001). The most common procedure- and/or device-related AEs were investigator-reported increased IOP and hyphema. Four patients required reoperation.

In this study, sustained reductions in mean IOP and number of glaucoma medications from baseline were observed up to 2 years post-surgery. No long-term, sight-threatening AEs were observed.