Intermediate Outcomes of a Novel Standalone Ab Externo SIBS Microshunt With Mitomycin C

Purpose: To determine the efficacy, risk factors for failure, and adverse events of a standalone novel ab externo SIBS microshunt with mitomycin C (MMC) during 1-year follow-up.

Design: Retrospective, interventional case series.

Subjects: Glaucomatous eyes with an intraocular pressure (IOP) above target and/or progressing on maximally tolerated medical therapy.

Methods: Consecutive patients with open-angle glaucoma (OAG) and no previous filtering surgery received an ab externo SIBS microshunt with MMC from July 2015 to November 2017. Main outcome measures were proportion of eyes at 1-year with (1) no 2 consecutive IOP readings >17 mm Hg or clinical hypotony without (complete) or with glaucoma medications (qualified); and (2) at least a 20% reduction from decision IOP. Secondary outcomes included upper IOP thresholds of 14 mm Hg and 21 mm Hg with and without a 20% IOP reduction from baseline, median IOP, medications, risk factors for failure, interventions, complications, and reoperations.

Results: A total of 164 eyes in 132 patients were included. Complete success was achieved in 76.9% of eyes, qualified success in 92.5%. Complete success was 75.6% for an upper IOP cut-off of 14 mm Hg and 76.9% for 21 mm Hg, and qualified success was 91.9% and 92.5%. MMC dose of 0.2 vs 0.4-0.5 mg/mL (hazard ratio [HR] 2.51; 95% CI 1.12-5.65) and primary open-angle glaucoma vs secondary open-angle glaucoma (SOAG) (HR 2.51; 95% CI 1.01-6.23) represented the only risk factors for failure in multivariable analysis. Needling was performed in 8.5% of eyes. Two eyes received surgical revision, and 1 a reoperation.

Conclusions: One-year results of the ab externo SIBS microshunt demonstrated promising rates of qualified and complete success, decreased drop use, few complications, and infrequent postoperative interventions.