Intermediate outcomes of SIBS microshunt in cases of refractory and nonrefractory glaucoma

To compare the intraocular pressure (IOP)-lowering, adverse event profile, and risk factors for failure of the SIBS (poly[styrene-block-isobutylene-block-styrene]) microshunt implantation in refractory versus nonrefractory glaucoma.

A multicentre, retrospective interventional cohort study.

A total of 236 glaucoma eyes were analyzed with an IOP above target or progressing on maximal medical therapy. Refractory glaucoma was defined as a history of prior subconjunctival filtering surgery. One-to-one nearest-neighbor matching yielded 118 refractory eyes (111 patients) and 118 nonrefractory eyes (105 patients).

This study evaluated 1-year outcomes of consecutive eyes undergoing ab externo SIBS microshunt implantation with mitomycin-C (MMC) between July 2015 and August 2020.

Primary outcome was surgical success, defined as IOP 6-17 mm Hg with ≥20% reduction, classified as complete (without medications) or qualified (with medications). Secondary outcomes included success at IOP thresholds 14 and 21 mm Hg, median IOP, medication burden, risk factors for failure, and postoperative complications, interventions, and reoperations.

Complete success was lower in refractory compared with nonrefractory eyes (63.6% vs 77.9%; p = .022). Refractory status (hazard ratio [HR] 1.98; 95% CI: 1.11-3.55) and MMC dose <0.4 mg/mL (HR 2.08; 95% CI 1.21-3.58) were significant risk factors for failure. Serious adverse events were more frequent in refractory eyes (7.6% vs 0.8%; p = .0097), as were reoperations (9.3% vs 1.7%; p = 0.019).

In SIBS microshunt implantation, refractory eyes demonstrated lower surgical success and higher rates of serious adverse events and reoperations compared with nonrefractory eyes.