Mitomycin C 0.2 mg/ml versus Mitomycin C 0.4 mg/ml during the Implantation of an Ab Externo Polystyrene-isobutylene-styrene Microshunt: A Mega-analysis

Abstract

Purpose: To compare the effectiveness and adverse event profile of standalone polystyrene-isobutylene-styrene (SIBS) microshunt implantation with adjunct mitomycin C (MMC) 0.2 mg/ml and MMC 0.4 mg/ml.

Design: Mega-analysis using individual patient data from international prospective and retrospective clinical studies.

Participants: Patients with glaucoma who underwent implantation of a SIBS microshunt with MMC as a standalone procedure.

Methods: A comparison of eyes that received MMC 0.2 mg/ml or 0.4 mg/ml.

Main outcomes measures: Primary outcome was complete success defined as the proportion of eyes at 1 year with all of the following: (1) no 2 consecutive intraocular pressures (IOPs) > 17 mmHg; (2) no clinical hypotony; (3) ≥ 20% IOP reduction from baseline; and (4) no use of glaucoma medications. Secondary outcomes included IOP thresholds of 12 mmHg, 14 mm Hg, and 21 mmHg, median IOP, number of medications, risk factors for failure, interventions, adverse events, and reoperations.

Results: At 1 year, the complete success rate was significantly higher (71.3% vs. 50.46%; P < 0.001) and the median IOP was significantly lower (13.0 vs 14.2 mmHg; P < 0.05) in the MMC 0.4 mg/ml group. Mitomycin C 0.2 mg/ml was found to be a significant risk factor for failure (hazard ratio 1.75; 95% confidence interval 1.14-2.67). Needling and surgical revision occurred at a lower rate in the MMC 0.4 mg/ml group (7% vs 18.8%; P = 0.002 and 4.3% vs 13.7% P = 0.0087, respectively). Adverse events occurred at a similar frequency in both groups (26.6% MMC 0.2 mg/ml vs 29.6% MMC 0.4 mg/ml; P = 0.46), most of which were early and transient.

Conclusion: Polystyrene-isobutylene-styrene microshunt implantation with MMC 0.4 mg/ml resulted in a higher success rate with greater IOP reduction compared with MMC 0.2 mg/ml. Higher MMC concentration was not associated with increased serious adverse events.

Financial disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Keywords: Microinvasive bleb surgery; Microshunt; Mitomycin C; SIBS.