Pooled Analysis of Three MicroShunt Studies in Primary Open-Angle Glaucoma Evaluating Different Concentrations of Applied Mitomycin C

Abstract

Introduction: The PRESERFLO MicroShunt is an 8.5-mm-long (70-µm lumen) controlled ab externo filtration surgery device made from poly[styrene-block-isobutylene-block-styrene] (SIBS). Three prospective, open-label clinical trials (ClinicalTrials.gov Identifiers: NCT00772330; NCT01563237; NCT02177123) evaluated the 2-year effectiveness and safety of MicroShunt implantation plus mitomycin C (MMC). This pooled analysis compared outcomes in patients receiving 0.2 or 0.4 mg/ml MMC during MicroShunt implantation.

Methods: Patients aged 18-85 years with primary open-angle glaucoma (intraocular pressure [IOP] 18-35 mmHg) uncontrolled on maximal tolerated medical therapy and/or where glaucoma progression warranted surgery who underwent MicroShunt implantation with/without cataract surgery, and with adjunctive use of 0.2 or 0.4 mg/ml MMC. Two-year outcomes included changes in IOP and glaucoma medications, complete success rates (IOP ≥ 6 to < 14 mmHg or ≥ 20% reduction, without medications), and rates of procedure/device-related adverse events (AEs) and serious AEs (SAEs).

Results: Of the 125 included patients, 58 received 0.2 mg/ml MMC and 67 received 0.4 mg/ml MMC). Mean percent reduction in IOP was significantly greater in patients receiving 0.4 than 0.2 mg/ml MMC (- 40.9% vs. - 34.5%, P < 0.05). Mean glaucoma medication use was reduced to a lower level between baseline and year 2 in the 0.4 than in the 0.2 mg/ml MMC group. At year 2, the percentage of medication-free patients (85.2% vs. 58.0%, P < 0.01) and the complete success rates (71.6% vs. 48.3%, P < 0.01) were significantly higher in the 0.4 than in the 0.2 mg/ml MMC group. Rates of procedure/device-related AEs and SAEs did not differ significantly in the two groups (P > 0.05).

Conclusions: IOP and glaucoma medication use at year 2 were lower, and complete success rate was higher, in patients administered 0.4 mg/ml than 0.2 mg/ml MMC. Although there is no consensus on the optimal concentration of MMC, these findings may guide surgeons until further evidence from controlled trials becomes available.

Keywords: Antifibrotic agents; Glaucoma filtration surgery; MMC; MicroShunt; Primary open-angle glaucoma; SIBS.

Fig. 1

Patient disposition

Fig. 2

Determination of intraocular pressure over time in patients administered 0.2 and 0.4 mg/ml MMC. A Mean IOP from baseline to year 2. B Mean and median IOP over 2 years of follow-up (per-protocol population). IOP intraocular pressure, MMC mitomycin C

Fig. 3

Kaplan–Meier analysis of the overall probabilities of success, defined as an IOP ≥ 6 and < 14 mmHg, in patients treated with 0.2 and 0.4 mg/ml MMC from baseline to year 2 in the per-protocol population. IOP intraocular pressure, MMC mitomycin C

Fig. 4

A Mean and median numbers of glaucoma medications per patient over 2 years of follow-up. B Percentage of patients who were medication-free over 2 years of follow-up (per-protocol population)