Ab-Externo MicroShunt versus Trabeculectomy in Primary Open-Angle Glaucoma: Two-Year Results from a Randomized, Multicenter Study

Abstract

PurposeTo compare the effectiveness and safety of the MicroShunt (Santen Inc., Emeryville, CA, USA) versus trabeculectomy in patients with primary open-angle glaucoma (POAG). DesignProspective, randomized, multicenter trial conducted in the United States and Europe. ParticipantsAdult patients (aged 40-85 years) with mild to severe POAG inadequately controlled on maximum tolerated medical therapy and intraocular pressure (IOP) ≥15 mmHg and ≤40 mmHg. MethodsPatients were randomized 3:1 to standalone MicroShunt implantation (n=395) or trabeculectomy (n=132), both augmented with mitomycin C (MMC) 0.2 mg/mL for 2 minutes. Main Outcome MeasuresThe primary effectiveness endpoint was surgical success, defined as ≥20% reduction in mean diurnal IOP from baseline with no increase in glaucoma medications. Secondary endpoints included changes in mean IOP and medication use from baseline and the need for postoperative interventions. ResultsAt 2 years, the rate of surgical success was lower in the MicroShunt than in the trabeculectomy group (50.6% versus 64.4%, p=0.005). Mean diurnal IOP was reduced from 21.1 ± 4.9 mmHg at baseline to 13.9 ± 3.9 mmHg at 24 months in the MicroShunt group and from 21.1 ± 5.0 mmHg at baseline to 10.7 ± 3.7 mmHg at 24 months in the trabeculectomy group (p<0.001 compared with baseline in both groups). Mean medication use decreased from 3.1 to 0.9 in the MicroShunt group and from 2.9 to 0.4 in the trabeculectomy group (p<0.001 compared with baseline in both groups). Adverse events at 2 years were generally similar in the two groups, except that hypotony was more common in eyes undergoing trabeculectomy (51.1% versus 30.9%, p<0.001). Repositioning or explantation of the implant occurred in 6.8% of MicroShunt patients. The majority of these patients had device removal at the time of subsequent glaucoma surgery. Vision-threatening complications were uncommon in both groups. ConclusionAt 2 years, both the MicroShunt and trabeculectomy provided significant reductions in IOP and medication use, with trabeculectomy continuing to have greater surgical success.