Risk Factors for Failure in Glaucoma Patients Undergoing Microshunt Implantation

PURPOSE: To evaluate risk factors for failure of Microshunt in glaucoma patients. DESIGN: Multicenter retrospective cohort study. METHODS: The study included 220 eyes from 220 consecutive glaucoma patients undergoing Microshunt implantation at six glaucoma units. Four intraocular pressure (IOP) success criteria were defined: (A) IOP ≤21 mm Hg with ≥20% IOP reduction; (B) IOP ≤18 mm Hg with ≥20% IOP reduction; (C) IOP ≤15 mm Hg with ≥25% IOP reduction; and (D) IOP ≤12 mm Hg with ≥30% IOP reduction from baseline. Kaplan–Meier analysis was used to estimate success rates according to the criteria above, and multivariable Cox models were used to identified risk factors for failure according to criterion A. RESULTS: Success rates varied based on different criteria, ranging from 43.3% to 62.5% (overall success for criteria D and A, respectively) and from 35.3% to 44.4% (complete success for criteria D and A, respectively) at 1-year follow-up. Higher intraoperative MMC concentration was associated with reduced risk of failure to maintain complete (0.4 vs 0.2 mg/mL: hazard ratio [HR] = 0.441, P < .001) and overall (0.4 vs 0.2 mg/mL: HR = 0.360, P = .004) success. For complete success, other risk factors for failure were pseudoexfoliation glaucoma/pigmentary glaucoma (HR = 1.641, P = .004), primary angle closure glaucoma (HR = 1.611, P < .001), and previous non-glaucomatous ocular surgeries (HR = 2.301, P = .002). For overall success, other risk factors for failure were lower preoperative IOP (for 1-mm Hg increase, HR = 0.934, P = .005), higher number of preoperative antiglaucoma agents (HR = 1.626, P < .001), and Microshunt combined with cataract surgery (HR = 1.526, P = .033). CONCLUSIONS: This study identified risk factors for Microshunt failure, highlighting the importance of high intraoperative MMC dose and careful patient selection to optimize surgical success.