Intermediate Outcomes of SIBS Microshunt, Gelatin Microstent and Trabeculectomy: A Comparative Retrospective Cohort Study

PURPOSE: To compare the two-year surgical success rates, the complications and risk factors for failure of the SIBS microshunt, the gelatin microstent and trabeculectomy. DESIGN: Single-center, single-surgeon retrospective cohort study. SUBJECTS: 142 eyes from 124 adult patients diagnosed with glaucoma (43 SIBS microshunt, 63 gelatin microstent and 36 trabeculectomy). METHODS: Consecutive eyes that underwent SIBS microshunt implantation, gelatin microstent implantation and trabeculectomy were compared. OUTCOME MEASURES: The primary outcome was the proportion of eyes achieving surgical success at 2 years, defined as 1)intraocular pressure (IOP) between 6-17mmHg (inclusive) without meds (complete success), or with meds (qualified success), 2)No IOP readings >17mmHg or <6mmHg with clinical hypotony, on two consecutive visits, 3)No surgical revision, reoperation or loss of light perception. Secondary outcomes included success rates for IOP range of 6-14 and 6-21mmHg, postoperative IOP, meds, complications, additional interventions and risk factors for failure. RESULTS: SIBS microshunt group included a significantly higher proportion of eyes with prior failed glaucoma filtering surgery (41.9% vs 0% for gelatin microstent and 2.8% for trabeculectomy, respectively; p<0.001). At 24 months, complete success rates in the 6-17mmHg range were 72.1% for SIBS microshunt, compared with 50.0% for trabeculectomy (p=0.034) and 38.1% for gelatin microstent (p<0.0001). Qualified success was achieved in 83.7%, 66.7%, and 55.6%, respectively, with SIBS demonstrating superior outcomes than gelatin microstent (p=0.003). In the multivariable analysis, the gelatin microstent (HR 3.43; 95%CI 1.61-7.31), and combined cataract surgery (HR 2.06; 95%CI 1.27-3.35) were associated with increased hazard of failure, while age ≥70 years was associated with lower risk of failure (0.54; 95%CI 0.30-0.98). All procedures significantly reduced IOP and meds (p<0.001). Complication rates were similar across groups, most resolving before 3 months. Needling was performed in 2.3% (SIBS microshunt), 30.2% (gelatin microstent), and 30.6% (trabeculectomy) of eyes, and 5-FU injections in 48.8%, 25.4%, and 50.0%, respectively. Revision rates were 4.7%, 8.5%, and 0%, respectively (p=0.283), while reoperations were higher with gelatin microstent (15.9% vs 2.3% and 2.8%; p=0.022). CONCLUSIONS: Despite higher-risk baseline profile, the SIBS microshunt achieved higher 2-year success rates than trabeculectomy and gelatin microstent across multiple IOP ranges, with comparable complications and fewer reoperations.