Combined viscocanalostomy and retrabeculotomy versus retrabeculotomy for management of refractory primary congenital glaucoma: a comparative study.

backgroundTo evaluate and compare the long-term clinical outcomes of combined viscocanalostomy and repeat trabeculotomy (VCO+retbo) versus repeat trabeculotomy alone (retbo) in eyes with primary congenital glaucoma (PCG) that failed initial angle surgery.

methodsThis prospective comparative study evaluated 164 eyes with PCG that exhibited an insufficient response to primary trabeculotomy, divided into VCO+retbo (n = 82) and retbo (n = 82) groups. Treatment success was defined as an intraocular pressure (IOP) between 6 and 21 mmHg with a ≥ 20% reduction from baseline, categorized as complete (medication-free) or qualified (with medications). Overall treatment failure served as the principal comparative outcome, whereas complete/qualified success rates and final medication burden were designated as secondary exploratory endpoints.

resultsThe mean follow-up duration was 30.36 ± 13.38 months. Regarding the principal outcome, overall failure rates did not differ significantly between groups (31.7% for VCO+retbo vs. 37.8% for retbo; p = 0.219), nor did Kaplan-Meier cumulative survival (log-rank p = 0.290). In multivariable Cox regression, baseline IOP > 30 mmHg prior to second surgery was the sole independent predictor of failure (HR = 2.33, 95% CI: 1.33-4.11, p = 0.003), whereas surgical technique was not predictive. For secondary outcomes among successfully controlled eyes, final IOP did not differ significantly between groups (16.20 ± 2.94 mmHg vs. 17.67 ± 4.35 mmHg). However, the retbo group maintained control with significantly fewer topical medications (0.98 ± 1.10 vs. 2.04 ± 1.03, p < 0.001). Complete success was achieved in 32.9% of retbo eyes compared to 9.8% of VCO+retbo eyes, whereas qualified success was 29.3% versus 58.5%, respectively (p < 0.001).

conclusionsNo statistically significant difference in overall treatment failure was detected between VCO+retbo and retbo in refractory PCG. Repeat trabeculotomy alone was associated with a higher rate of medication-free success and lower medication burden; these secondary exploratory findings require confirmation in prospective randomized trials with standardized prescribing protocols. ETHICS APPROVAL: The study was approved by the local ethics committee of Tehran University of Medical Sciences (IR. TUMS. FARABIH. REC. 1402.009). The online version of the decree is publicly available at: https://ethics. RESEARCH: ac.ir/IR.TUMS.FARABIH.REC.1402.009 Trial registration: This study was not registered in a clinical trial registry. Per our institution's standard practice, prospective registration is reserved for randomized controlled trials; as both surgical techniques compared here are routine, established procedures rather than novel or experimental interventions, the study proceeded under institutional ethics approval alone. CLINICAL TRIAL NUMBER: Not applicable.