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

Background: To compare the outcomes of combined viscocanalostomy (VCO) and repeat trabeculotomy (retbo) versus retbo alone in primary congenital glaucoma (PCG) with prior failed trabeculotomy. Methods: This prospective study enrolled 164 PCG eyes with insufficient response to initial angle surgery, equally divided into VCO+retbo and retbo groups (n=82 each). Success was defined as intraocular pressure (IOP) between 6–21 mmHg with ≥20% reduction from baseline, classified as 'complete' (no medications) or 'qualified' (with medications). Results: Mean follow-up was 30.36±13.38 months. In successful eyes, IOP decreased from 28.52±6.06 to 16.2±2.94 mmHg in VCO+retbo and from 27.35±5.29 to 17.67±4.35 mmHg in retbo; medication use changed from 2.70±0.78 to 2.04±1.03 and 2.69±0.97 to 0.98±1.10, respectively (all p<0.001). Final IOP did not differ between groups, but retbo required fewer medications (p<0.001). Failure rates were 31.7% (VCO+retbo) and 37.8% (retbo) (p=0.219). Complete success was achieved in 9.8% (VCO+retbo) versus 32.9% (retbo), while qualified success was 58.5% versus 29.3% (p<0.001). IOP >30 mmHg before second surgery predicted higher failure risk (HR=2.33, 95% CI: 1.33–4.11, p=0.003). Conclusions: Adding VCO to retbo in PCG with prior failed trabeculotomy offers no additional benefit over retbo alone. Trial registration: 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