Trabeculectomy After Ahmed Glaucoma Valve Implantation Versus Repeat Trabeculectomy.

PURPOSE: To compare outcomes of trabeculectomy (TRAB) performed after Ahmed glaucoma valve (AGV) implantation with those of repeat TRAB and to identify factors related to surgical failure. METHODS: In this retrospective study, patients who underwent a second TRAB were divided into two groups: TRAB after AGV implantation (TaA) and repeat TRAB (TaT). Primary outcome was surgical success, defined as a postoperative intraocular pressure (IOP) <21 mmHg or a ≥20% reduction from baseline, with or without glaucoma medications. Pre- and postoperative IOP and IOP reduction rates were compared via paired sample t-tests. Surgical success rates were analyzed with Kaplan-Meier survival analysis. Risk factors for surgical failure were evaluated with Cox proportional hazards model. RESULTS: Forty-three eyes were included (TaA, n=20; TaT, n=23), and the TaA group had more secondary glaucoma (P=0.004) and higher baseline IOP (P <0.001). Postoperative IOP, IOP reduction rates, and success rates were comparable between the two groups up to 2 years. Higher postoperative IOP at 1 month was associated with failure in both groups (hazard ratio [HR] 1.151, P=0.036 in TaA; HR 1.188, P=0.009 in TaT). The postoperative 1-month IOP ≥17.5 mmHg was associated with an increased risk of failure. CONCLUSIONS: TRAB after AGV implantation achieved similar postoperative outcomes to those of repeat TRAB, supporting its role as a potential secondary option in intractable glaucoma treatment. Early postoperative IOP is a favorable prognostic marker, highlighting the importance of stabilizing IOP during this period. PRCIS: Trabeculectomy after Ahmed valve implantation showed outcomes comparable to repeat trabeculectomy, with prior shunt surgery not precluding success. Early postoperative intraocular pressure at 1 month was a strong predictor of long-term surgical success.