Trabeculectomy After Ahmed Glaucoma Valve Implantation Versus Repeat Trabeculectomy

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.

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.

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.

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.

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.