Clinical Outcomes of Ahmed Glaucoma Valve in Posterior Segment Versus Anterior Chamber

Abstract

To compare the intermediate-term intraocular pressure (IOP) control and complication profile of the Ahmed Glaucoma Valve (AGV) implanted posteriorly through the pars plana in eyes undergoing concurrent pars plana vitrectomy (PPV) with device implantation in the anterior chamber (AC) in nonvitrectomized eyes. : We retrospectively reviewed the medical records of 31 case eyes (30 patients) with refractory glaucoma that underwent posterior implantation of AGV after complete PPV and compared them to 31 control eyes (31 patients) with refractory glaucoma that underwent implantation of AGV in the AC. Case-control patients were matched one-to-one on the basis of principal glaucoma diagnosis. All surgeries were performed at 1 institution using a silicone-plate device. Success was defined as intraocular pressure (IOP)≥ 5 mm Hg and ≤ 21 mm Hg with or without glaucoma medications at final follow-up, no additional glaucoma surgery, no removal of the implant, and no loss of light perception. The average follow-up was 20.9 months (range, 6 to 54 mo) for the posterior group and 20.5 months (range, 4 to 48 mo) for the anterior group. The reduction in IOP was similar in both groups at all postoperative time points. The number of postoperative glaucoma medications in both groups was not statistically different at final follow-up. Success rates at final follow-up were identical, 83.9% in both groups, and Kaplan-Meier survival curve analysis showed no significant difference between the 2 groups (P=0.96). Postoperative complications were similar between the 2 groups, except there were more instances of early postoperative flat AC in the anterior group than the posterior group (P=0.01). The AGV can similarly control IOP in the majority of cases, whether the tube is placed in the posterior segment after PPV or in the AC of nonvitrectomized eyes.