Efficacy of the Ahmed S2 Glaucoma Valve Compared with the Baerveldt 250-mm2 Glaucoma Implant

ObjectiveTo compare the efficacy of the Ahmed S2 Glaucoma Valve with the Baerveldt 250-mm2 Glaucoma Implant in the treatment of adult glaucoma.DesignComparative case series.ParticipantsFifty-nine eyes of 59 patients who received the Ahmed S2 Glaucoma Valve and 133 eyes of 133 patients who received the Baerveldt 250-mm2 Glaucoma Implant by the Indiana University Glaucoma Service from 1996 to 2003.MethodsEyes that had previous drainage implant procedures were excluded from both groups. If both eyes of a single patient received an implant, the second eye to undergo implantation was excluded from the study.Main Outcome MeasuresKaplan–Meier survival with success defined as intraocular pressure (IOP) > 5 mmHg and < 22 mmHg and at least 20% reduction from preoperative IOP (with or without antiglaucoma medications) and without loss of light perception. Secondary outcome measures included intraocular pressure, visual acuity, number of glaucoma medications, and surgical complications.ResultsThe 2 groups were similar with regards to age, gender, race, neovascular glaucoma diagnosis, number of prior ocular surgeries, preoperative IOP, and number of preoperative glaucoma medications. Mean durations of follow-up were 20.0 months for Ahmed eyes and 22.9 months for Baerveldt eyes. Cumulative successes in the Ahmed group were 0.73 at 1 year and 0.62 at 2 years, whereas cumulative successes in the Baerveldt group were 0.92 at 1 year and 0.85 at 2 years (Kaplan–Meier survival functions: P = 0.03, log rank test). Male gender, African descent, neovascular glaucoma, and Ahmed implantation were found to be significant predictors of failure. At last follow-up visit, eyes in the Ahmed group had a significantly higher mean IOP (19.8±9.5 vs. 15.8±7.9 mmHg, P = 0.003, t test) and more antiglaucoma medications (1.4±1.2 vs. 0.9±1.1 medications, P = 0.008, Mann–Whitney test) than eyes in the Baerveldt group. Two methods for avoiding hypotony after Baerveldt 250-mm2 implantation had similar outcomes.ConclusionsOur study suggests that the Ahmed S2 Glaucoma Valve may be less effective at lowering IOP than the Baerveldt 250-mm2 Glaucoma Implant.