Surgical Outcomes of Superior Versus Inferior Glaucoma Drainage Device Implantation

Purpose: To compare the safety and intraocular pressure (IOP) lowering efficacy of initial glaucoma drainage device (GDD) implantation performed at the superior versus inferior limbus. Methods: A retrospective chart review was conducted to identify patients with glaucoma who had undergone initial Baerveldt GDD surgery at the inferior limbus for uncontrolled IOP. All eyes of patients had a minimum of 6 months of postoperative follow-up. These eyes were frequency-matched to eyes with initial Baerveldt GDD implantation performed at the superior limbus, within 5 years of age and 6 months of follow-up. Baseline demographic and clinical information, as well as preoperative and postoperative IOP, visual acuity, and number of antiglaucoma medications were extracted. Failure was defined as IOP > 21 mm Hg or not reduced by 20% below baseline on 2 consecutive follow-up visits after 3 months, IOP <= 5 mm Hg on 2 consecutive follow-up visits after 3 months, reoperation for glaucoma, or loss of light perception vision. Statistical methods consisted of Student t tests, chi(2) test, and Kaplan-Meier time to failure analysis. Results: Fifty eyes (17 inferior, 33 superior) of 43 patients were enrolled. Mean postoperative follow-up in both groups were similar (mean 26.2 +/- 15.2 mo for inferior and 23.9 +/- 10.43 mo for superior, P = 0.54). Trabeculectomy had been performed previously in 8/17 (47%) and 11/33 (33%) eyes (P = 0.34) with inferior and superior implants, respectively. Mean preoperative IOP (mm Hg) in the superior group (26 +/- 11) was significantly higher (P = 0.02) when compared with the inferior group (21 +/- 7). Success rates were similar (P > 0.05) between the inferior and superior GDD groups during the study period, with 64.7% and 75.8% classified as successful at 1-year of follow-up and 43.1% and 65.7% at 2 years of follow-up, respectively. There was no difference in cumulative proportions of eyes failing between the groups (P = 0.20, log-rank test). The mean postoperative IOP and number of antiglaucoma medications were similar (all P > 0.05) in both groups during the first 2 years of postoperative follow-up. The frequency and types of postoperative complications in both the groups were similar. The 36-month cumulative reoperation rates for IOP control were 33.8% and 9.1%, respectively, in the inferior and superior GDD groups (P = 0.04 log-rank test). Conclusions: No differences were observed in the overall success rates of initial GDD implantation performed at the superior and inferior limbus in this cohort. However, inferior GDD implantation was associated with a greater incidence of reoperation for IOP control.