Surgical Outcomes of Superior Versus Inferior Glaucoma Drainage Device Implantation

Abstract

To compare the safety and intraocular pressure (IOP) lowering efficacy of initial glaucoma drainage device (GDD) implantation performed at the superior versus inferior limbus. 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, χ test, and Kaplan-Meier time to failure analysis. 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). 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.