Abstract and Introduction
Purpose: To evaluate the surgical outcomes of the implantation of an additional Ahmed glaucoma valve (AGV) into the eyes of patients with refractory glaucoma following previous AGV implantation.
Methods: This study is a retrospective review of the clinical histories of 23 patients who had undergone a second AGV implantation after a failed initial implantation. Age, sex, prior surgery, glaucoma type, number of medications, intraocular pressure (IOP), visual acuity, and surgical complications were analyzed. Surgical success was defined as IOP maintained below 21 mm Hg, with at least a 20% overall reduction in IOP, regardless of the use of IOP-lowering medications.
Results: Following the implantation of a second AGV, the mean IOP decreased from 39.3 to 18.5 mm Hg (52.9% reduction, P<0.001). The mean number of postoperative IOP-lowering medications administered decreased from 2.8 to 1.7 after the second AGV implantation (P<0.001). The cumulative probability of success for the procedure was 87% after 1 year and 52% after 3 years. Three patients (13.0%) experienced bullous keratopathy after the second AGV implantation. None of the patients showed any evidence of diplopia or ocular movement limitation as a result of the presence of 2 AGVs in the same eye. Prior trabeculectomy was found to be a significant risk factor for failure (P=0.027).
Conclusions: A second AGV implantation can be a good choice of surgical treatment when the first AGV has failed to control IOP.
The Ahmed glaucoma valve (AGV; New World Medical, CA) is a glaucoma drainage device (GDD), which is used for the treatment of refractory glaucoma, either as a primary surgical intervention or following the failure of conventional filtration surgery.[1–6] In cases where intraocular pressure (IOP) remains high after AGV implantation, additional procedures are required, such as repair of the first operation site, the implantation of a second AGV, or the use of cyclodestructive procedures. The repair procedure is technically challenging because of the risk of excessive bleeding and scar tissue formation. Cyclodestructive procedures are associated with a risk of uveitis, vision loss, hypotony, and phthisis.[8,9] AGV implantation tends to be associated with a fairly high rate of successful outcomes, leading many surgeons to favor a second AGV implantation to achieve IOP control. To date, there have been few reports in the literature examining the surgical outcomes of a second AGV implantation in patients with a preexisting AGV.[7,10–13]
Among various AGV models, 2 types of AGVs with different surface areas are commonly used: FP7 (184 mm2) and FP8 (96 mm2). Our previous study suggested that the surgical outcomes were similar with both FP8 AGV and FP7 AGV implantation, with respect to vision preservation, IOP reduction, and the number of required glaucoma medication. This finding suggests that implantation of FP8 AGV as a second GDD would be helpful for refractory glaucoma. To the best of our knowledge, no study has reported surgical outcome regarding this issue. This study was designed to investigate the safety and efficacy of implanting a second AGV by using both FP7 and FP8 models in patients with refractory glaucoma.
J Glaucoma. 2016;25(6):e620-e624. © 2016 Lippincott Williams & Wilkins