Comparison of Repeat Trabeculectomy Versus Ahmed Valve Implantation After Initial Failed Trabeculectomy Surgery

PRÉCIS: Repeat trabeculectomy is associated with similar postoperative intraocular pressure (IOP), a lower complication rate, and a lower need for medications when compared with Ahmed valve implantation (AVI) when performed after initially failed trabeculectomy. OBJECTIVE: The goal of this study was to compare the efficacy of repeat trabeculectomies and AVI after an initial failed trabeculectomy. METHODS: All studies that investigated the postoperative success of patients who underwent AVI or repeat trabeculectomy with mitomycin- C after a prior failed trabeculectomy with mitomycin- C found in PubMed, Cochrane Library, Scopus, and CINAHL were included. Mean preoperative and postoperative IOP, proportions of complete and qualified successes, and proportions of complications were extracted from each study. Meta-analyses were performed to compare the differences between the two surgical approaches. Methods of measuring complete and qualified success were too heterogeneous among the included studies to allow for meta-analysis. RESULTS: The literature search yielded 1305 studies, and 14 studies were included in the final analysis. Mean IOP was not significantly different between the two groups preoperatively and then after 1, 2, and 3 years. Mean number of medications between the two groups was similar preoperatively. After 1 and 2 years, the mean amount of glaucoma medications in the AVI group was approximately twice that of the trabeculectomy group; however, this relationship was only significant at 1 year of follow-up ( P = 0.042). In addition, the cumulative proportion of overall and sight-threatening complications was significantly higher in the AVI group. CONCLUSION: Repeat trabeculectomy with mitomycin- C and AVI may both be considered after failed primary trabeculectomy. However, our analysis suggests that repeat trabeculectomy may be the preferred method as it provides similar efficacy with fewer disadvantages.