Modified Ahmed glaucoma valve implantation in the treatment of refractory glaucoma

Abstract

Objective To explore the efficacy of a modified technique with Ahmed glaucoma valve (AGV) implantation in the treatment of refractory glaucoma. Methods This retrospective study included a total of 47 eyes of 46 refractory glaucoma patients who underwent a modified Ahmed glaucoma valve implantation in Wuhan Aier Hospital from January 2011 to December 2013. The sutureless AGV implantation technique was as follows: The drainage plate was secured between the episclera and Tenon's capsule with no suture placement. An approximate 6 mm radical scleral tunnel was made from 5 mm to the limbus and near the limbus respectively, and the drainage tube was inserted through the tunnel, followed by a sclerotomy at the limbus through which the tube was introduced into the anterior chamber. The extraocular portion of the tube was covered. Best corrected visual acuity (BCVA) , intraocular pressure (IOP) and the number of anti-glaucoma medications before and after the surgery and postoperative complications were evaluated. Patients were followed up and postoperative data was obtained at 1 week, 1 month, 6 months, and then at 6-month intervals after surgery. Comparsions of IOP at different time points after surgery were performed by using repeat mesured ANOVA; while a paired nonparametric rank sum test was used to compare the number of glaucoma medications, and visual acuity preoperatively and postoperatively or at the last follow-up. Results Visual acuity was not significantly different between pre-operation and the final follow-up (Z=1.826, P>0.05). Preoperative IOP varied from 15 to 69 mmHg, and IOP was between 9 and 23 mmHg at the final follow-up. The mean IOP was significantly reduced from a preoperative 43.26±8.14 mmHg to a postoperative 15.3±5.9 mmHg (F=12.16, P<0.05). The number of anti-glaucoma medications was significantly reduced from 4 at preoperation to 1 postoperatively (Z=7.32, P<0.05). At the last visit, the complete success rate of the AVG implantation reached 72.3%, and the conditional success rate hit 87.2%. Postoperative complications included anterior chamber hemorrhage, obstruction of the drainage tube, a shallow anterior chamber and encapsulated cystic blebs around the plate, which could all be controlled with additional treatments. Conclusion The modified Ahmed glaucoma valve implantation is confirmed as an effective way to treat refractory glaucoma, and it is worth being used routinely in the clinic because it is a less complicated procedure, reduces surgery time and has fewer postoperative complications. Key words: Ahmed glaucoma valve implantation; Modified technique; Refractory glaucoma; Surgical treatment