Ahmed glaucoma valves in refractory glaucoma: a 7-year audit.

PURPOSE To present the long-term results of Ahmed glaucoma valve (AGV) implantation. METHODS Consecutive case series of 94 eyes with AGV implantation over 7 years. Temporary tube ligation with C3F8 gas fill was used in high-risk eyes (group G&L) and compared with standard implantation in both phakic (group A) and pseudophakic/aphakic eyes (group B). Success was intraocular pressure (IOP) of 6 mm Hg or greater and 21 mm Hg or less and/or IOP reduction of 20% or greater. RESULTS Average follow-up was 28.9+/-20.3 months. The mean preoperative IOP changed from 30.8+/-8.2 to 19.7+/-7.6 mm Hg and mean preoperative medications changed from 3.3+/-1.2 to 1.2+/-1.1 at the final visit. Cumulative probability of survival at 1 and 4 years was 89.1% and 72.9%. There was no statistically significant difference in success between the three groups, but complications due to postoperative hypotony (six eyes) only occurred in group B. Other complications were corneal decompensation (three eyes), tube erosion (six eyes) and aqueous misdirection (four eyes). CONCLUSIONS AGV implantation offered good long-term IOP control with a success rate of 78.7%. The authors recommend C3F8 gas fill and temporary tube ligation in eyes at high risk of postoperative hypotony and the use of donor sclera or human pericardial patch to prevent tube erosion.