Ahmed Valve Implantation for Refractory Glaucoma following Pars Plana Vitrectomy

PURPOSE: To evaluate the effectiveness of Ahmed valve implantation for refractory glaucoma following pars plana vitrectomy. METHODS: Seventeen eyes of 15 patients suffering from secondary glaucoma following pars plana vitrectomy underwent Ahmed valve implantation. All the eyes were in critical condition, and intraocular pressure could not be controlled with anti-glaucoma medications. Success was characterized by an intraocular pressure less than 22 mmHg and greater than 6 mmHg, regardless of anti-glaucoma medication usage. RESULTS: The total success rate was 83.4% at 6 months and 76.4% at the final visit. The reduction in intraocular pressure and the number of medications used postoperatively were both statistically and clinically significant (p<0.005). Postoperative complications included: transiently increased intraocular pressure, transient hyphema, early postoperative hypotony, choroidal detachment, malposition of the valve tip, and phthisis bulbus. CONCLUSIONS: Ahmed valve implantation is a safe and effective method for refractory glaucoma following vitrectomy.