Long-Term Outcome of Second Ahmed Valves in Adult Glaucoma

Purpose To evaluate the long-term outcomes of second Ahmed glaucoma valve (AGV) implants in eyes with glaucoma. Design Retrospective interventional case series. Methods Patients with sequential second Ahmed valves implanted in the same eye from 1994 to 2016 were included. Success was defined with 3 criteria: (1) intraocular pressure (IOP) ≤ 21 mm Hg and IOP reduction of 20%; (2) IOP ≤ 18 mm Hg and IOP reduction of 25%; and (3) IOP ≤15 mm Hg and IOP reduction of 30%. The primary analysis was the 5-year Kaplan-Meier survival rate for each criterion. Failure was established when the success criterion was not met at 2 consecutive visits at least 3 months after the surgery. Loss of light perception, requirement for additional glaucoma surgery, hypotony maculopathy, and serious complications were also considered failures. Results One hundred ten eyes from 104 patients were included with a mean follow-up of 5.0 years (interquartile range [IQR] 1.6–7.33 years). The median (IQR) age at the second AGV was 68.0 (53.5–77.9) years. The median (IQR) time between surgeries was 2.1 (0.7–4.0) years. The 5-year Kaplan-Meier survival rates were 57%, 51%, and 30% for criteria 1, 2, and 3, respectively. Conclusion A second AGV is effective in reducing IOP in patients who require additional IOP lowering after a first AGV. The success rates are comparable to primary AGV implantation, and to trabeculectomy in eyes with a previously implanted glaucoma drainage device. A second AGV is a viable option in eyes with inadequate IOP levels after a primary AGV.