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.
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