Clinical Ophthalmology (Apr 2025)
Functionality and Priming Stream Patterns of the Ahmed Glaucoma Valve in a Laboratory Setting
Abstract
Iden M Amiri, Heran W Gebreyesus, Jennifer L Patnaik, Malik Y Kahook, Leonard K Seibold Department of Ophthalmology, University of Colorado School of Medicine, Aurora, CO, USACorrespondence: Leonard K Seibold, University of Colorado School of Medicine, Department of Ophthalmology, 1675 Aurora Court, Aurora, CO, 80045, USA, Tel +1 7208482500, Fax +1 7208485014, Email [email protected]: To determine if there is a significant association between the steady state pressure of Ahmed Glaucoma Valves (AGVs) and the fluid pattern exhibited during the priming step of implantation.Methods: In this experimental laboratory study, fifty AGVs were primed according to manufacturer guidelines by injecting balanced salt solution through a 27-gauge cannula. Group 1 consisted of 8 AGVs with a distinct stream priming pattern. Group 2 consisted of 7 AGVs without a distinct stream priming pattern (pooling). These valves were further tested using a perfusion system to measure steady-state pressure across the valve. A Student’s t-test was used to assess the differences in mean steady-state pressures.Results: 43/50 AGVs (86%) demonstrated a distinct stream of fluid during priming (group 1), while 7 (14%) showed a pooling of fluid only, without a focal stream (group 2). Steady-state pressure was achieved by 45 seconds for the 15 samples. The mean steady-state pressure (± standard deviation) at 60 seconds was 11.00 ± 1.90 mmHg for group 1 and 10.31 ± 2.53 mmHg for group 2 (p = 0.56), demonstrating no significant difference between groups.Conclusion: The most common fluid pattern observed is a focal stream of fluid exiting the valve, with a minority exhibiting a slow pooling of fluid. The fluid pattern observed during AGV priming does not predict the valve’s functionality, as both priming patterns resulted in similar steady-state pressures, which were consistently in line with manufacturer specifications.Plain Language Summary: Glaucoma is a leading cause of irreversible blindness, and devices like the Ahmed Glaucoma Valve (AGV) are often used in surgery to control elevated eye pressure. Before implanting the AGV, surgeons flush the valve with a fluid (a process called “priming”) to ensure it works correctly. However, the fluid pattern during priming—either a distinct jet or a slower pooling—has caused debate. Some surgeons believe a pooling pattern might indicate a faulty valve and may discard it, leading to waste and longer surgeries.This study tested 50 AGVs in a lab to see if the priming pattern affects how well the valve controls pressure. Most valves (86%) showed a jet pattern, while a few (14%) had a pooling pattern. After further testing, we found no difference in how the valves performed, regardless of the priming pattern. Both types regulated pressure effectively, meeting the manufacturer’s standards.These results suggest that the priming pattern does not predict valve functionality. Discarding valves based on the priming pattern may not be necessary and could increase waste and costs. Future research is needed to confirm these findings in actual surgical settings and understand why priming patterns vary.Keywords: Ahmed Glaucoma Valve, AGV, priming, intraocular pressure, glaucoma drainage device
