Abstract
Purpose :
There is a lack of information regarding the efficacy and function of Ahmed Glaucoma Valves (AGV) that do not exhibit a distinct fluid stream priming pattern. The purpose of this study is to determine if there is a significant difference in valve function by comparing the steady state pressure across valves with or without a stream priming pattern.
Methods :
In this experimental study, 50 AGVs were primed in standard fashion under microscope visualization by injecting balanced salt solution through a 27-gauge cannula and the priming pattern was recorded. Of these, a total of 15 AGVs were further tested using similar numbers of AGVs with or without a distinct stream priming pattern. A perfusion system consisting of a syringe pump, pressure transducer, water bath and test sample connected in sequence via tubing was used to determine the steady state pressure across the valves. All AGV’s achieved steady state pressure by 60 seconds of perfusion. A student t-test was used to assess statistically significant differences in the mean steady state pressures between the two groups of AGV’s.
Results :
Of the 50 AGVs tested, 43 (86%) demonstrated a distinct jet/stream priming pattern, with only 7 (14%) having a pooling pattern without a distinct fluid stream. The perfusion study included 15 AGV’s; 8 with and 7 without a distinct stream priming pattern. Steady state pressure was reached by 45 seconds for all samples. The steady state pressure across the AGVs was similar between the two priming groups at all times tested. The mean steady state pressure (± standard deviation) in the stream group at 60 seconds was 11.00 ± 1.90 mmHg and 10.31 ± 2.53 mmHg in the group without a distinct stream pattern (p=0.56).
Conclusions :
The predominant fluid pattern noted during priming of the Ahmed Glaucoma Valve is a distinct stream exiting the valve, with approximately 1 in 7 not demonstrating this pattern. However, we found that the fluid pattern visualized during priming has no predictive value on the functionality of the valve with similar steady state pressures achieved regardless of priming pattern.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.