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Article Abstract
Purpose: To investigate the mechanism of action and consistency in flow characteristics of the Ahmed glaucoma valve (AGV) under simulated physiological conditions in-vitro and to evaluate whether resistance during priming has any effect on performance of the device.
Methods: Each newly opened AGV device was connected to a digital manometer and was primed with normal saline. The device was then placed in a saline bath and connected to an open manometer, a digital manometer, and an infusion pump. Saline was infused at a rate of 3 μL/min for 24 hours. Digital manometer readings were recorded at 4 Hz.
Results: Data obtained from 9 devices are presented as medians (ranges). The priming pressure was 1130 (835, 1625) mm Hg. Pressure versus time curves showed two distinct phases; transient and steady phases. The transient phase peak pressure was 24 (13, 45) mm Hg. In the steady phase, opening and closing pressures were 13 (10, 17) and 7 (4, 9) mm Hg, respectively; the valve leaflets briefly opened every 73.9 (51, 76.6) minutes and the fluctuation of pressure (difference between opening and closing pressures) was 6 (3, 9) mm Hg. The Spearman correlation coefficient between priming and opening and priming and closing pressure was ρ = -0.13 ( = 0.72) and ρ = -0.36 ( = 0.33), respectively.
Conclusions: The device showed functionality like a valve. The resistance during priming did not affect opening and closing pressures of the AGV. This study showed variable in vitro performance of the AGV.
Translational Relevance: These laboratory findings might, at least partly, explain the variability in the clinical outcome of the device.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6016431 | PMC |
| http://dx.doi.org/10.1167/tvst.7.3.19 | DOI Listing |
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