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Abstract #91700 Published in IGR 21-4

Conversion of Flow-restrictive Ahmed Glaucoma Valve to a Nonrestrictive Drainage Implant by Slicing the Valve Leaflets: An In Vitro Study

Senthil S; Kumar GM; Sri Harsha Chittajallu SN; Choudhari NS; Garudadri C; Richhariya A
Journal of Glaucoma 2021; 30: 5-9


PRECIS: With a newly designed blade, slicing of the Ahmed glaucoma valve (AGV) leaflets helped to convert the flow-restrictive AGV into a non-flow-restrictive device. Flow characteristics by our in-vitro study confirmed the loss of resistance of AGV valve leaflets. PURPOSE: To describe a new blade to destroy the valve leaflets of AGV and to report the in-vitro flow characteristics of AGV after valve destruction. METHODS: All the newly opened AGV implants and the Aurolab aqueous drainage implants (AADI, used as controls) were tested by connecting to a 27-G cannula, open manometer, digital manometer, and automated infusion pump. Data logging was done using a digital manometer at 4 Hz using computerized software. When the AGV's flow characterization reached the steady phase, their valve functionality was destroyed by disrupting the valve leaflets, using a specially designed blade. The flow characteristics after valve slicing were compared with that of AADI. RESULTS: A total of 5 FP7 AGVs and 2 AADIs were tested. After initial resistance to flow (5, 8 mm Hg) observed in the case of AADI for 1 to 3 hours, it dropped to 1 mm Hg in both the implants. The flow-restrictive AGV showed 3 distinct phases in the flow characterization. The first phase included the transient phase followed by the steady phase wherein the pressure was 11.2±2.6 (min 7, max 14) mm Hg. The pressure resistance of the AGV dropped significantly (P<0.001) to a mean of 0.4±0.54 mm Hg (1 mm Hg in 2 devices and 0 mm Hg in 3 devices) after the valve functionality was destroyed. The average time taken for this drop in pressure resistance after valve slicing was 10.2±3.0 minutes (min 7, max 15). CONCLUSIONS: It was possible to convert the flow-restrictive AGV into a non-flow-restrictive device by destroying the functionality of the valve leaflets. The pressure of the AGVs was similar to AADI after destroying its valve functionality.

VST Centre for Glaucoma Care.

Full article

Classification:

12.8.2 With tube implant or other drainage devices (Part of: 12 Surgical treatment > 12.8 Filtering surgery)



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