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Karen Langenberg, Joey Tran, John Koontz, Malik Y Kahook; Flow Resistance and Suture Eyelet Integrity of the Ahmed ClearPath Glaucoma Drainage Device. Invest. Ophthalmol. Vis. Sci. 2020;61(7):3142.
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© ARVO (1962-2015); The Authors (2016-present)
The Ahmed ClearPath (ACP) is a valveless glaucoma drainage implant that received clearance from FDA via the 510(k) pathway with the Baerveldt Glaucoma Implant (BGI) as predicate device. This study was carried out to describe the pressure/flow characteristics and the suture eyelet integrity of these two devices.
In the first laboratory experiment, 30 ACP 350 mm2 and 3 BGI 350 mm2 were exposed to constant flow rates of 0.5, 2.0 and 5.0 µL/min in an aqueous (water) environment and pressure within the tube recorded via an Omega pressure transducer over a 2-hour test period to determine steady-state pressure during the second hour of testing at each flow rate. The acceptance criterion was a device resistance of <1 mmHg. In the second experiment, 30 ACP 350 mm2 and 3 BGI 350 mm2 were sequentially mounted in a force gauge and a 7-0 Vicryl suture was looped through each suture eyelet as separate trials (n=60 and 6 trials, respectively). Increasing force was applied to the suture until the eyelet failed. The acceptance criterion was device withstanding a minimum 0.5 newton force.
In the constant flow test, steady state pressures at flow rates of 0.5, 2.0, and 5.0 µL/min were 0.080, 0.062, and 0.238 mmHg, respectively for the ACP group and 0.064, 0.073, and 0.185 µL/min, respectively for the BGI group; the acceptance criterion was met for both devices. In the suture eyelet integrity test, the average force at failure was 13.6 newtons in the ACP group and 16.3 newtons in the BGI group and no single eyelet failed at <0.5 newtons; the acceptance criterion was met for both devices.
Flow restriction in the ACP tube is minimal and comparable to that of the BGI, and the suture eyelet integrity is satisfactory and comparable between devices.
This is a 2020 ARVO Annual Meeting abstract.
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