|
| Publications [#196430] of Bruce M. Klitzman
Papers Published
- FC DeCroos, Y Kondo, D Mordes, MR Lee, S Ahmad, S Asrani, RR Allingham, KC Olbrich, B Klitzman, In vitro fluid dynamics of the Ahmed glaucoma valve modified with expanded polytetrafluoroethylene.,
Current eye research, vol. 36 no. 2
(February, 2011),
pp. 112-7, ISSN 1460-2202 [doi]
(last updated on 2012/03/07)
Abstract:
OBJECTIVE: Long-term intraocular pressure reduction by glaucoma drainage devices (GDDs) is often limited by the fibrotic capsule that forms around them. Prior work demonstrates that modifying a GDD with a porous membrane promotes a vascularized and more permeable capsule. This work examines the in vitro fluid dynamics of the Ahmed valve after enclosing the outflow tract with a porous membrane of expanded polytetrafluoroethylene (ePTFE). METHODS: The control and modified Ahmed implants (termed porous retrofitted implant with modified enclosure or PRIME-Ahmed) were submerged in saline and gelatin and perfused in a system that monitored flow (Q) and pressure (P). Flow rates of 1-50 μl/min were applied and steady state pressure recorded. Resistance was calculated by dividing pressure by flow. RESULTS: Modifying the Ahmed valve implant outflow with expanded ePTFE increased pressure and resistance. Pressure at a flow of 2 μl/min was increased in the PRIME-Ahmed (11.6 ± 1.5 mm Hg) relative to the control implant (6.5 ± 1.2 mm Hg). Resistance at a flow of 2 μl/min was increased in the PRIME-Ahmed (5.8 ± 0.8 mm Hg/μl/min) when compared to the control implant (3.2 ± 0.6 mm Hg/μl/min). CONCLUSIONS: Modifying the outflow tract of the Ahmed valve with a porous membrane adds resistance that decreases with increasing flow. The Ahmed valve implant behaves as a variable resistor. It is partially open at low pressures and provides reduced resistance at physiologic flow rates.
Keywords:
Gelatin • Glaucoma Drainage Implants* • Hydrodynamics* • Polytetrafluoroethylene • Pressure • Sodium Chloride • Transducers, Pressure • chemistry* • metabolism
|
