In vitro fluid dynamics of the Ahmed glaucoma valve modified with expanded polytetrafluoroethylene.
Date
2011-02
Journal Title
Journal ISSN
Volume Title
Repository Usage Stats
views
downloads
Citation Stats
Abstract
PURPOSE: 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). MATERIALS AND 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.
Type
Department
Description
Provenance
Citation
Permalink
Published Version (Please cite this version)
Publication Info
DeCroos, Francis Char, Yuji Kondo, Daniel Mordes, Maria Regina Lee, Sameer Ahmad, Sanjay Asrani, R Rand Allingham, Kevin C Olbrich, et al. (2011). In vitro fluid dynamics of the Ahmed glaucoma valve modified with expanded polytetrafluoroethylene. Curr Eye Res, 36(2). pp. 112–117. 10.3109/02713683.2010.512115 Retrieved from https://hdl.handle.net/10161/10348.
This is constructed from limited available data and may be imprecise. To cite this article, please review & use the official citation provided by the journal.
Collections
Scholars@Duke
Sanjay Girdhari Asrani
Sanjay Asrani, MD, specializes in glaucoma diagnosis and treatment, and cataract surgery. He is highly skilled in all forms of cataract and glaucoma surgery including tube implant, laser and filtering surgery. He is board certified, fellowship trained, and has been honored among “America’s Top Ophthalmologists” and “Best Doctors in America”.
Asrani is a dedicated researcher receiving support from Research to Prevent Blindness, private foundations, and philanthropy. His major research interests include the development of new surgical implants for glaucoma, and the development and utilization of new technology for the early detection of glaucoma.
Bruce Klitzman
Our overriding interests are in the fields of tissue engineering, wound healing, biosensors, and long term improvement of medical device implantation. My basic research interests are in the area of physiological mechanisms of optimizing substrate transport to tissue. This broad topic covers studies on a whole animal, whole organ, hemorheological, microvascular, cellular, ultrastructural, and molecular level. The current projects include:
1) control of blood flow and flow distribution in the microcirculation,
2) the effects of long-term synthetic and biologic implants on substrate transport to tissues,
3) tissue engineering; combining isolated cells, especially adult stem cells, with biomaterials to form specialized composite structures for implantation, with particular emphasis on endothelial cell physiology and its alteration by isolation and seeding on biomaterials.
4) decreasing the thrombogenicity of synthetic blood vessels and other blood-contacting devices, and improving their overall performance and biocompatibility.
5) reducing tissue damage resulting from abnormal perfusion (e.g., relative ischemia, anoxia, etc.) and therapies which minimize ischemic damage.
6) biosensor function, particularly glucose sensors in normal and diabetics.
7) measurement of tissue blood flow and oxygenation as an indicator of tissue viability and functional potential.
8) development of biocompatible materials for soft tissue reconstruction or augmentation.
9) improving performance of glaucoma drainage devices by directing a more favorable foreign body reaction
10) wound healing; particularly internal healing around foreign materials and the effect and prevention of microbes around implanted devices.
Unless otherwise indicated, scholarly articles published by Duke faculty members are made available here with a CC-BY-NC (Creative Commons Attribution Non-Commercial) license, as enabled by the Duke Open Access Policy. If you wish to use the materials in ways not already permitted under CC-BY-NC, please consult the copyright owner. Other materials are made available here through the author’s grant of a non-exclusive license to make their work openly accessible.