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In vitro fluid dynamics of the Ahmed glaucoma valve modified with expanded polytetrafluoroethylene.

Publication ,  Journal Article
DeCroos, FC; Kondo, Y; Mordes, D; Lee, MR; Ahmad, S; Asrani, S; Allingham, RR; Olbrich, KC; Klitzman, B
Published in: Curr Eye Res
February 2011

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.

Duke Scholars

Published In

Curr Eye Res

DOI

EISSN

1460-2202

Publication Date

February 2011

Volume

36

Issue

2

Start / End Page

112 / 117

Location

England

Related Subject Headings

  • Transducers, Pressure
  • Sodium Chloride
  • Pressure
  • Polytetrafluoroethylene
  • Ophthalmology & Optometry
  • In Vitro Techniques
  • Hydrodynamics
  • Glaucoma Drainage Implants
  • Gelatin
 

Citation

APA
Chicago
ICMJE
MLA
NLM
DeCroos, F. C., Kondo, Y., Mordes, D., Lee, M. R., Ahmad, S., Asrani, S., … Klitzman, B. (2011). In vitro fluid dynamics of the Ahmed glaucoma valve modified with expanded polytetrafluoroethylene. Curr Eye Res, 36(2), 112–117. https://doi.org/10.3109/02713683.2010.512115
DeCroos, Francis Char, Yuji Kondo, Daniel Mordes, Maria Regina Lee, Sameer Ahmad, Sanjay Asrani, R Rand Allingham, Kevin C. Olbrich, and Bruce Klitzman. “In vitro fluid dynamics of the Ahmed glaucoma valve modified with expanded polytetrafluoroethylene.Curr Eye Res 36, no. 2 (February 2011): 112–17. https://doi.org/10.3109/02713683.2010.512115.
DeCroos FC, Kondo Y, Mordes D, Lee MR, Ahmad S, Asrani S, et al. In vitro fluid dynamics of the Ahmed glaucoma valve modified with expanded polytetrafluoroethylene. Curr Eye Res. 2011 Feb;36(2):112–7.
DeCroos, Francis Char, et al. “In vitro fluid dynamics of the Ahmed glaucoma valve modified with expanded polytetrafluoroethylene.Curr Eye Res, vol. 36, no. 2, Feb. 2011, pp. 112–17. Pubmed, doi:10.3109/02713683.2010.512115.
DeCroos FC, Kondo Y, Mordes D, Lee MR, Ahmad S, Asrani S, Allingham RR, Olbrich KC, Klitzman B. In vitro fluid dynamics of the Ahmed glaucoma valve modified with expanded polytetrafluoroethylene. Curr Eye Res. 2011 Feb;36(2):112–117.

Published In

Curr Eye Res

DOI

EISSN

1460-2202

Publication Date

February 2011

Volume

36

Issue

2

Start / End Page

112 / 117

Location

England

Related Subject Headings

  • Transducers, Pressure
  • Sodium Chloride
  • Pressure
  • Polytetrafluoroethylene
  • Ophthalmology & Optometry
  • In Vitro Techniques
  • Hydrodynamics
  • Glaucoma Drainage Implants
  • Gelatin