In vitro fluid dynamics of the Ahmed glaucoma valve modified with expanded polytetrafluoroethylene.
Curr Eye Res
; 36(2): 112-7, 2011 Feb.
Article
em En
| MEDLINE
| ID: mdl-21281065
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 ANDMETHODS:
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.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Politetrafluoretileno
/
Implantes para Drenagem de Glaucoma
/
Hidrodinâmica
Idioma:
En
Ano de publicação:
2011
Tipo de documento:
Article