Outflow Facility of a Glaucoma Valve Enclosed in Expanded Polytetrafluoroethylene (ePTFE)

Abstract

 

Abstract:

 

To compare the outflow facilities of two valved glaucoma implants in rabbits: a standard pediatric Ahmed Glaucoma Valve (S3) and an identical valve contained within a multilayered ePTFE enclosure (Integrated implant).

 

Ahmed S3 implants and Integrated implants were bilaterally implanted in fourteen normotensive rabbits. Intraocular pressure (IOP) measurements were taken and slit–lamp examinations were performed on post–op days 1, 3 and 7, then weekly up to 6 weeks. On the day of sacrifice, the anterior chamber tube of each implant was cannulated and pressure recordings were taken in situ at high and moderate perfusion rates of 5.0 and 2.0 µl/min, respectively, to determine outflow facility.

 

The data from 12 rabbits were analyzed. Two rabbits were excluded from the study due to implant failure. IOP of the Integrated implants (13.32±3.76mmHg) was higher than that of the Ahmed S3 implants (11.58±4.64mmHg) at post–op day 1 (p<0.05), and lower (8.28±1.55mmHg vs 9.54±1.76mmHg) at post–op week 2 (p< 0.05). Outflow facility curves were fitted for each implant during perfusions. (See figure.) The outflow facility was significantly higher in the Integrated implant compared with the Ahmed S3 implant at a 2ul/min flow rate (p < 0.01). There were no differences between the parameters of two curves at 5 µl/min.

 

The Integrated implant had greater outflow facility and a lower steady state pressure than the Ahmed implant when perfused at 2 µl/min in this non–glaucoma rabbit model. This new Integrated implants may have a possibility to be useful for glaucoma drainage surgery.

 

 

 

Keywords: wound healing