Purchase this article with an account.
P. Farhi, L. Kagemann, M. Kahook, J. Schuman, R. Noecker; The Utility of Venting Slits and Punctures in Modifying Glaucoma Drainage Device Outflow Facility . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5489.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Venting slits or punctures are commonly used to prevent intraocular pressure spikes in the early post–operative period when the silicone tubes of glaucoma drainage devices are occluded. This study evaluates the efficacy of these techniques in allowing fluid to filter through the tubes at various pressures.
16 Silicone tubes were obtained from Baerveldt BG101–350 glaucoma implants. One end of each tube was linked to a 25 gauge (G) needle connected to a column of water equipped with a pressure sensor. The opposite end of each tube was securely ligated creating a closed, air–free system. Four different types of openings were made in the silicone tubes. Single openings were created with a 1) 30.5 G needle, 2) 25 G needle, 3) 1 mm longitudinal slit, or 4) 2 mm longitudinal slit made with a #11 scalpel. Internal fluid pressure was then increased from 0 to 90 mmHg in an incremental fashion. The pressure was allowed to equilibrate in increments of 10 mmHg while the tube was examined for leakage. Leaking was defined as formation of a droplet on the tube that reformed after removal. The pressures at which leakage occurred were compared by non–parametric unpaired Mann–Whitney comparisons.
The mean pressure that a 30.5 G needle hole began to leak at was 43.33 ± 5.77 mmHg. The mean pressure at which a 25 G needle hole began to leak was 36.25 ± 16.54 mmHg (n=4). The difference between these groups was not statistically significant (p=0.686). However, no leakage could be induced from either the 1 mm or the 2 mm slits at pressures up to 90 mmHg.
Creation of 1 or 2 mm venting slits through silicone tubes failed to relieve fluid pressure in the laboratory setting. Needle punctures began to leak at pressures between 35 and 45 mmHg. Needle puncture of the silicone tube may represent a viable option for early post–operative pressure control in ligated glaucoma drainage devices.
This PDF is available to Subscribers Only