Porosity of Bleb Capsule declines rapidly with Fluid Challenge

Surinder S Pandav; Craig M Ross; Faisal Thattaruthody; Ritambhra Nada; Nirbhai Singh; Natasha Gautam; Stephen Beirne; Gordon G Wallace; Mark B Sherwood; Jonathan G Crowston; Michael Coote

doi:10.5005/jp-journals-10008-1208

Porosity of Bleb Capsule declines rapidly with Fluid Challenge

J Curr Glaucoma Pract. 2016 Sep-Dec;10(3):91-96. doi: 10.5005/jp-journals-10008-1208. Epub 2016 Oct 29.

Authors

Affiliations

¹ Professor, Advanced Eye Center, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
² Research Fellow, Center for Eye Research Australia, University of Melbourne Melbourne, Victoria, Australia.
³ Senior Registrar, Advanced Eye Center, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
⁴ Professor, Department of Pathology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
⁵ Assistant Professor, Advanced Eye Center, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
⁶ Senior Research Fellow, Intelligent Polymer Research Institute/AIIM Faculty, University of Wollongong, Wollongong, New South Wales, Australia.
⁷ Professor, Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, University of Wollongong Wollongong, New South Wales, Australia.
⁸ Professor, Department of Ophthalmology, University of Florida, Gainesville Florida, United States.
⁹ Managing Director, Center for Eye Research Australia, University of Melbourne Melbourne, Victoria, Australia.
¹⁰ Associate Professor, Center for Eye Research Australia, University of Melbourne Melbourne, Victoria, Australia.

Abstract

Introduction: The porosity of the fibrous capsule around a glaucoma drainage device (GDD) may be the most important functional attribute. The factors that determine capsular porosity are not well understood. Failed GDD surgeries are usually associated with thick impervious capsules and components of aqueous have been implicated in this process.

Purpose: In this study, we interrogated the effect of passage of nonaqueous fluid on capsular porosity in mature (but aqueous naïve) blebs in a previously reported GDD model (the "Center for Eye Research Australia Implant").

Materials and methods: The study was performed at two centers using 17 New Zealand White (NZW) rabbits. An experimental GDD was implanted into the subconjunctival space but without connection to the anterior chamber. After 28 days, balanced salt solution (BSS) was passed through the implant for 30 to 40 minutes at 12 mm Hg. Capsular porosity was measured as flow (μL/min) at a constant pressure. Porosity of the capsule was retested at 3 and 6 days.

Results: There was a marked reduction in capsular porosity within 3 days of exposure to BSS (fluid challenge). Even though the baseline porosity was significantly different in the two groups (3.00 ± 0.5 μL/min and 29.67 ± 12.12 μL/min, p < 0.001), the effect of passage of BSS was similar. Capsular porosity fell by approximately 80% in both groups from baseline after single BSS challenge. Capsular thickness was significantly less in Advanced Eye Center (AEC) rabbits at baseline. There was no change in the capsular thickness before and after single fluid challenge.

Conclusion: Passage of BSS at physiological pressures for under 40 minutes caused marked reduction in the porosity of the fibrous capsule within 3 days. This was not associated with any significant thickening of the fibrous capsule within this time frame.

How to cite this article: Pandav SS, Ross CM, Thattaruthody F, Nada R, Singh N, Gautam N, Beirne S, Wallace GG, Sherwood MB, Crowston JG, Coote M. Porosity of Bleb Capsule declines rapidly with Fluid Challenge. J Curr Glaucoma Pract 2016;10(3):91-96.

Keywords: 3D Printed implant; Aqueous outflow; Capsular porosity; Filtering surgery; Glaucoma; Glaucoma drainage device; Hydraulic conductivity; Rabbit model; Rapid failure..