Abstract
Purpose: :
Beta-aminoproprionitrile (BAPN) and the chelating agent EDTA can reduce collagen cross-linking through different mechanisms of reduction of the activity of the enzyme lysyl oxidase. The purpose of this study was to investigate the effect of subconjunctival injection of these drugs on the hydraulic conductivity of the tissue capsule that forms after implantation of the Ahmed Glaucoma Valve.
Methods: :
Sub-Tenon’s implantation of the plate of the Ahmed Glaucoma Valve model FP-8 was performed in 15 New Zealand white rabbits. Animals received 0.5ml injections of beta-aminoproprionitrile (BAPN) 90 mg/ml, EDTA 0.12%, or balanced salt solution (BSS) every 48 hours for 3 weeks. After enucleation, measurements of hydraulic conductivity of the tissue capsule were performed by mounting each specimen across the lumen of a chamber designed to determine the rate of flow of BSS through the tissue while maintaining a constant pressure head with a column height of 1.35m. The coefficient of hydraulic conductivity was compared between the 3 groups.
Results: :
The mean coefficient of hydraulic conductivity in BAPN-treated eyes was (1.49 x 10-9 m/s/Pa). This was significantly greater than that of control eyes (1.38 x 10-10 m/s/Pa, p=0.009, Wilcoxon rank-sum test). EDTA-treated eyes had an intermediate level of hydraulic conductivity (5.41 x 10-10 m/s/Pa) that was not significantly different than the other groups.
Conclusions: :
Subconjunctival injection of the collagen cross-linking inhibitor BAPN increases the hydraulic conductivity of the tissue capsule formed around the Ahmed Glaucoma Valve. The results of this study suggest that modulation of the wound healing process by limitation of collagen cross-linking may be beneficial in improving the intraocular pressure outcome following implantation of a glaucoma implant.
Keywords: wound healing • intraocular pressure • clinical laboratory testing