Experimental glaucoma model using polyurethane microbeads in rats

Abstract

AbstractPurpose To establish a new experimental glaucoma model using intracameral injection with various microbeads of different sizes and materials.Methods Chronic elevation of intraocular pressure (IOP) was induced by unilateral microbeads injection into the anterior chamber of Sprague‐Dawley (SD) rats. The effectiveness of different materials (polymethylmethacrylate (PMMA, 7 and 15 µm), polyurethane (PU, 7 and 17 µm), Silica (13 µm)) on IOP elevation was compared. Reinjection of the microbeads was performed at post‐injection day 7. Difference of IOP between both eyes was observed for 4 weeks. Axonal degeneration was assessed by the analysis of light microscopic and transmission electron microscopic photos.Results Total 54 SD rats weighing 250~300g initially were included in this study. After a single injection, the ratio of increased IOPs (mean value) at post‐injection day 3 were 56.6 %, 24.1 %, 23.8 %, 98.1 %, and 153.0 % in PMMA 7 µm, PMMA 15 µm, PU 7 µm, PU 17 µm, and Silica 13 µm, respectively. Since inter‐animal variability of PU 17 µm injected group was smaller than others, so that it was more adequate to produce constant IOP elevation with good repeatability (whereas Silica injected eyes showed severe inflammation). Sustained elevation of IOP by twice of PU 17 µm injection for at least 4 weeks resulted in approximately a 25.5 % loss of axon density (p=0.023, Mann‐Whitney U test). No axonal damage was noted in safety study group.Conclusion These data supports that the polyurethane microbeads injection is an applicable and versatile model for high tension glaucoma in rats. Among several biomaterials, PU showed more stable IOP elevation with safety. Future studies about suitable size and biomaterial of microbeads are more needed to secure this novel model.