Chronic Ocular Hypertensive Rat Model using Microbead Injection: Comparison of Polyurethane, Polymethylmethacrylate, Silica and Polystyene Microbeads

• Published in: Current eye research Vol. 39; no. 9; pp. 917 - 927
• Main Authors: Rho, Seungsoo, Park, Insung, Seong, Gong Je, Lee, Naeun, Lee, Chang-Kyu, Hong, Samin, Kim, Chan Yun
• Format: Journal Article
• Language: English
• Published: England Informa Healthcare USA, Inc 01.09.2014; Taylor & Francis
• Subjects: Animals; Anterior Chamber - drug effects; Axons - pathology; Chronic Disease; Chronic ocular hypertension; Disease Models, Animal; Injections, Intraocular; Intraocular Pressure - drug effects; Male; microbead; Microspheres; Ocular Hypertension - etiology; Ocular Hypertension - physiopathology; optic nerve; Polymethyl Methacrylate - chemistry; Polystyrenes - chemistry; polyurethane; Polyurethanes - chemistry; rat; Rats; Rats, Sprague-Dawley; Retinal Ganglion Cells - pathology; Silicon Dioxide - chemistry; Suspensions - adverse effects; microbead; polyurethane; rat; Chronic ocular hypertension; optic nerve
• ISSN: 0271-3683; 1460-2202
• DOI: 10.3109/02713683.2014.884597

Abstract Purpose: To establish and assess an ocular hypertensive rat model using intracameral injection with various microbeads of different sizes and materials. Methods: Chronic elevation of intraocular pressure (IOP) was induced by the injection of various microbeads into the anterior chamber of Sprague-Dawley rat eyes. We compared the IOPs induced by the injection of different microbeads [7- and 17-µm polyurethane (PU), 7- and 15-µm polymethylmethacrylate (PMMA), 13-µm silica, and 15-µm polystyrene (PS)] and selected the appropriate microbeads for a chronic ocular hypertensive model in terms of IOP elevation and adverse events. IOP changes were observed for 4 weeks after microbead injections. Axonal degeneration was assessed with transmission electron microscopic photographs and RGC loss was assessed with retrograde labeling. Results: Seventy-eight rats were included. Three days after a single injection of microbeads, IOPs were increased by 24.0% by 7-µm PU microbeads, 101.8% by 17-µm PU microbeads, 56.6% by 7-µm PMMA microbeads, 22.0% by 15-µm PMMA microbeads, 153.0% by 13-µm silica microbeads, and 34.7% by 15-µm PS microbeads. 17-µm PU microbeads produced constant IOP elevation with good reproducibility (standard deviation of <6.5 mmHg). Silica injected eyes showed severe inflammation. Sustained IOP elevation by two injections of 17-µm PU microbeads resulted in a 42% axon loss and 36.5% RGC loss (p < 0.05, Mann-Whitney U test). Conclusions: PU microbead injections offer an applicable and versatile model for a chronic ocular hypertensive model in rats. Among several biomaterials, PU microbeads produced a more stable IOP elevation without adverse events.