Morphometric changes in the rat retina following carbomer induced elevations in intraocular pressure

Abstract

An elevated intraocular pressure (IOP) model was established in rats by injecting a carbomer suspension loaded on a nanomaterial vector into the anterior chamber. Characteristics of elevated IOP caused by carbomer were assessed by examining effects on hypertension, and for the anterior segment and retinal morphometric changes. Baseline IOP was measured in twenty-four Sprague Dawley (SD) rats were selected and was measured twice for three days preoperatively. After treatment, we found a significant difference between day and night in experimental eyes and between day and night in control eyes (all P <0.05). Later post-injection, fluctuations in IOP decreased significantly. We found a large difference in mean IOP between experimental and control eyes during the day (P <0.05). The anterior chamber of experimental eyes was filled with a mixture of carbomer and iris, which was close to the corneal endothelium, extended to the anterior chamber angle, and blocked the trabecular meshwork structure. After four weeks, pressure-induced morphological damage of retina was observed by H&E staining and ERG. Apoptosis was detected in the retinal ganglion cell layer by TUNEL staining. Carbomer induced increased IOP was maintained for more than four weeks. Elevated IOP was significantly different between day and night, with night pressure higher.