Abstract
Abstract: :
Purpose: To investigate whether the scotopic flash ERG is affected in the vein-occlusion induced glaucoma model in Brown-Norway male rats. Methods: Seven retired breeder Brown-Norway male rats (age≷ 8 months) were subjected to a baseline intraocular pressure(IOP) measurement using the Tonopen XL. In this group of animals uniocular IOP elevation was induced by cauterization of three episcleral/extra-orbital veins.A second group of 7 normal rats of the same strain and age were used as controls.Three months after the induction of elevated IOP scotopic ERGs were recorded simultaneously in both eyes of anesthetized, dark-adapted animals. ERG recordings were performed using attenuated light flashes, and were analysed to determine the amplitudes of a and b waves and oscillatory potentials (OPs), which were calculated using the RMS technique. Results: IOP was significantly elevated for up to 3 months in eyes subjected to episcleral vein cauterization compared to contralateral non-operated eyes (p<0.023) The IOP in contralateral eyes of control animals showed no significant difference.No significant differences in a and b wave amplitude and OPs were detected in contralateral eyes of control rats. Contralateral eyes of experimental animals did not show a significant difference in a and b wave amplitudes ( p=0.40 and p=0.094) respectively. However,a statistically significant reduction (p=0.00153)in OPs in eyes with elevated IOP (51.314.7µV,meanSD ) compared to contralateral eyes (71.723µV,mean SD) was detected in the experimental group of rats. Conclusion: OPs are a sensitive measure of functional changes in the retina, induced by IOP elevation using the episcleral vein-occlusion procedure in older male Brown-Norway rats. These results provide additional evidence of the utility of scotopic OPs as a monitor of glaucomatous progression in rat glaucoma models.
Keywords: 394 electrophysiology: non-clinical • 316 animal model • 444 intraocular pressure