title: Electroretinographic abnormalities in a rat glaucoma model with chronic elevated intraocular pressure.
abstract: The purpose of this study was to determine the ability of electroretinographic (ERG) measurements to document progression of the retinopathy in a rat glaucoma model. Thirty four rats with a chronic intraocular pressure (IOP) elevation induced in one eye by cautery of three episcleral/extra-orbital veins were studied in four separate groups. ERGs were recorded sequentially in Group A rats (n = 12) at baseline, and after approximately 20, 40 and 60 days of high IOP, and in three additional groups of rats (n = 6 or 10 per group) after approximately 58, 30 and 175 days of high IOP, respectively. Scotopic ERG parameters recorded simultaneously from both eyes in Group A rats were: a- and b-wave amplitudes, implicit times, oscillatory potential amplitudes (OPs) determined at three different light-flash intensities, and the light-adapted (photopic) ERG b-wave amplitude. In the other groups of rats, only scotopic ERG a-wave, b-wave and OP amplitudes were measured.In Group A rats that were followed sequentially, all the ERG parameters recorded with attenuated stimuli showed significant time-dependent changes in glaucomatous eyes relative to their contralateral normal eyes, with OPs showing the earliest significant difference after only 3 weeks of high IOP. When different groups of unilateral glaucomatous rats were compared beyond 8 weeks of elevated IOP only the OPs showed a continued decrease with time and good discrimination between glaucoma and normal eyes. Over a 25 week period of high IOP the scotopic OPs measured with attenuated light stimuli declined at the rate of approximately 1.5% per week and provided the best ERG measure to monitor progression of retinal pathophysiology in the vein-occlusion rat glaucoma model.
authors.affiliation: Department of Ophthalmology, Mount Sinai School of Medicine of New York University, New York, U.S.A.
authors.forename: A U
authors.initials: AU
authors.lastname: Bayer
authors.forename: J
authors.initials: J
authors.lastname: Danias
authors.forename: S
authors.initials: S
authors.lastname: Brodie
authors.forename: K P
authors.initials: KP
authors.lastname: Maag
authors.forename: B
authors.initials: B
authors.lastname: Chen
authors.forename: F
authors.initials: F
authors.lastname: Shen
authors.forename: S M
authors.initials: SM
authors.lastname: Podos
authors.forename: T W
authors.initials: TW
authors.lastname: Mittag
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D018450:Disease Progression; D004596:Electroretinography / Q000379:methods; D005260:Female; D005583:Fourier Analysis; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D016014:Linear Models; D016015:Logistic Models; D016011:Normal Distribution; D012372:ROC Curve; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity; D013997:Time Factors