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JN Ver Hoeve, CB Y Kim, RW Nickells, PL Kaufman, GA Heatley, B Faha, TM Nork; Recovery Of A Late Multifocal ERG Waveform Complex In Experimental Ocular Hypertension Following IOP Reduction . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2121.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To describe changes in the multifocal ERG (mERG) in a non-human primate model of glaucoma following lowering of intraocular pressure (IOP) via trabeculectomy. Methods:Unilateral ocular hypertension was induced in 5 young adult cynomolgus monkeys by argon laser trabecular meshwork destruction (ALTD) of one eye. At the time of the first mERG test, IOPs ranged from 23-51 mm Hg in the ALTD eyes and 12-17 mm Hg in the fellow eyes. IOP was then lowered by trabeculectomy surgery. At the final mERG test 259-308 days later, IOPs ranged from 9-21 mm Hg in the ALTD/trabeculectomy eyes and 13-22 mm Hg in the fellow eyes. mERG recordings were obtained from the control and hypertensive eyes using a standard stimulus consisting of 103 equal sized hexagonal elements, which subtended ± 44 deg around the central visual axis. The base rate was 13.3 ms. First order kernel mERG waveforms were averaged for 4 rings radiating from the foveal element. Amplitudes and implicit times of the first 4 waves were measured for each of the 4 rings. The effect of trabeculectomy was assessed by analysis of variance (ANOVA) with Eye, Test session, and Eccentricity (rings) of the mERG response as factors. Results:At the time of the first test, a late negative-positive wave complex (48-70 ms) of the first-order kernel mERG response was significantly reduced in ALTD as compared to fellow eyes. Implicit times of the early waves were delayed in ALTD eyes. Following trabeculectomy and lowering of IOP, there was recovery of the late wave complex amplitude, which was confirmed by significant interactions between Eye and Test session in the ANOVA. Implicit times did not show recovery. Conclusion:ollowing ALTD-induced ocular hypertension, a first order kernel waveform complex occurring 48-70 ms following light onset becomes markedly attenuated in the mERG. This portion of the mERG may show recovery of amplitude following surgical lowering of IOP.
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