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Lakshmi P. Rajagopalan, Nimesh B. Patel, Ronald S. Harwerth, Laura J. Frishman; Loss of the photopic negative response of the multifocal electroretinogram in a nonhuman primate model of experimental glaucoma. Journal of Vision 2013;13(15):P37. doi: https://doi.org/10.1167/13.15.72.
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© ARVO (1962-2015); The Authors (2016-present)
The multifocal electroretinogram (mfERG) is a useful tool for objectively assessing localized functional changes at early stages of glaucoma, and as the disease progresses. The photopic negative response (PhNR) of the light-adapted full field ERG has been found to be reduced in glaucoma. We assessed the local loss of inner retinal function as reflected by the multifocal PhNR (mfPhNR) in a macaque model of experimental glaucoma. mfERGs were recorded longitudinally (5–10 visits) using VERIS 4.1 software in 3 macaque monkeys with unilateral intraocular hypertension (OHT) as a model of experimental glaucoma. The stimulus display, 35 deg × 34 deg , was an array of 19 unstretched hexagons. The m-sequence consisted of 5 bright frames, followed by 25 dark frames, repeating every 400 ms for 7 min. Relations between regional mfPhNR amplitude and corresponding retinal nerve fiber layer thickness (RNFLT) or with local subjective changes in visual sensitivity (VS) determined by behavioral perimetry were studied. Regional mfPhNR amplitudes were reduced in experimental eyes at early times when RNFLT was not different from that in control eyes (p<0.005, repeated measures ANOVA). Regional mfPhNR amplitudes were strongly correlated with the corresponding RNFLT (r>0.8, p<0.05, Pearson correlation) and moderately correlated with VS (r>0.4, p<0.05, Pearson correlation) in experimental eyes with RNFLT and VS losses, as well as in normal control eyes. These results indicate that the mfPhNR can be used as a tool to detect and monitor functional damage in primate eyes with OHT.
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