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Jordan D Attwood, Vernard Woodley, Chintan Patel, Anish Kurian, Matthew S Lawrence; Reproducibility and inter-animal variability of electroretinography measures in African green monkeys. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5530.
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To assess the inherent inter-session variability in the standard International Society for the Clinical Electrophysiology of Vision (ISCEV) full field electroretinogram (ffERG) protocol and multifocal electroretinogram (mfERG) protocol in a group of normal African green monkeys, (Chlorocebus sabaeus) and to define the normal range for these parameters for the this species.
Both eyes from a group of 10 animals underwent 3 separate ffERG examines and 3 separate mfERG examines over the course of two weeks. The ffERG examine included a two scotopic adapted stimulus conditions (a single flash at 0.16 cd-s m2 and a single flash at 2.51 cd-s m2) and two photopic adapted stimulus conditions ( a single flash at 2.51 cd-s m2 and a 30 Hz flicker at 2.51 cd-s m2). Values were obtained for the a wave for the second and third stimulus conditions, b wave for the first three stimulus conditions, oscillator potentials (OP) for the stimulus second and third condition, and photopic negative response (PhNR) for the stimulus third condition. Measurement reliability for the amplitudes and their implicit times for these waveforms was determined by calculation of the 95% limits-of-agreement (LOA) and the coefficient-of-variation (COV) for each parameter. The mfERG data was compared qualitatively by overlapping the traces from the 3 time points of corresponding hexagons.
Clear waveforms with well-defined peaks were found in all the conditions for ffERG along with clear waveforms and strong signal for the mfERG. Inter session variability for amplitudes and latencies for the various peaks was relatively low. The variability between OD and OS within the same animals was also low, however the variability between animals was higher than either inter session or inter eye variability.
ERGs can be reliability and repeatedly measured in the green monkey and the species presents an appropriate test system for electrophysiology studies. Inter animal variability, however, should be considered when establishing study treatment groups, applying baseline data to randomized animals, and normalizing data by evaluating percent change from baseline for each group as opposed to absolute values. Comparatively low variability between OD and OS supports the use of the contralateral eye as a control where possible.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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