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L.M. Franco, Y. Katagiri, Y. Yamauchi, D. Jackson, J.F. Rizzo, III, O.R. Ziv, H.J. Kaplan, V. Enzmann; Elevated Retinal Thresholds With a Subretinal Microelectrode Array in a Rabbit Model of Photoreceptor Degeneration . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3169.
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© ARVO (1962-2015); The Authors (2016-present)
To study the electrophysiological changes in the neurosensory retina (NSR) and the response in the visual cortex of rabbits following iodoacetic acid (IAA) injection causing photoreceptor degeneration.
Adult Dutch–belted rabbits were injected intravenously with IAA (20 mg/kg body weight). The electrodes for visual evoked potentials (VEP) and electrical evoked potentials (EEP) were placed on the dura mater overlying the visual cortex. A stroboscope generated the stimulation for the VEP and a 5x5 microelectrode array (MEA), placed in the subretinal space, provided the stimulus for the EEP. Both VEP and EEP were recorded 14 days, 1 month, 3 months and 6 months after IAA injection. Normal rabbits were used as controls.
The VEP amplitude was significantly diminished after IAA injection compared to control eyes (normal = 260.5 ± 75.1 µV). The lowest amplitude was observed at 14 days (49.7 ± 21.5 µV); however, a statistically significant recovery was observed at 1 month (204.3 ± 127.8 µV), 3 months (179.7 ± 101.0 µV), and 6 months (203.1 ± 41.1 µV). The EEP threshold significantly increased over time after IAA injection (e.g., at 1 month = 53.1 ± 17.9 nC) compared to controls (9.2 ± 2.9 nC) but recovered over time (e.g., at 6 months = 37.5 ± 19.1 nC). Likewise, the VEP amplitude in these eyes showed recovery over the 6 months time interval (control = 345.2 ± 46.1 µV; 1 month = 138 ± 46.7 µV; 6 months = 355 ± 151.9 µV).
IAA significantly elevated the retinal threshold in a rabbit model of photoreceptor degeneration using a subretinal MEA to elicit an EEP. However, the electrophysiological changes caused by IAA at the dosage used appear to be transient and reversible.
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