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Y. Katagiri, L. M. Franco, P. J. Rychwalski, L. Liang, J. H. Sandell, J. F. Rizzo, H. J. Kaplan, V. Enzmann; Functional and Structural Recovery in a Rabbit Model of Photoreceptor Degeneration. Invest. Ophthalmol. Vis. Sci. 2007;48(13):4501.
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© ARVO (1962-2015); The Authors (2016-present)
This work is related to the efforts of the Boston Retinal Implant Project to develop a sub-retinal prosthesis to restore vision to the blind. The specific purpose of the presentation is to study the electrophysiological and morphological changes in the neurosensory retina (NSR) of rabbits following iodoacetic acid (IAA) injection causing photoreceptor degeneration.
Adult Dutch-belted rabbits (n=4) were injected intravenously with IAA (20 mg/kg body weight). Dark adapted and light adapted ERGs were recorded before injection and 1, 7 and 14 days, as well as 1, 3 and 6 months after IAA injection. Additionally, rabbit eyes were investigated by light microscopy (LM) and immunohistology (IH) at the same time points.
The b-wave amplitude of the dark adapted ERG was significantly diminished after IAA injection compared to pre-injection (174.4 ± 18.0 µV). This effects was beginning on day 7 where measurements showed the lowest amplitude (49.1 ± 17.0 µV) but a significant recovery was observed at 14 days (111.6 ± 22.5 µV), 1 month (174.3 ± 25.1 µV), 3 months (111.1 ± 23.0 µV) and 6 months (209± 34 µV). The b-wave amplitude of the light adapted ERG was also significantly diminished 1 day after IAA injection (11.1 ± 5.1 µV) compared to pre-injection (124.1 ± 14.9 µV). Significant recovery was observed at 7 days (53.2 ± 11.4 µV), 14 days (68.7 ± 20.2 µV), 1 month (83.1 ± 12.3 µV), 3 months (49.0 ± 8.1 µV) and 6 months (104± 11.0 µV). LM and IH demonstrated that damage was confined to the photoreceptors and most severe in the ventral retina. Horizontal and rod bipolar cells were intact and in normal numbers, even when the outer nuclear layer was completely degenerated. The damage observed after 6 months is less extensive than at earlier times. Although the extent of structural damage caused by the toxin was variable, there was definite morphologic and functional recovery over time.
IAA caused functional and structural damage confined to the outer retina, with apparent recovery of both function and structure over time.
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