TY - JOUR
T1 - The electroretinogram components in Abyssinian cats with hereditary retinal degeneration
AU - Kang Derwent, Jennifer J.
AU - Padnick-Silver, Lissa
AU - McRipley, Monique
AU - Giuliano, Elizabeth
AU - Linsenmeier, Robert A.
AU - Narfström, Kristina
PY - 2006/8
Y1 - 2006/8
N2 - PURPOSE. To examine phototransduction using the a-wave and other aspects of retinal function with the intraretinal b- and c-waves at different stages of an inherited photoreceptor degeneration in Abyssinian cats. METHODS. Vitreal and intraretinal ERGs were recorded from eight dark-adapted, anesthetized Abyssinian cats. Brief bright flashes were used to elicit vitreal a- and b-waves. Longer, weaker flashes were used to elicit intraretinal b- and c-waves. Stages 1 through 4 of the disease were characterized ophthalmoscopically. Parameters of the Lamb and Pugh a-wave model (amax, A, and teff) for the Abyssinian cats were compared with those for normal cats. Light microscopy was used to count photoreceptor nuclei. RESULTS. The maximum a-wave amplitude, amax, was significantly smaller in stage 1, and continued to decrease (stage 1: 50% of normal, stage 2: 28%, stage 3: 27%; and stage 4: unrecordable). There was a small, but not significant, decrease in the amplification constant A from 0.24 ± 0.11 s-2 in normal cats to 0.16 ± 0.08 s-2 in Abyssinian cats. The intraretinal b- and c-wave amplitudes decreased most dramatically during the early stage of the disease. Affected animals had fewer photoreceptors than unaffected Abyssinians or control animals. The number of photoreceptors declined most rapidly in the inferior periphery. CONCLUSIONS. The amplitudes of all ERG components were already reduced significantly by stage 1 and progressively declined. The lack of major changes in a-wave model parameters indicates that the degeneration is probably not due to a mutation in transduction proteins. Losses of photoreceptor function were larger than losses of photoreceptor nuclei.
AB - PURPOSE. To examine phototransduction using the a-wave and other aspects of retinal function with the intraretinal b- and c-waves at different stages of an inherited photoreceptor degeneration in Abyssinian cats. METHODS. Vitreal and intraretinal ERGs were recorded from eight dark-adapted, anesthetized Abyssinian cats. Brief bright flashes were used to elicit vitreal a- and b-waves. Longer, weaker flashes were used to elicit intraretinal b- and c-waves. Stages 1 through 4 of the disease were characterized ophthalmoscopically. Parameters of the Lamb and Pugh a-wave model (amax, A, and teff) for the Abyssinian cats were compared with those for normal cats. Light microscopy was used to count photoreceptor nuclei. RESULTS. The maximum a-wave amplitude, amax, was significantly smaller in stage 1, and continued to decrease (stage 1: 50% of normal, stage 2: 28%, stage 3: 27%; and stage 4: unrecordable). There was a small, but not significant, decrease in the amplification constant A from 0.24 ± 0.11 s-2 in normal cats to 0.16 ± 0.08 s-2 in Abyssinian cats. The intraretinal b- and c-wave amplitudes decreased most dramatically during the early stage of the disease. Affected animals had fewer photoreceptors than unaffected Abyssinians or control animals. The number of photoreceptors declined most rapidly in the inferior periphery. CONCLUSIONS. The amplitudes of all ERG components were already reduced significantly by stage 1 and progressively declined. The lack of major changes in a-wave model parameters indicates that the degeneration is probably not due to a mutation in transduction proteins. Losses of photoreceptor function were larger than losses of photoreceptor nuclei.
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U2 - 10.1167/iovs.05-1283
DO - 10.1167/iovs.05-1283
M3 - Article
C2 - 16877442
AN - SCOPUS:33748109425
SN - 0146-0404
VL - 47
SP - 3673
EP - 3682
JO - Investigative Ophthalmology and Visual Science
JF - Investigative Ophthalmology and Visual Science
IS - 8
ER -