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M. B. Jeong, Y. J. Pak, K. Narfström; Assessment of Retinal Function in Normal Cats and in Cats Affected with the CEP290 Mutation Using Scotopic and Photopic ERG Light Intensity Series. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4508.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate retinal function using scotopic and photopic light intensity series in normal cats and in cats affected with stages of recessively inherited rod cone degeneration caused by the CEP290 mutation for precise sensitivity measurements.
Twenty-nine cats, aged 0.3-8.2 yrs, were divided into 3 groups based on disease stage (group I: 0.3-1.5 yrs, group II: 1.6-4.5 yrs, group III: 4.6-8.2 yrs) and 16 normal cats of similar ages into 3 control groups. Scotopic and photopic light-intensity series were performed under general anesthesia, using mini-Ganzfeld ERG (HMsERG, RetVetCorp. Inc. Columbia, MO). Light stimulus was increased in intervals of 0.5 log units from -4.0 to 1.4 log cd.s/m2 in scotopic conditions and, after 10 min of light adaptation, from -2.0 to 1.4 log cd.s/m2 (25 cd.s/m2) for the photopic series. Naka-Rushton function (NR) was fitted to scotopic b-wave amplitudes and intensity-response relationships were plotted for the scotopic and photopic ERGs.
No significant differences in the NR parameters (Vmax, n, and Log K) were observed between affected and controls. Using intensity-response relationships, however, scotopic b-wave amplitudes for normal cats were significantly higher than those of affected cats from -2.5 to 1.4 log cd.s/m2 and similarly for photopic amplitudes from 1.0 to 1.4 log cd.s/m2 for group III (P<0.05). Amplitudes of photopic b-waves for normal cats in all groups continued to increase with the highest light intensity used (1.4 log cd.s/m2), whereas in affected cats of all groups b-wave amplitudes reached a peak at 0.5 log cd.s/m2 and decreased thereafter.
The CEP290 protein is important for maintenance of photoreceptor function and reduction in scotopic a-wave amplitude concurrent with reduction in retinal oxygenation in mutant animals have been previously reported. The present study elucidated yet another abnormal parameter in rdAc mutant with the CEP290 mutation: alterations in photopic ERG responses to high levels of light stimulation.
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