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S. G. Rosolen, J.-F. LeGargasson, E. Dubus, S. Picaud, S. Lavillegrand, P. Lachapelle; The Effect of Aging on the Retinal Function in Two Selected Breed of Dogs. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5577.
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© ARVO (1962-2015); The Authors (2016-present)
Although rodents are commonly used in vision research, due to their relatively short life expectancy, they offer limited possibilities when investigating age-related phenomenon. In contrast, dogs represent a better model due to the fact that their life expectancy increased significantly to the point that most of the pet dogs now die of old age. The purpose of this study was to compare the effect of aging on the retinal function of two selected breeds of dogs with similar size and weight (miniature Poodles and Yorkshire terriers).
For all animals, the inclusion criteria were: clear media and absence of systemic diseases. Binocular, full-field photopic and scotopic ERGs were recorded from fully anaesthetized young (age range: 3-5 years) miniature poodles (YmP; n=6) and young Yorkshire terriers (YT; n=6) and old (age range: 10-14 years) miniature poodles (OmP; n=6) and old Yorkshire terriers (OY; n=6) . Photopic ERGs were evoked in responses to series of flashes (ranging from -3.99 log cds/m2 to 0.81 log cds/m2) in order to extract Vmax and log K parameter from the luminance-response curves. Flicker ERGs were measured at 30 Hz. In scotopic conditions, the ERGs were evoked in responses to 5 dim flash (intensity: -2.50 log cds/m2) delivered at 0.1 Hz after 30 minutes of dark adaptation.
The mean (SD) photopic Vmax values were 194.7±49.0 µV for the YmP, 135.8±23.1 µV for OmP, 126.0±5.5 µV for YY and 84.3±14.1 µV for OY, respectively. The mean (SD) values of log K were -1.52±0.38 for YmP, -1.39±0.22 for OmP, -1.64±0.31 for YY and -1.78±0.35 for OY, respectively. The mean (SD) scotopic b-wave amplitudes were 164.5±17.0 µV for YmP, 138.0±4.9 µV for OmP, 162.2±11.8 µV for YY and 132.2±14.1 µV for OY, respectively. Photopic flicker parameters values and implicit times values were similar for all groups.
The implicit times are not age-dependent. In photopic and scotopic conditions, our results indicate that the b-wave amplitudes mediated by either cone and rod pathways decrease with age. This decrease represents 30% in photopic conditions and 15% in scotopic conditions. Interestingly, the Vmax values are significantly larger in miniature Poodles in comparison with Yorkshire Terriers, indicating the necessity to establish normative data for each breed when ERG assessments are performed
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