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S.G. Rosolen, P. Lachapelle, S. Lavillegrand, J.–A. Sahel, J.–F. Le Gargasson; The Effect Of Aging On The Cone Function In Dogs . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3085.
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© ARVO (1962-2015); The Authors (2016-present)
With the progress of veterinary medicine, the life expectancy of the domestic dog has increased significantly to the point that it is not unusual for most of them to die of old age, somewhat similar to human beings. Dogs could therefore potentially represent an interesting animal model to study the effect of normal aging on retinal function.
For all animals, inclusion criteria were: absence of ocular opacities and absence of systemic diseases. Binocular, full field photopic flash and flicker ERGs were recorded from fully anaesthetised young Poodles (YP;n=6) and young Yorkshire Terriers (YY; n=6)(age range:3–5 years old) and old Poodles (OP; n=5) and old Yorkshire Terriers (OY; n=6)(age range:10–14 years old). The photopic flicker retinal responses were evoked at 4 different temporal frequencies (6Hz, 12Hz, 20Hz and 30Hz). The ERGs were evoked in responses to 20 different flashes of increasing intensities presented in photopic conditions from which we derived luminance–response curve parameters Vmax and log K.
The mean (SD) photopic Vmax values were 194.67(49.03)µV for the YP, 135.80(23.13)µV for the OP, 126.00(5.48)µV for the YY and 84.33(14.14)µV for the OY, respectively. No significant changes in implicit times measured at the Vmax nor in flicker mean amplitude were observed. The calculated mean (SD) values of log K were –1.52(0.38) for YP, –1.39(0.22) for OP, –1.64(0.31) for YY and –1.78(0.35) for OY.
Our results clearly indicate that the cone sensitivity decreases with age in dogs. Interestingly, despite the fact the Vmax values are significantly larger in Poodles than in Yorkshire Terriers, in both breeds the cone Vmax is reduced by 30% with age (i.e. young vs old) suggesting that this could represent a common feature of the normal aging process of the retina.
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