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Anne B. Fulton, Ronald M. Hansen; The Development of Scotopic Sensitivity. Invest. Ophthalmol. Vis. Sci. 2000;41(6):1588-1596.
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purpose. Test the hypothesis that the developmental increases in rod
photoreceptor sensitivity and rod-mediated visual sensitivity at 10°,
20°, and 30° eccentric are concurrent. It is known that maturation
of the parafoveal (10° eccentric) rod outer segments and visual
sensitivity is delayed compared to that at 30° eccentric.
methods. Rod isolated electroretinographic (ERG) responses to full-field stimuli
were obtained from dark-adapted subjects (n = 71),
ranging in age from early infancy through middle age. Rod photoreceptor
sensitivity was calculated by fitting a model of the activation of
phototransduction to the a-wave response. Rod driven b-wave sensitivity
was calculated from stimulus–response functions. A logistic growth
model was used to summarize the developmental increases in sensitivity
of the rod photoreceptors and the b-wave. Previously reported
dark-adapted, rod-mediated visual sensitivities at 10°, 20°, and
30° eccentric, obtained using preferential looking procedures, were
reanalyzed using the logistic growth model.
results. The logistic growth model accounted for 57% to 85% of the variance of
each sensitivity parameter with age in normal subjects. The shape of
the growth curve and the age at which sensitivity reaches 50% of the
adult value is similar (10.0–13.5 weeks) for the rods, the b-wave, and
peripheral visual sensitivity, but is significantly older, 19.5 weeks,
for rod-mediated parafoveal visual sensitivity.
conclusions. Rod photoreceptor sensitivity and peripheral, rod-mediated visual
sensitivity develop concurrently. A parsimonious explanation is that
rod photoreceptor sensitivity determines dark-adapted, rod-mediated
visual sensitivity during development.
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