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Aging, background luminance, and threshold-duration functions for detection of low spatial frequency sinusoidal
Purpose:
This study examined the temporal summation properties of the aging visual system under a wide range of background luminances.
Methods:
Contrast thresholds for 0.5 cpd gratings for 12 younger (mean age 20.6 years) and 12 older (mean age 71.6 years) observers in good ocular health were measured for 6 stimulus durations (from 10 to 1000 ms) under 4 background luminances (from 0.44 to 249.50 cd/m2). Two-alternative forced-choice staircase method was used.
Results:
We found significant main effects of age, background luminance, and stimulus duration on the contrast threshold. There were no age-related differences in the shape of the threshold-duration functions under all background luminances, although the shape changed significantly with background luminance. Age-related differences in contrast threshold were significant under the two lowest, but not under the two highest, background luminances.
Conclusions:
Age-related alteration in visual sensitivity may be attributed to sensitivity (amplitude) losses but not to changes in temporal characteristics of the visual system.