Senescent changes in scotopic contrast sensitivity.
Scotopic contrast sensitivity functions (CSFs) were measured for 50 observers between the ages of 20 and 88 years. Using a maximum-likelihood, 2-alternative, temporal forced-choice threshold-estimation algorithm, scotopic CSFs were measured at 7 spatial frequencies ranging from 0.2 to 3.0 cpd, with mean retinal illuminance equated for observers at -0.85 log scotopic Trolands. For each stimulus condition, eight cycles of a horizontal sinusoidal grating were presented within +/- 1 S.D. of a 2-D Gaussian-spatial envelope and within a 1-s Gaussian-temporal envelope. Stimuli were centered on the nasal retina along the horizontal meridian 6 degrees from the fovea. Scotopic CSFs were found to be low-pass. Statistically significant age-related declines in contrast sensitivities were found for spatial frequencies at or below 1.2 cpd. There was also a statistically significant decrease in the high frequency cut-off with age (P < 0.01). An explanation of these results in terms of optical factors is rejected, while the results are consistent with age-related changes in the magnocellular pathway.
Schefrin
B E
BE
Department of Psychology, University of Colorado, Boulder 80309-0345, USA. brooke@psych.colorado.edu
Tregear
S J
SJ
Harvey
L O
LO
Werner
J S
JS
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D010775:Photic Stimulation; D012684:Sensory Thresholds / Q000502:physiology