Purpose. A common visual problem of older adults is difficulty seeing under reduced illumination and at night. Scotopic sensitivity was compared in old and young adults taking into account lens density differences. Unlike earlier studies, standardized grading scales were used to assess retina (WARMGS) and lens (LOCS III) characteristics, in order to document eye health characteristics of the older sample. Methods. 24 older adults (range 65-75 yrs) and 25 younger adults (range 22-35 yrs) with 20/25 VA or better were tested with dilated pupils in a modified Humphrey Field Analyzer, after 30 min of dark adaptation. Light sensitivity for 1.7° targets of either 450nm or ≥605nm was measured at 4, 7, 32, and 38° both nasally and temporally along the horizontal meridian. Test-retest reliability was good (r = .68, p<.0063). Lens density was estimated using Sample's technique. Results. Older adults exhibited on average a 0.6 log unit decrease in sensitivity for the 450nm target even with lens density taken into account (p<0001). Control comparisons against the >605nm target indicated that these threshold measurements were rod-mediated. Sensitivity variations as a function of eccentricity and nasal/temporal hemifield were both unaffected by aging. Conclusions. Older adults in good eye health experience decreased rod-system sensitivity. This deficit seems to be topographically generalized since it is not eccentricity dependent. Anatomical studies on rod density in donor retinas from old adults indicate an area of heightened rod loss in the peri-macula. This regional variation in rod loss is not reflected in the scotopic sensitivity of older adults in good eye health.
