AGE VARIATIONS IN NORMAL HUMAN CONTRAST SENSITIVITY

Abstract

The visual contrast sensitivity (the reciprocal of contrast threshold) was studied as a function of age. Psychophysical measurements of binocular and monocular contrast thresholds were made for 33 normal observers at spatial frequencies within the range 0.5 to 40 cycles/degree. The observers were divided into three different age groups: young, middle-aged, and old subjects with the age ranges 6--10 years, 20--40 years, and 60--70 years, respectively. All observers had healthy eyes, normal vision, and Snellen visual acuity of 1.0 or better in both eyes. In all groups, contrast sensitivity for binocular and monocular viewing peaked at a spatial frequency around 3--5 cycles/degree and showed the typical attenuation at low and high spatial frequencies. The binocular contrast sensitivity was higher than the monocular. There was no significant difference between young and middle-aged subjects with regard to contrast sensitivity. Subjects aged 60 years or more showed significantly lower contrast sensitivity than younger subjects for most spatial frequencies above 4 cycles/degree. We may thus conclude that both the binocular and monocular contrast sensitivity seemed independent of age within the range of 6 to 40 years. For higher ages studied (above 60 years), there was a loss of sensitivity in the middle and high frequency regions.