M Schneck, G Haegerstrom-Portnoy, J Brabyn
Smith-Kettlewell Eye Research Institute, RERC, San Francisco, United States
Which aspects of vision function show the earliest changes among the elderly and which show the greatest amounts of decline among the very old? A broad battery of simple, efficient vision tests and visual task performance measures were administered to a random sample of 900 community-living elderly in Marin County, CA near San Francisco. The mean age was 75.5 years with a range of 58-102 years. Testing was binocular with habitual correction. To enable comparison among measures having different units, a scale was developed "number of times worse than young normal". For each 5-year age interval of the sample, median value of the number of times worse than young was computed. As measured, using large red targets, temporal sensitivity shows no decline, even among the oldest. High contrast acuity declines only by a factor of 2, low contrast acuity and color discrimination by less than a factor of 4, and contrast sensitivity and SKILL Card (low contrast at low luminance) acuity a factor of 5. Stereopsis, attentional field size, retinal photostress and disability glare decline much more, with low contrast acuity in glare being 18 times worse than young normal in the oldest age group. Though standard high contrast acuity is well maintained even into very old age, other measures reveal significant decline. The dramatic changes in disability glare, retinal photostress, and attentional field size reflect changes in optical media, retinal integrity and cognitive function, respectively. Interestingly, optical media changes (as opposed to cortical changes) account for most of the loss of stereopsis. Significant associations were seen between vision measures and reading, face recognition and search. Measures other than standard acuity are required to reveal the extent of vision loss with age and to account for the alterations in performance
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