Predicting declines in vision and vision performance in older individuals

Abstract

The purpose of this study was to determine whether measures other than high contrast acuity can predict significant future reductions in high contrast acuity and reading performance (Pepper Test). The SKI study collected longitudinal data on a vision test and visual performance battery in a random sample of elderly residents of Marin County. Average age was 73.8 at the first test and 78.2 years at the second. Only those with high contrast acuity of 20/40 or better (90%, N=537) at the first test are considered here (median acuity = 20/20−1 (logMAR 0.04)). The criterion for significant future acuity loss was 0.3 log units (doubling of visual angle) per decade and the criterion for corrected reading rate loss was 60 words/minute per decade. Twenty-one percent of this group showed subsequent significant acuity loss. Several other spatial vision tests were significant predictors of acuity loss (acuity in glare, low contrast low luminance (SKILL Dark) acuity, contrast sensitivity), as was stereopsis (Frisby Stereo Test). A deficit in any one of the spatial vision variables and in stereoacuity of 0.3 log unit increases the risk of future acuity loss 2.5 times. Both contrast sensitivity and SKILL Dark acuity were significant predictors of declines in reading performance, but stepwise logistic regression revealed that low contrast, low luminance acuity had a higher independent association with reading. Multivariate regression analysis results showed that age, SKILL Dark acuity and corrected reading rate at baseline were all significant predictors of future decreased reading rate. Each 0.3 log unit decrement in SKILL Dark acuity increased the odds of a significant loss in corrected reading rate by a factor of 3.2. These findings highlight the importance of vision measures other than standard acuity for assessing older adults. Such tests can predict visual disability and loss of driving privileges.