Abstract
Purpose. To investigate possible vision factors that may impair performance on standardized cognitive tests routinely given to older adults during geriatric assessments. This paper evaluates the effect of varying levels of blur, pupil size, and contrast sensitivity on cognitive performance. Methods. Ninety young adults and 34 old adults were assessed on three vision-dependent neuropsychological tests requiring visual processing: Digit Symbol Test, Trail Making Part A and B, and Block Design. Subjects were randomly assigned to a control group, 20/20 visual acuity or one of two levels of simulated blur 20/50 or 20/100. Results. In the final analysis, pupil size and contrast sensitivity were covaried out as an influence on cognitive performance isolating the effects of blur and compared to performance influenced by pupil size, contrast sensitivity, and blur. Only young subjects' performance on Digit Symbol was negatively influenced by blur when the effects of pupil size and contrast sensitivity were excluded in the analysis. Old subjects were negatively affected by blur when visual acuity, pupil size, and contrast sensitivity were covaried out leaving only blur. Examining blur with contrast sensitivity in old subjects showed no effects. Only Block Design, designs 9 and 14 were negatively influenced by blur for the young when excluding the covarients of visual acuity, pupil size and contrast sensitivity. Discussion. These results demonstrate that older adults who have visually significant eye pathology (senile miosis, glaucoma, and cataracts) and/or refractive error may receive distorted visual input, altering test conditions and potentially negatively biasing neuropsychological test results.