Effect of visual impairment on neuropsychological test performance.

Three vision-dependent neuropsychological tests of visual processing--Benton's Facial Recognition (FR), Judgment of Line Orientation (JLO), and Visual Form Discrimination (VFD)--were administered to subjects on the same day as routine ophthalmic examination. Seventeen subjects had Jaeger near vision of J5 (analogous to 20/50) or worse resulting from refractive error, while 13 control subjects had normal near vision of J1. Neuropsychological test scores of these groups were compared with each other and also the published standardization group for each test. Low near-vision subjects' performances on FR and VFD were significantly poorer than both control group subjects and standardization group subjects, but performance on JLO was not significantly altered. These results demonstrate that visual impairment can result in unexpectedly low scores on certain tests of visual processing, which suggests that poor vision might also affect results of other neuropsychological tests that involve vision, such as tests of visual processing and tests which use vision as a vehicle to deliver test stimuli to the relevant portions of the cortex. We therefore strongly urge examiners to secure control over potential bias resulting from reduced vision by instituting routine near visual acuity testing of all subjects prior to or during neuropsychological assessment.