The effect of aging on visual-vestibuloocular responses.

To determine age-related changes in oculomotor function we measured vestibuloocular (VOR), optokinetic (OKN), and visual-vestibular responses in a large group of normal subjects over the age of 75 years and compared the results with those from a group of young adults. Compared with the young subjects, older subjects had: (1) an amplitude-dependent decrease in VOR gain, (2) a shorter dominant VOR time constant, (3) a lower OKN slow-phase velocity saturation, and (4) a decreased ability to enhance and suppress the VOR with vision. These functional changes in older subjects are presumably secondary to well-documented, age-related changes in the sensory and neural elements of the visual-vestibulooculomotor pathways. They may be a contributory factor to the common complaints of dizziness and dysequilibrium in people over the age of 75 years.