A longitudinal study of oculomotor function in normal older people

Cross-sectional studies have found declines in most measures of oculomotor function in older subjects compared to young controls, but no prior study has followed the same subjects over time. We measured saccade peak velocity, saccade delay time, smooth pursuit, optokinetic nystagmus (OKN), visual-vestibular-ocular-reflex (VVOR), fixation suppression of the vestibulo-ocular reflex (VOR-fix), and the vestibulo-ocular reflex in 53 subjects (older than 75 years) able to complete at least 9 yearly evaluations. In addition at each visit all patients underwent a complete history and examination, a gait and balance assessment, mini-mental status evaluation, and visual acuity testing. A subset of subjects completed 12 yearly evaluations (14 patients). Despite significant declines of most variables over time, smooth pursuit gain and saccade peak velocity remained stable during the duration of the study both in the 9-year group and the patients completing 12 years. Decline in OKN, VVOR, and VOR were significantly correlated (P < 0.001) with decline in the Tinetti gait and balance score, even after controlling for age. In normal healthy older subjects, smooth pursuit and saccade peak velocity are relatively maintained while OKN, VVOR, and VOR function decline. The significant correlation between decline in oculomotor measures and gait and balance measures (even after controlling for age) suggests a common mechanism for the decline in both measures.