Horizontal saccade dynamics across the human life span

PURPOSE. To investigate saccade dynamics as a function of age to determine whether they follow the pattern of development and decline predicted by Weale's model of aging. METHODS. One hundred ninety-five participants between the ages of 3 and 86 years made visually guided horizontal prosac-cades ranging in size from 1 degrees to 60 degrees in response to dot stimuli. Eye movements were recorded binocularly with a video-based eye tracker, sampling at 120 Hz. Saccadic latency, accuracy, and velocity were measured and analyzed as a function of age. RESULTS. Mean saccadic latency decreased from 439 Ins at 3 years to 172 Ins at 14 years, followed by a period of relative stability to age 50 and finally, gradually increased to 264 Ins at :80 years. For saccadic accuracy (amplitude gain), there was a statistically significant (P < 0.05) interaction between sac-cade size and age. Participants made increasingly hypometric saccades as age and saccade size increased. Average age group saccadic asymptotic peak velocity (V-max) increased during childhood from 446 deg/s at age 3, to a peak of 610 deg/s at 14 years and then gradually declined with age to approximately 345 deg/s for participants >= 80 years. CONCLUSIONS. Age affected saccadic latency, accuracy, and velocity. For each parameter there was a different pattern of development and decline probably related to the way in which the portion of the brain that controls each function develops and ages.