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 prosaccades 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 ms at 3 years to 172 ms at 14 years, followed by a period of relative stability to age 50 and finally, gradually increased to 264 ms at >or=80 years. For saccadic accuracy (amplitude gain), there was a statistically significant (P<0.05) interaction between saccade size and age. Participants made increasingly hypometric saccades as age and saccade size increased. Average age group saccadic asymptotic peak velocity (Vmax) 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>or=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.