Effect of aging on smooth pursuit eye movement

Examination of smooth pursuit eye movement is useful for detecting central nervous system disorders. It is important to take patient's age into consideration when evaluating smooth pursuit eye movement. The purpose of the present study was to clarify the effect of aging on smooth pursuit eye movement. Thirty healthy volunteers (three groups of 10 volunteers, in their fifties, sixties, and seventies and over, respectively) served as subjects, and 10 healthy young volunteers (23 to 33 years old: mean age 26) served as controls. The pursuit target was driven by sinusoidal waveform with various amplitudes and frequencies. Target peak velocities ranged from 12.6 to 94.2 degrees/s. Eye movement signals were recorded d.c. EOG and pursuit gain (ratio of eye peak velocity to target peak velocity) was measured by a computer. Pursuit gain decreased with increasing target frequency and velocity in all age groups. This tendency was more remarkable in the older groups than in the young controls; in particular, it was more frequently seen at a frequency of 0.5 Hz. On the other hand, there was no significant relationship between pursuit gain and the target amplitude. In the group in their seventies and over, pursuit gain was saturated at about 60 degrees/s.