The cerebellum is known to be very important for the maintenance of body balance or of smooth eye movements. Eye movements consist of two factors, that is saccade and pursuit, which are examined using the stimuli of saw-toothed waves. A round target of 1 cm in diameter moves from the right to the left side with a visual angle of 30° for the period of 3 sec and it moves back to the right side immediately after the target has reached to the left side. This reversed stimulus is also used. The saccade and pursuit eye movements were evoked in the examinees who followed the traget movements, which were recorded by an electronystagmography (ENG). The eye velocity of saccade and the latency between the initiation of the target and that of eye movements were measured. Horizontal eye movements, saccade and pursuit were studied.
The numbers of small saccadic eye movements during the pursuit eye movements were measured. In 20 normal adults, the eye velocity of saccade was 169±19°/sec, the latency 0.15 ±0.05 sec and the small saccadic eye movements 0-1 beats/cycle during the pursuit eye movements.
In 27 cerebellar lesions, the eye velocity of saccade was within normal limits, the latency prolonged and the pursuit eye movements strongly impaired. That is, the pursuit eye movements seem to be closely related with the cerebellum.
