Patients with a variety of oculomotor and visual problems were evaluated by clinical examination and high resolution eye movement recordings. Patients with cortical and cerebellar disease were evaluated for amount and type of clinical abnormality. Their eye movements in response to visual stimuli were tested using paradigms devised to test the various oculomotor sub-systems, which were correlated with the clinical findings. Patients with cerebellar deficits showed the expected saccadic dysmetria to visual targets and low gain pursuit. In addition, preliminary data suggest that some cerebellar patients cannot change the gain of their saccades. Visual motion processing by normal subjects was evaluated using paradigms that tested the subjects' ability to predict future target motion in the generation of saccadic and smooth pursuit eye movements. Smooth pursuit in humans was found to be primarily based on prediction of future target motion and not on negative feedback to reduce retinal slip. A number of patients with unilateral cerebral hemispheric lesions showed pursuit deficits but had normal saccades to moving targets, suggesting that their lesions were not those of visual motion processing but actually of motor control.
