THE APPLICATION OF SMOOTH-PURSUIT EYE-MOVEMENT ANALYSIS TO CLINICAL MEDICINE

Pursuit tracking eye movements were analyzed from selected patients wi th neurological injuries and compared to the responses of 20 normal su bjects. The patients/subjects tracked a small spot of light moving sin usoidally in the horizontal plane at a frequency of 0.4 Hz and a peak to peak amplitude of 40 degrees. Eye-movement responses were separated into a smooth-pursuit component and a saccadic component. The smooth- pursuit component was analysed by calculating the gain, phase, and asy mmetry. The saccadic component was quantified by calculating the perce ntage of the total tracking movement contributed by the saccadic syste m. The patients with smooth-pursuit impairment exhibited a higher perc entage of saccadic tracking and a lower smooth pursuit gain compared t o the normal subjects. One patient with a unilateral lesion exhibited significant asymmetry in the smooth-pursuit component. In this case, t he direction of the asymmetry indicated the side of the lesion.