FIG. 1.

Representative record of left eye position-in-space (gaze) during binocular visual fixation of a stationary target by a 68-year-man with 13-year duration, DOPA-responsive Parkinson's disease, with Hoehn-Yahr score of 2. Horizontal and vertical records have been offset to aid clarity of display. He had no observable head tremor and no ocular tremor is apparent on the record. The record was made using the magnetic-field/search-coil technique, with analog filtering of coil signals (bandwidth, 0–150 Hz) before digitization at 500 Hz. No digital filtering was used; details of this methodology have been described.^24,29