Compensatory eye movement and gaze fixation during active head rotation in patients with labyrinthine disorders.
Compensatory eye movement and gaze fixation during active head rotation were studied in patients with unilateral and bilateral loss of vestibular function. Patients with bilateral lesions were asked to perform mental arithmetic tasks in the dark. Although compensatory eye movements of these patients corresponded to 38-46% of compensatory movements in normal subjects, the ability of patients with lesions to visually fix on a stationary target was markedly impaired. Visual fixation on moving targets attached to the head (head-fixed targets) was also measured and found to be good. For patients with unilateral lesions, in the early stages of the disease, findings during rotations to the intact side resembled those for normal subjects, while results of rotations to the affected side resembled those for patients with bilateral lesions.