Stable ocular position in the dark in vestibular and cerebellar disease

Abstract

Eye movements and eye positions were monitored in the dark by dc-oculography in patients with spontaneous nystagmus due to peripheral vestibular disease and in patients with gaze-evoked nystagmus due to cerebellar lesions. During fixation of lateral target lights, change of eye position due to ongoing nystagmus was minimal in all patients. By comparison, during imaginative fixation in darkness fast phases of nystagmus occurred less regularly and at lower frequency; as a consequence the amount of eye drift was greater. However, despite a lack of visual stimulus and despite ongoing nystagmus, the average eye position in the dark was usually remarkably well preserved. Therefore, the fixation system is able to define an average eye position for the eye in the orbit during imaginative fixation in darkness.

Key Words:

• eye drift
• eye position
• vestibular and cerebellar disease