Nystagmus which results from gaze (i.e. extraocular motion) in a particular direction, is detected by asking the patient to look at a target object 20 to 30 degrees to the right or left of their midline (i.e. when looking straight ahead) for 20 seconds.
If gaze nystagmus is present, the eye will beat towards the intended direction of gaze.
The ability to maintain eccentric gaze is a function of the brainstem and midline cerebellum, particularly the vestibulocerebellum.
Gaze nystagmus is attributable to a central process, typically due to drugs (i.e. sedatives, anti-epileptics), alcohol, CNS tumors, or cerebellar degenerative syndromes.