Nystagmus is very noticeable but ra

Nystagmus is very noticeable but rarely recognized.
Nystagmus can be clinically investigated by using a number of non-invasive standard tests. The simplest one is the caloric reflex test, in which one external auditory meatus is irrigated with warm or cold water or air. The temperature gradient provokes the stimulation of the horizontal semicircular canal and the consequent nystagmus.

The resulting movement of the eyes may be recorded and quantified by special devices called electronystagmograph (ENG), a form of electrooculography (an electrical method of measuring eye movements using external electrodes),[6] or even less invasive devices called videonystagmograph (VNG),[7] a form of video-oculography (VOG) (a video-based method of measuring eye movements using external small cameras built into head masks) by an audiologist. Special swinging chairs with electrical controls can be used to induce rotatory nystagmus.[8]

Over the past forty years objective eye movement recording techniques have been applied to the study of nystagmus, and the results have led to a greater accuracy and understanding of the condition.