1. A method of recording nystagmus (involuntary rhythmic movements of the eyes) activity by detecting the electrical activity of the extraocular muscles.
2. A method of assessing and recording eye movements by measuring the electric activity of the extraocular muscles.
3. The registering of eye movements in spontaneous and induced nystagmus, using either a bioelectric or a photoelectric technique.

The bioelectric method records the changes in electrical potential produced by movements of the eye in the plane of two electrodes placed on either side of the eye or, if vertical nystagmus is to be measured, then the two electrodes are positioned above and below the eye.

Its important clinical application is the testing of vestibular function or the sense of balance and spatial orientation.