Electrooculogram

The electrooculogram (EOG) is a technique for measuring the electrical potential difference between the front and back of the eye using surface electrodes placed around the eyes. This corneal-retinal potential (CRP) varies linearly with eye rotation along both horizontal and vertical axes within approximately 30 degrees of center, making EOG useful for tracking eye movement direction. In assistive technology, EOG-based eye trackers offer an alternative to camera-based systems for computer control by people with motor disabilities. EOG systems provide very fast response times (under 250ms) and work regardless of lighting conditions or eyelid position, but are prone to signal drift — a slowly changing baseline offset that degrades absolute position accuracy over time.