Fig. 1. Electro-oculogram (EOG) schematic. The eye can be considered a dipole with the anterior part relatively more positive than the posterior pole. EOG electrodes have been fixed to the outer and inner canthi of the left eye. On the left side of the diagram as the eye moves to the left, the outer canthal electrode (being closer to the positive pole of the eye) becomes more positive than the inner canthal electrode. Such a change in potential can then be recorded on a voltage meter. When the eye turns to the right, the inner canthal electrode then becomes positive and again a change in potential can be recorded but with opposite polarity. (Carr RE, Siegel IM: Visual Electrodiagnostic Testing. Baltimore: Williams & Wilkins, 1982)