Distribution of the Electric Potential around the Orbit caused by Eye Deviation

Pseudo-eye-movement weves, or PEWs, which represent false eye movements on electronystagmograms in the horizontal eye lead during vertical rotation of the eye or in the vertical eye lead during horizontal eye rotation, cause some difficulties in clinical practice. This electronystagmographic study is aimed to find a way to cope with PEWs and to clarify their nature. Twelve electrodes were attached to 12 points of the face, and one electrode was placed on a mastoid process. The electric potential at each point was measured monopolarly or bipolarly by a topography system (NEC San-ei, Japan) during both horizontal and vertical alternating gaze. 1) Eye movements were successfully recorded from all 12 points. The maximum amplitude was seen in a pair of horizontal eye leads during horizontal eye movements and in a pair of vertical eye leads during vertical eye movements. 2) Horizontal and vertical PEWs disappeared or were reduced in amplitude when the electrodes at the inner canthus, nasal and lower margin of the orbit were shifted slightly lower than their conventional points. 3) A PEW is assumed to appear when the potential difference between a pair of conventional horizontal or vertical electrodes is not zero, during vertical and horizontal eye movements, respectively.