Dissociation of the eyes in saccadic movement.

In horizontal saccades, abduction and adduction are not conjugate. Abduction starts shortly before adduction and reaches the turning point shortly after abduction. The duration in binocular recording is much shorter than in monocular recordings. The abducting eye has a tendency to move gradually on the new target. The adducting eye has, on the contrary, a tendency to overshoot. The characteristics of quick phases of horizontal optokinetic nystagmus, in which both eyes jump disconjugately to the new target, are similar to those of horizontal saccades. The main cause of this disparity may be a difference in neural mechanisms between abduction and adduction. Vertical saccades are not disconjugate.