Conjugate gaze is the ability of the eyes to work together or in unison. It refers to the motion of both eyes in the same direction at the same time. The eyes can look laterally (left/right), upward, or downward. Disorders in conjugate gaze refer to the inability to look in a certain direction with both eyes.
Conjugate gaze is mediated in the brain stem by the medial longitudinal fasciculus, which is a nerve tract that connects the abducens, trochlear, and oculomotor nuclei. These nuclei, in turn, are responsible for the muscles that control eye movements. The left pontine center connects with the right frontal center for conjugate gaze to the left, and the right pontine center connects with the left frontal center for conjugate gaze to the right. If extraocular muscles are not working properly, dysconjugate gaze can result, which can then cause diplopia. The mechanisms for horizontal eye