Duane retraction syndrome.

Duane retraction syndrome (DRS) consists of deficient horizontal eye movements, eyelid retraction, palpebral fissure narrowing, and abnormal vertical eye movements. Most cases are sporadic and unilateral (usually left side) with a slight female predominance. Several associated ocular and systemic conditions have been described in DRS patients. In most cases, the abducens nucleus and nerve are absent or hypoplastic, and the lateral rectus muscle is innervated by a branch of the oculomotor nerve. However, there may be contributing mechanical abnormalities. Type I DRS (primary gaze position esotropia with limitation of abduction) comprises the majority of cases. Approximately 50% of type I DRS patients are orthophoric in primary gaze. Esotropia is the most common type of strabismus encountered, and characteristic up shoots and down shoots occur in adduction. Surgical intervention has gradually become more popular in order to improve the primary gaze alignment and mitigate some of the associated abnormalities in ocular motility. However, patients are rarely rendered clinically normal, and limited expectations are appropriate.