Complex or Incomitant Strabismus

Abstract

Complex, incomitant strabismus may be defined as binocular misalignment that differs in magnitude in distinct directions of gaze. Etiologies include cranial nerve palsies (CN III, IV, and VI), dysinnervation syndromes (Duane and Moebius syndromes), restrictive processes (Graves' orbitopathy, Brown syndrome), and anatomic (fallen eye syndrome, craniofacial synostosis, blowout fractures). Myasthenia gravis can also present with incomitant strabismus. Obtaining a thorough past medical and surgical history, as well as a history of trauma is critical as is measuring the ductions, versions, and the magnitude of misalignment in each cardinal gaze as well as any ocular torsion. Armed with this information, the etiology can typically be determined. Forced ductions may provide additional clues to the cause and help direct treatment. There is typically more than one way to surgically reduce the various forms of incomitant strabismus, and these are discussed, but all approaches share the goal of creating, or restoring, of a wide field of binocular single vision and stereopsis while minimizing torticollis. Nonsurgical treatment with prisms, botox, or patching provides a practical alternative in some cases.