Evaluation of vertical deviations secondary to anatomical abnormalities.

Vertical strabismus secondary to anatomical abnormalities includes orbital anomalies leading to rotation of the extraocular muscle cone, converting the horizontal rectus muscles from adductors and abductors to elevators and depressors. Craniofacial syndromes also may include anomalous or absent muscles, simulating paretic strabismus. Abnormal musculature is also a cause of vertical strabismus. Included in this category is Brown syndrome and Duane retraction syndrome. Unusual strabismus that does not fit known patterns may be caused by anatomical anomalies. High axial myopia can lead to the "heavy eye syndrome" in which elevation is progressively more limited. Anti-elevation syndrome is caused by previous strabismus surgery, causing a Brown syndrome-like clinical picture with additional pseudo-overaction of the contralateral inferior oblique. Imaging studies are useful in determining the etiology of atypical strabismus and developing a treatment plan.