Head Position-Dependent Changes in Ocular Torsion in Skew Deviation

Skew deviation is a vertical strabismus that is often associated with abnormal ocular torsion and head tilt. It has been attributed to imbalance of vestibulo-ocular reflex (VOR) projections from the utricles in the inner ears to ocular motoneurons, but direct evidence is lacking. The utricles lie roughly in the horizontal plane, and they normally detect static positions (tilts) of the head. We postulate that if skew deviation is caused by imbalance of the utriculo-ocular reflex, the abnormal torsion might be head position-dependent.