Vertical strabismus

Vertical strabismus refers to a condition where the eyes are not aligned at the same height, resulting in an upward or downward deviation. In most cases, it is non-comitant, meaning the angle of deviation varies with different gaze directions and distances. It is often accompanied by paralysis or overaction of one or more vertical muscles (eye movements are a coordinated effort of all extraocular muscles; when vertical muscles overact, their strength increases, enhancing their effect on vertical eye movements). The main symptom is that the visual axes of the two eyes are not on the same horizontal plane, with one eye higher than the other. It often manifests as compensatory head postures such as torticollis, face turn, chin elevation, or chin depression.