A Case of Cyclic Esotropia Cured by Botulinum Toxin Injection

ABSTRACT

Cyclic strabismus is a rare entity, which is characterized by alternating periods of strabismus and orthophoria.The mechanism is not clear but seems to be related to the biological clock. Cyclic esotropia is the most common type. On "strabismic"days,a large-angle esotropia will appear, and the binocular vision is impaired. On "straight"days, orthophoria or microstrabismus will appear and no abnor-mal binocular vision is observed. As a treatment, surgery based on the full amount of heterotropia on the strabismic day,has been successful, but treatment by chemodenervation ith botulinum toxin has not been reported yet. Authors experienced the cyclic esotropia following head trauma by a traffic accident in a 3-year-old boy and tried the injection of botulinum toxin on both medial rectus muscles as a treatment. In one-year follow-up observation, the cyclic pattern and esodeviation has disappeared.