Botulinum toxin: a novel treatment for pediatric cyclic esotropia.

Cyclic esotropia is a rare entity in which an esotropia presents in a regular 48-96 hour cycle, typically described as a 24-hour period of orthotropia followed by a 24-hour period of esotropia. The underlying mechanism of this phenomenon is unknown. Treatment usually involves surgical correction of the manifest strabismus. We report the case of a 3-year-old girl whose cyclic esotropia was broken following injection of botulinum toxin to both medial rectus muscles. She has remained constantly esophoric for 1 year.