Purpose 

This case report presents the diagnosis and management of an adult patient with cyclic esotropia, a rare and poorly understood form of strabismus, that is characterized by alternating periods of manifest strabismus and orthotropia. Few cases of adult-onset cyclic strabismus have been reported. The etiology, pathogenesis, and treatment for this condition are reviewed.

Case Report 

A 37-year-old man with high unilateral myopia and anisometropic amblyopia in his left eye developed cyclic esotropia 2 months after a scleral buckle procedure for a retinal detachment. A 48-hour cycle that consisted of a 24-hour period of orthotropia followed by a 24-hour period of constant left esotropia was present. Magnetic resonance imaging, electromyography, electroencephalography, and ocular and orbital echography were unremarkable, as was a neurological assessment that included fatigue and edrophonium testing. The patient was successfully managed with muscle surgery.

Conclusions 

The etiology and pathogenesis of adult-onset cyclic esotropia remain unknown. Cyclic esotropia should be considered in the differential diagnosis when an individual presents with a history of intermittent strabismus that is present some days and not others.