Introduction: Cyclic strabismus is a rare disorder in which manifest strabismus and controlled latent deviation (heterophoria) alternates on a regular pattern which is usually over a 48-hr period. During the "straight" period the patient has a fully controlled heterophoria for all distances, with very good fusion and stereopsis. During the "squinting" period the patient has a constant manifest strabismus for all distances, with no demonstrable fusion and stereopsis.
Method: We describe 2 cases of alternate day exotropia. One patient requires strabismus surgery to obtain constant binocularity. The second patient underwent surgery for an intermittent exotropia and subsequently developed an alternate day exotropia. The condition very gradually reduced over the years and the patient is now fully binocular.
Conclusion: We report the first 2 cases of cyclic exotropia in non-Japanese female children presenting from about 1 to 3 years of age, without ocular or systemic pathology.