To investigate the prevalence of amblyogenic risk factors in the primary family members (parents, siblings) of patients with exotropia.

The authors of the present study examined primary family members including parents and siblings of 58 exotropia patients in our clinic. Best corrected visual acuity, refractive error, and cover-uncover test were performed. A total of 49 normal children's family members (control group) were examined in a similar manner. The prevalence of significant ocular findings were determined and compared to the control group.

In 58 eligible families (153 subjects except proband), 65.4% had significant ocular findings: In parents, anisometopia, astigmatism, hyperopia, and strabismus were found at a rate of 18.1%, 31.1%, 2.5%, and 11.2%, respectively. In siblings, anisometropia, astigmatism, hyperopia, and strabismus were found at a rate of 24.3%, 24.3%, 5.4%, and 18.9%, respectively. Compared to the control group, in parents of exotropia patients, anisometropia, astigmastim, and strabismus were observed at a higher rate. In siblings, anisometropia, and strabismus were observed at a higher rate.

Primary family members of exotropia patients have a high prevalence of amblyogenic risk factors. The present study offers rationale for providing comprehensive eye exams for parents and children with a family history of exotropia.