Prevalence of heterophoria in a population of school children in central China: the Anyang Childhood Eye Study

AIM: To investigate the prevalence of heterophoria and the relationship between heterophoria and refractive error in a school-based study conducted in central China. METHODS: A total of 2363 7th-grade children were recruited into the cross-sectional school-based Anyang Childhood Eye Study (ACES) by cluster sampling method. Heterophoria was examined using alternate cover and cover-uncover testing. The Maddox rod and prism test were conducted at...