BACKGROUND: Although the prevalence of phoria in adults is well documented, data are scarce on phoria in children. We present results using modified clinical technique vision screening and data from the Orinda Longitudinal Study of Myopia on a large, population-based sample of nonstrabismic children to document the prevalence of phoria with age. METHODS: We collected cross-sectional (N = 1495) and longitudinal (N = 469) data. Phoria data were collected by cover tests administered by one observer who subjectively classified phoria as orthophoria, esophoria, or exophoria in 2 delta steps. RESULTS: Ninety-seven percent of the children were orthophoric at distance, and there were no significant changes with age. Near phoria showed a more normal distribution, with a 10.8% decrease in the prevalence of exophoria (from 31.8 to 21.0%) and a 5.5% increase in the prevalence of esophoria (from 6.7 to 12.2%) between kindergarten and fifth grade. CONCLUSIONS: Children are typically orthophoric or exophoric at near, but convergent shifts occur with age.
BACKGROUND: Although the prevalence of phoria in adults is well documented, data are scarce on phoria in children. We present results using modified clinical technique vision screening and data from the Orinda Longitudinal Study of Myopia on a large, population-based sample of nonstrabismic children to document the prevalence of phoria with age. METHODS: We collected cross-sectional (N = 1495) and longitudinal (N = 469) data. Phoria data were collected by cover tests administered by one observer who subjectively classified phoria as orthophoria, esophoria, or exophoria in 2 delta steps. RESULTS: Ninety-seven percent of the children were orthophoric at distance, and there were no significant changes with age. Near phoria showed a more normal distribution, with a 10.8% decrease in the prevalence of exophoria (from 31.8 to 21.0%) and a 5.5% increase in the prevalence of esophoria (from 6.7 to 12.2%) between kindergarten and fifth grade. CONCLUSIONS:Children are typically orthophoric or exophoric at near, but convergent shifts occur with age.