Prevalence of and Early-Life Influences on Childhood Strabismus

BACKGROUND: Strabismus is a common disorder of largely unknown cause reported to occur more frequently in children with neurodevelopmental conditions and in children born prematurely or of low birth weight. Population-based investigation of other potential early-life influences has been limited. OBJECTIVE: To investigate the prevalence of and the early-life risk factors associated with childhood strabismus. DESIGN: Cross-sectional analytical study of a nationally representative sample of children participating in the Millennium Cohort Study. SETTING: United Kingdom. PARTICIPANTS: A population-based sample of 14 980 children aged 3 years. MAIN OUTCOME MEASURES: Parental report of "isolated" strabismus and "neurodevelopmental" strabismus (ie, in the context of neurologic disorders), considered separately. RESULTS: Three hundred forty-three children had strabismus (of whom 20 5.8% had neurodevelopmental/neurologic disorders), giving a total weighted prevalence of 2.1% (95% confidence interval, 1.8%-2.4%). In multivariable analysis, the risk of isolated strabismus was reduced in children of nonwhite maternal ethnicity and was increased in those born after an assisted or cesarean delivery and in those who were of low birth weight and preterm (in particular, late preterm). An increased risk of neurodevelopmental strabismus was independently associated with maternal smoking into later pregnancy, maternal illnesses in pregnancy, and decreasing birth weight for gestational age and sex. Socioeconomic status was associated with isolated (inverse relationship) and neurodevelopmental (U-shaped relationship) strabismus. CONCLUSIONS: Several early-life social and biological factors are associated with strabismus, with differences in patterns between isolated and neurodevelopmental forms. Further collaborative research could explore this hypothesis to identify modifiable risk factors.