THE EFFECT OF PARENTAL HISTORY OF MYOPIA ON CHILDRENS EYE SIZE

Objective.-To evaluate whether eye size and shape are different in chi ldren based on their parental history of myopia. Design.-A community-b ased cohort study of schoolchildren (aged 6 to 14 years), the Orinda ( Calif) Longitudinal Study of Myopia. Setting.-Four campuses of the Ori nda Union School District, a predominantly white, high socioeconomic s tatus community. Participants.-A cross-sectional volunteer sample of 7 16 children (662 nonmyopic) in the first, third, and sixth grades in 1 989, 1990, and 1991. All children in those grades were eligible for in clusion in the study. Intervention(s).-None. Main Outcome Measures.-Re fractive error (measured by autorefraction), corneal curvature (measur ed by photokeratoscopy), crystalline lens power (measured by video pha kometry), and axial ocular dimensions (measured by ultrasonography). R esults.-With prevalent cases of myopia excluded and grade in school an d ''near work'' controlled for, children with two myopic parents had l onger eyes and less hyperopic refractive error (analysis of covariance , P less than or equal to.01) than children with only one myopic paren t or no myopic parents. A model incorporating parental history is only improved by the addition of near work for the prediction of refractiv e error. Conclusions.-Even before the onset of juvenile myopia, childr en of myopic parents have longer eyes. These results suggest that the premyopic eye in children with a family history of myopia already rese mbles the elongated eye present in myopia.