Purpose: To determine the relationship between myopia in parents and their children in a sample of urban Chinese children.
Methods: Random sampling was used to identify a population-based sample of 4364 children aged 5 to 15 years from Guangzhou. Children had a comprehensive ocular examination including cycloplegic (1% cyclopentolate) refraction (ARK-30; Nidek Corp.). Data on parental myopia, education levels, incomes and occupations, and children's near-work activities were collected by questionnaire. Myopia in the children was defined as a spherical equivalent refraction of ≤-0.5 diopter.
Results: The prevalence of myopia was significantly higher in the children than in their parents (78.4% in 15-year-old children, compared with 19.8% in the parents, p < 0.001). The prevalence of myopia was 88.9% in children with one parent myopic, 83.3% in those with two parents myopic, and 68.2% in those without myopic parents, compared with 85.3% in those with tertiary-educated parents, 73.3% in those with secondary-educated parents, and 60.0% in those with less educated parents. Parental income and occupation had weaker associations with childhood myopia. In multiple regression analysis, only parental myopia remained significantly associated with myopia in the children. The observed additional risk among those with more myopic parents could not be attributed to reported near-work activities in children.
Conclusions: A high percentage of children in Guangzhou become myopic by the age of 15, irrespective of the myopic status of their parents. There is, however, an additional risk of myopia in children with myopic parents, which may have a genetic basis, but further analysis of the impact of possible environmental confounders is required.