Purpose: To assess the impact of severity of parental myopia on myopia in Chinese children.
Methods: Children aged 12 to 15 years were identified from a population-based sample in Guangzhou. Children's myopia was defined as a spherical equivalent refraction of ≤0.5 D based on cycloplegic (1% cyclopentolate) autorefraction. Using a questionnaire reported by the parents, the parental myopia was confirmed and the severity of myopia on the right eyes was classified into mild (<3.0 D myopia), moderate (3.0 to 6.0 D myopia), and high (>6.0 D myopia) myopia.
Results: Information was available for 1567 children aged 12 to 15 years. Analysis was restricted to children with no myopia in one parent and no, mild, moderate, or high myopia in the other. The prevalence of myopia in children was 53.5, 65.1, 76.3, and 80.6% when the severity of myopia in the second parent was no, mild, moderate, and high, and the prevalence of high myopia (spherical equivalent >6.0 D myopia) in children was 1.4, 2.9, 8.5, and 16.1% in the corresponding groups of parental myopia severity. Of the children with high myopia, 45.3% had parents with no reported myopia.
Conclusions: More severe myopia in one parent results in an increased risk of myopia in the children. However, most highly myopic children did not have a highly myopic parent and also half did not have any reported parental myopia. This suggests that while genetic factors contribute to the development of more severe myopia, environmental factors also contribute to high myopia in children in Guangzhou.