Study: Myopia Epidemic in China Doubles in One Generation

A new long-term study—tracking children and their parents has found a dramatic intergenerational shift in the prevalence and severity of myopia in China, strongly implicating environmental factors over genetics in driving the “myopia boom.” [1]

Researchers enrolled 686 children (aged 7-15 at baseline) in the the Guangzhou Twin Eye Study and followed them annually from 2006 to 2018, measuring cycloplegic refractions and biometric data. At the same time, non-cycloplegic refractions and biometry were assessed in their parents. 

By young adulthood, 78% of these children were myopic, compared to 42.1% in their parents’ generation. The prevalence of high myopia (-6 D or more) rose to 9.6% vs 5.2% in parents, and moderate myopia (-3 to -6 D) increased to 38.8% (vs 9.9%). Meanwhile, the proportions of mild hyperopia and emmetropia steadily declined in the younger generation. 

Interestingly, extreme myopia (≤ -9.0 D) and severe hyperopia (≥ +2.0 D) did not show significant intergenerational change. 

The investigators determined that much of the refractive shift was due to increased axial length in the children relative to their parents. Other biometric parameters—lens power, corneal curvature, corneal power—exhibited little generational change. They also noted a difference in the distribution of refractions: the children’s refraction curve was broadly “flattened” across -6.0 D to -0.5 D, rather than the narrower peak seen in their parents around -1.0 D. 

If genetics were the primary driver, one might expect a strong correlation between a parent’s position in the refractive distribution and their offspring’s, the authors noted, but the study found only a low correlation coefficient (~0.30) between the percentile positions of parents vs children, suggesting that environmental factors have overridden familial inheritance in shaping refractive outcomes.

The authors say that the magnitude and speed of change—essentially doubling myopia prevalence in one generation—are incompatible with shifts in genetic background, which evolve much more slowly. Instead, they point to social environment changes: greater educational pressure, prolonged near work, diminished time outdoors, and urban lifestyle as prime suspects. 

Their supplemental questionnaires also documented differences in residential patterns, childhood outdoor time, and parental vs child educational attainment, further linking shifts in behavior and environment to the refractive changes observed.

The authors stated that further research is needed to identify which environmental interventions are most effective (e.g. school schedule changes vs outdoor breaks) and whether they can curb the upward trend in moderate and high myopia.

Reference

1. Chen X, Hu Y, Morgan I, et al. Intergenerational change in China’s epidemic of myopia: the impact of the social environment. British Journal of Ophthalmology 2025;109:1093-1098.