Females who go through puberty at a younger age may have a higher risk of myopia. Photo: nrd on Unsplash. Click image to enlarge.

Adolescent myopia has been positively associated with the onset of puberty, and Chinese researchers believe this association may help explain the higher myopia prevalence in females in the country. They noted that this could be explained by the differences in physiological and behavioral changes during puberty between genders.

In a nationwide cross-sectional study, data came from five national surveys in China, including 338,896 boys aged 11 to 18 and 439,481 girls aged nine to 18. Myopia was defined according to unaided distance visual acuity and subjective refraction, and puberty status was defined dichotomously as menarche or spermarche, the milestones of sexual maturity.

The researchers found that menarche was associated with a 7% higher risk of myopia among girls but that the association between spermarche and myopia in boys was smaller and nonsignificant. The sex disparity in myopia was consistent across seven- to 18-year-olds in all five surveys. Post-menarche girls and post-spermarche boys showed a 29% to 41% and 8% to 19% higher risk of myopia than pre-menarche girls and pre-spermarche boys, respectively.

Over 16% of the sex disparity in myopia could be explained by earlier onset of puberty in females, compared with almost 11% explained by several other behavioral factors together.

The study authors noted that going through puberty at a younger age puts females at an increased risk of developing higher-grade myopia earlier and therefore increase their risk of developing secondary ocular pathology. “For these reasons, early interventions for preventing myopia onset might be more important in girls,” they wrote. “Because our study did not analyze refraction and axial length data, it remains unclear whether earlier puberty could lead to a higher degree of myopia in girls.”

They believe that detailing the public health implications of this finding requires further longitudinal studies with more accurate measures of myopia and puberty status.