To explore the influence of regional light climate levels (light levels) on myopia in children and adolescents and the differences among different populations.

Two kindergartens, two primary schools and two junior high schools were randomly selected from each of the 187 districts (counties) in Sichuan Province. In each school, students (at least 80 students) were selected from the entire class of each grade for vision examination, and questionnaires were conducted among primary school students in grades 4 to 6. The χ² test was used for the differential comparison of myopia rates. The logistic regression model was used to study the influence of regional light climate levels on myopia.

A total of 330 132 students were included. Among them, 5.9% were from Category II areas (45>Eq≥40klx）, 9.8% from Category III areas (40>Eq≥35klx）,15.1% from Category IV areas (35>Eq≥30klx), and 69.2% from Category V areas (Eq<30klx). The myopia rates of children and adolescents in Class II, Class III, Class IV and Class V areas were 30.4%, 29.0%, 33.9% and 43.1%, and increased with the decrease of light climate levels (the increase of type codes). After controlling for covariates, with the type II area (high light level) as the reference, the risk effect of myopia was observed in the type III, type IV, and type V areas (OR=1.433, 95% CI:1.331-1.543; OR=1.543, 95% CI: 1.437-1.656; OR=1.325, 95% CI: 1.238-1.418, all P<0.001). Stratified analysis showed that the same effect was observed in both male and female students, as well as in regions with good and poor economic levels (P<0.001).

The level of natural light in a region may affect the prevalence of myopia among children and adolescents.It is recommended to ensure adequate light intensity in reading and writing environments, provide supplementary artificial lighting when necessary, and further increase the duration of outdoor activities.