Figure 3. Prevalence of Refractive Error for Primary School Students Aged 6 to 13 Years During the 6 Years of Screenings.

The prevalence of mild myopia increased in 2020 compared with previous years in children aged 6 to 8 years. Mild myopia: −3 diopters (D) < spherical equivalent refraction (SER) ≤ −0.5 D; moderate myopia: −6 D < SER ≤ −3 D; high myopia: SER ≤ −6 D; and no myopia: SER > −0.5 D.