Abstract: Myopia before the age of 6 is defined as preschool myopia. It has a higher risk of developing high myopia and some secondary irreversible blinding complications. Compared with school-aged children (over 6 years old), preschool myopia is relatively less. Studies have reported that the prevalence of preschool myopia is 0.42%~11%. The prevalence of myopia varies widely among races, with non-Hispanic white children lower than Hispanic children and Asian American children and often higher in Asian children. Parental myopia is often thought to increase the likelihood of myopia in preschool children. Unlike school-age myopia, the prevalence of preschool myopia decreases with age, and there is no obvious difference between genders, but whether it is related to near work is still under discussion. (Int Rev Ophthalmol, 2022, 46: 216-221)

Key words: myopia, preschool myopia, school myopia, prevalence, related factor