The trend of myopia in children and its low age is a major social and public health problem in China. More seriously, retinopathy associated with high myopia has become the number one cause of irreversible blinding eye disease in adults in some parts of China. Physiological hyperopia has a protective effect on preventing the onset of myopia, and is one of the strongest predictors of myopia on its own, which is significant in curbing myopia from occurring at a younger age and preventing the development of high myopia before adulthood. However, it is not yet known how the physiological hyperopia changes in childhood, the stage at which the critical inflection point occurs, which key factors lead to the rapid fading of the physiological hyperopia and progression to myopia, and the strength of its effect. In the early stage of the study, the research group established a prospective cohort of preschoolers based on natural population sampling, which included a total of 2109 preschoolers aged 3-6 years from 22 kindergartens in a district in Beijing, and completed a 2-year follow-up, obtaining exploratory results on the changing pattern of physiological hyperopia and key influencing factors in younger children. The group will add new samples to the existing whole cohort sampling cohort and adopt the design scheme of prospective nested case-control study to determine the changing trend of fading trajectory of physiological hyperopia in school-age children, key inflection points and key risk factors, so as to provide new techniques for the prevention and control of childhood myopia.

Inclusion Criteria:

1. Children aged 6-9 years old, male or female;
2. Good cooperation in examination;
3. Parents cooperate and sign the informed consent form;

Exclusion Criteria:

1. Children with a history of drug allergy;
2. Pediatric patients with heart disease, cranial trauma or epilepsy, Down syndrome, or glaucoma will be excluded from the cohort.

The research group has already sampled 3-6 years old preschool children from 22 kindergartens in Haidian District, Beijing, and included them in the baseline cohort, which has been followed up continuously for 3 years. The research group will continue to add new samples to the existing cluster sampling cohort and reorganize the cohort of children aged 6-9 years old to conduct this study.