Red Light Intervention for Myopia Prevention

Inclusion Criteria: * Students of grade 1-4 in the participating schools; * Students' eyes have no myopia, that is the cycloplegic spherical equivalent（SE） \>-0.50D, and at least one eye accords with the pre-myopic state, that is -0.50D \<cycloplegic SE≤0.50D; * Students whose mother and/or father are in myopia status (SE \< -3.0D for either of eyes); * Students whose parents sign informed consent and agree to let their kids participate in baseline screen and follow-up examinations and surveys. Exclusion Criteria: * Students whose parents do not sign informed consent; * Students who have strabismus and/or other binocular vision abnormality; * Students who have other eye diseases and/or systematic diseases; * Students who have DC \<=-1.5D; * Students whose difference of SE between the two eyes \>=1.5D; * Students who meet the standards with which investigators and study physicians think it is not appropriate to enroll.