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 meet the standards with which investigators and study physicians think it is not appropriate to enroll.