To explore the effectiveness of using low-intensity single-wavelength red light to prevent myopia in schoolchildren, and to provide a feasible scheme for reducing the incidence of myopia.

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.