School-based Myopia Prevention Trial for Children With Adequate Hyperopic Reserve

Inclusion Criteria: * Students in grades 1 to 4 from participating schools. * Non-myopic children with adequate hyperopic reserve at baseline, defined as cycloplegic spherical equivalent refraction in the worse eye within the following age-specific reference ranges: +1.72 D to +2.45 D at age 6 years; +1.48 D to +2.00 D at age 7 years; +1.19 D to +1.79 D at age 8 years; +1.11 D to +1.38 D at age 9 years; +0.92 D to +1.16 D at age 10 years; and +0.83 D to +1.07 D at age 11 years. * Written informed consent provided by a parent or legal guardian, with assent obtained from the child when appropriate. Exclusion Criteria: * Strabismus, amblyopia, or other ocular abnormalities. * Systemic disease or other medical conditions that may affect study participation. * Has received any myopia prevention intervention in the past 3 months. * Any other condition judged by the study doctors to make participation inappropriate.