Repeated Low-Level Red-Light Therapy for Shortening Axial Length

Inclusion Criteria: 1. Provision of consent. 2. Age: ≥ 6 and ≤ 16 years at enrolment. 3. High myopia: cycloplegic sphere ≤ -6.00 diopters (D) in both eyes. 4. Willing and able to participate in all required activities of the study. 5. The children currently on myopia control treatment can be recruited if myopia control treatments (including but not limited to atropine, orthokeratology, rigid gas-permeable lenses, defocus spectacles, etc.) are discontinued for at least 2 weeks. 6. Normal fundus, tessellated fundus or with peripapillary diffuse chorioretinal atrophy. Exclusion Criteria: 1. Secondary myopia, such as a history of retinopathy of prematurity or neonatal problems, or syndromic myopia with a known genetic disease or connective tissue disorders, such as Stickler or Marfan syndrome. 2. Pathologic myopia with signs of macula-involving diffuse chorioretinal atrophy, patchy chorioretinal atrophy, macular atrophy, lacquer cracks, myopic choroidal neovascularization or Fuchs' spots. 3. Strabismus and binocular vision abnormalities in either eye. 4. Previous any intraocular surgery affecting refractive status. 5. Other reasons, including but not limited to ocular or other systemic abnormalities, that the physician may consider inappropriate for enrolment.