Myopia has become one of the leading causes of visual impairment globally and brings a heavy burden on the society. Therefore, preventing and controlling the progression of myopia has become an urgent public health issue that needs to be addressed.

The purpose of this study is to provide real-world evidence for identifying the incidence of myopia control (axial length growth rate ≤ 0.1mm/year) after 36-month RLRL therapy, and long-term safety of RLRL therapy in children and adolescents.

The prevalence of myopia in children is increasing worldwide and is viewed as a major public health concern. The current methods for myopia control include medication (e.g., atropine eye drops), optical (e.g., orthokeratology) and environmental interventions (e.g., time outdoors). Nevertheless, these treatments still have limitations. For example, low-concentration atropine may cause systemic side effects and accommodation loss caused by ciliary muscle paralysis. Moreover, the use of orthokeratology in children poses problems such as difficulty wearing, low compliance, and possible complications such as severe corneal infections. Thus, developing the more effective and safe treatment for myopia control in children and adolescents is the future research direction.

Recently, repeated low-level red-light (RLRL) therapy has emerged as a treatment for myopia control in children and adolescents, with promising efficacy and safety. It is suggested that continued RLRL therapy sustained promising efficacy and safety in slowing myopia progression within 2 years. However, relevant information on the effectiveness and safety of RLRL therapy on myopia control over 2 years among children and adolescents remain scarce, which deserves to be further explored.

In this multicenter observational study, the investigators aim to recruit 360 children aged 7-18 years who have currently accepted RLRL therapy at 3 study centers in China. All participants are randomly selected by stratified sampling based on the treatment duration of RLRL therapy (6-12 months, 12-24 months, 24-36 months, 36 months or more). First, the investigators will confirm whether these participants have pre-treatment data (before starting RLRL therapy), including visual acuity, axial length and cycloplegic refraction. Then all the eligible participants who meet the preliminary inclusion criteria, will be invited to come to the corresponding hospitals and further undergo the comprehensive ophthalmic examinations, including visual acuity, measurement of ocular biometric parameters, cycloplegic refraction, slit-lamp examination, color fundus photography, optical coherence tomography (OCT), electroretinography (ERG) and questionnaire surveys.

Inclusion Criteria:

1. Aged 7-18 years old
2. Myopia of cycloplegic spherical equivalent refraction (SER) of -1.0D or greater in both of eyes before starting RLRL therapy
3. Participants undergo RLRL therapy currently
4. With complete examination data before starting RLRL therapy, including visual acuity, axial length and cycloplegic spherical equivalence refraction
5. The subject and their guardian voluntarily sign the informed consent form

Exclusion Criteria:

1. Presence of strabismus, binocular vision abnormalities, other ocular abnormalities in either eye
2. Secondary myopia (such as myopia caused by retinopathy of prematurity or other eye diseases in infancy or early childhood) or myopia associated with systemic syndromes (such as Marfan syndrome)
3. Presence of other significant ocular and/or systemic diseases or abnormalities
4. Medical history of previous eye surgery, laser treatment, or intravitreal injection and so on
5. Participants if investigators believe they have contraindications that make them unsuitable for participation.

In this study, the investigators aim to recruit 360 participants aged 7-18 years at 3 study centers from 3 tertiary hospitals in China, stratified by the treatment duration of RLRL therapy including 6 to 12 months (<12 months); 12 to 24 months (< 24 months); 24 to 36 months (< 36 months); and 36 months or more. Thirty participants are recruited at each treatment duration for each study center. Therefore, the minimum number of subjects per study center is 30, and the maximum number of subjects per study center is 120.

Data will be shared as open data after proper anonymization.