The Effects of Different Outdoor Light Exposure Modes on Retinal Blood Flow

Study Overview
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Brief Summary
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In 2020, the overall myopia rate among children and adolescents in my country was 52.7%. The COVID-19 pandemic has increased students' time of indoor eye-using, and it showed that the light exposure intensity of myopic students is lower than that of non-myopia students. Studies have found that the light wave bandwidth has a significant impact on the emmetropization of the eye, and white light can promote emmetropia more than monochromatic light. It shows that outdoor exercise has a protective effect on the occurrence and development of myopia in children and adolescents, but the specific mechanism is still unclear. Retinal blood flow is sensitive to myopic stimuli, and is a short-term indicator of the relationship between light environment and myopia. This study selected retinal blood flow as the primary outcome, aiming to compare the effects of different outdoor light exposure modes on retinal blood flow after 1 hour of intense eye use, and provide clues for the prevention and control of myopia.

Detailed Description
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In 2018, eight departments including the Ministry of Education jointly issued the Implementation Plan for Comprehensive Prevention and Control of Myopia in Children and Adolescents. As of 2020, the overall myopia rate among children and adolescents in my country was 52.7%. The COVID-19 pandemic has increased students' time of indoor eye-using, and it showed that the light exposure intensity of myopic students is lower than that of non-myopia students. Studies have found that the light wave bandwidth has a significant impact on the emmetropization of the eye, and white light can promote emmetropia more than monochromatic light. It shows that outdoor exercise has a protective effect on the occurrence and development of myopia in children and adolescents, but the specific mechanism is still unclear. Retinal blood flow is sensitive to myopic stimuli, and is a short-term indicator of the relationship between light environment and myopia. Also, there is a theory that reduced choroidal blood flow causes scleral hypoxia, which leads to the development of myopia. Therefore, this study selected retinal blood flow as the primary outcome, aiming to compare the effects of different outdoor light exposure modes on retinal blood flow after 1 hour of intense eye use, and provide clues for the prevention and control of myopia.

Official Title
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The Effects of Different Outdoor Light Exposure Modes on Retinal Blood Flow in School Students: a Randomized Controlled Trial

Conditions
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Myopia

Intervention / Treatment
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* Behavioral: Weak outdoor light
* Behavioral: Strong outdoor light


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: School students aged from 7 to 15, regardless of sex or gender; Diopter between -2.0D and 3.0D, and astigmatism not exceed 0.75D; No organic disease and in good general condition; Have obtained the consent of their parents or guardians, and can cooperate. Exclusion Criteria: Suffering from amblyopia, strabismus, color weakness, congenital cataract, glaucoma and other eye diseases; Other circumstances judged by the investigator to be unsuitable to participate in the research.

Ages Eligible for Study
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Minimum Age: 7 Years
Maximum Age: 15 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: The participants were randomly divided into the following two groups: 4000Lux natural light exposure; 10000Lux natural light exposure.
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Weak outdoor light<br>4000Lux natural light exposure | Behavioral: Weak outdoor light<br>* Stay and stare far on the balcony or under the tree<br>|
| Experimental: Strong outdoor light<br>10000Lux natural light exposure | Behavioral: Strong outdoor light<br>* Stay and stare far in the sunlight<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Retinal blood flow density after relaxing for 15 minutes | Data collected from Optovue AngioVue OCT (macular blood data collected) for the dominant eye. The duration of relaxing was recorded by a timer. | Exposing to sunlight for 15 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Retinal blood flow density changes between relaxing for 5 and 15 minutes | The difference in retinal blood flow density was calculated between 5 and 15 minutes. | Retinal blood flow density after relaxing for 5 and 15 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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myopia, retinal blood flow, accommodative micro-fluctuation, outdoor light exposure