Repeated Low-Level Red-Light Therapy Shortens Axial Length

Study Overview
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Brief Summary
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The purpose of this clinical trial is to investigate the incidence and magnitude of axial length shortening after repeated low-level red-light therapy in high myopia children and teenagers.

Detailed Description
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High myopia has become a major public concern globally, which is characterized by excessive axial elongation of the eyeball. Axial elongation is accompanied by mechanical stretching and thinning of the choroid and sclera, causing vision-threatening complications. Repeated low-level red-light (RLRL) therapy is an emerging effective and safe therapy for myopia control. Previous clinical trials in China have observed clinically significant axial shortening after RLRL treatment. The purpose of this study is to investigate and identify possible mechanism for axial length (AL) shortening after 12-month RLRL therapy in highly myopic children and teenagers aged 8-18 years. In addition to single vision spectacles, subjects will receive RLRL treatment at home under supervision of the parents/guardians according to a standard protocol. Axial length, visual acuity, cycloplegic spherical equivalent refraction, slit lamp, fundus camera and optical coherence tomography/angiography will be measured at 1-, 3-, 6- and 12-month follow-up visits.

Official Title
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Repeated Low-level Red-light Therapy in High Myopia Children and Teenagers: a Prospective Single-arm Study

Conditions
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High Myopia, Axial Length, Eye Diseases

Intervention / Treatment
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* Device: RLRL


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Provision of consent. Age: ≥ 8 and ≤ 18 years at enrolment. High myopia: cycloplegic sphere of -6.00 diopters (D) or greater in both eyes. Willing and able to participate in all required activities of the study. 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. Normal fundus, tessellated fundus or with peripapillary diffuse chorioretinal atrophy. Exclusion Criteria: 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. Pathologic myopia with signs of macula-involving diffuse chorioretinal atrophy, patchy chorioretinal atrophy, macular atrophy, lacquer cracks, myopic choroidal neovascularization or Fuchs' spots. Strabismus and binocular vision abnormalities in either eye. Previous any intraocular surgery affecting refractive status. Other reasons, including but not limited to ocular or other systemic abnormalities, that the physician may consider inappropriate for enrolment.

Ages Eligible for Study
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Minimum Age: 8 Years
Maximum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Repeated low-level red-light (RLRL) therapy<br>single vision spectacles & RLRL | Device: RLRL<br>* RLRL will be performed twice per day with an interval of at least 4 hours, each treatment last 3 minutes, in addition to single vision spectacles with power for correcting distance refraction.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence rate of axial length shortening greater than 0.05 mm | Incidence rate of axial length shortening > 0.05 mm is characterized as the ratio of the number of participants whose axial length has shortened by greater than 0.05 mm to the total number of participants. Axial length (mm) is measured using the IOL Master. | 12 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence rates of axial length reduction greater than 0.10 mm and 0.20 mm | Incidence rates of axial length shortening > 0.10 mm and 0.20 mm are characterized as the ratio of the number of participants whose axial length has shortened by greater than 0.10 mm and 0.20 mm to the total number of participants. Axial length (mm) is measured using the IOL Master. | 12 months | 
| Magnitude of axial length shortening among shortened eyes | The magnitude of axial length shortening is characterized as the amount of axial length reduction in eyes with axial shortening. Axial length (mm) is measured using the IOL Master. | 12 months | 
| Changes in choroidal thickness (μm) | Changes in choroidal thickness are characterized as the difference between each follow-up visit and corresponding baseline values which are measured using the optical coherence tomography. | 1, 3, 6 and 12 months | 
| Changes in axial length (mm) | Changes of axial length is characterized as the difference between each follow-up visit and baseline values which are measured using the IOL Master. | 1, 3, 6 and 12 months | 
| Changes in corneal curvature (mm) | Changes of corneal curvature is characterized as the difference between each follow-up visit and baseline values which are measured using the IOL Master. | 1, 3, 6 and 12 months | 
| Changes in anterior chamber depth (mm) | Changes of anterior chamber depth is characterized as the difference between each follow-up visit and baseline values which are measured using the IOL Master. | 1, 3, 6 and 12 months | 
| Changes in white to white (mm) | Changes of white to white is characterized as the difference between each follow-up visit and baseline values which are measured using the IOL Master. | 1, 3, 6 and 12 months | 
| Change of cycloplegic spherical equivalent refraction | Cycloplegic spherical equivalent change (Diopter, D) is characterized as the difference between each follow-up visit and baseline values. Refraction with full cycloplegia is performed with an autorefractor. The data on spherical and cylindrical power and axis is automatically extracted from the autorefractor. The spherical equivalent power (D) is calculated as the spherical power (D) plus half of the cylindrical power (D). | 1, 3, 6 and 12 months | 
| Change of pathologic myopia fundus META-PM grading | The fundus images are classified based on META-PM classification system. Color fundus images are obtained using the fundus camera. | 1, 3, 6 and 12 months | 
| Change in best corrected visual acuity | Best corrected visual acuity change is characterized as the difference between each follow-up visit and baseline values. Visual acuity is assessed using an Early Treatment Diabetic Retinopathy Study (ETDRS) chart with standard illumination at a distance of 4 meters. | 1, 3, 6 and 12 months | 
| Incidence of self-reported adverse events | Incidence of self-reported adverse events is the rate of self-reported adverse events over a specified period for all the subjects. Subjects are asked to report any treatment-emergent adverse events, including but not limited to glare, flash blindness, and afterimages. | 1, 3, 6 and 12 months |