Effect of Different Intensities of Repeated Low-Level Red-Light Therapy on Choroidal and Retinal Blood Flow Among Adults

Study Overview
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Brief Summary
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The purpose of this clinical trial is to evaluate the effect of different intensities of repeated low-level red-light (RLRL) therapy on the choroidal and retinal blood flow among adults.

Detailed Description
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Repeated low-level red-light (RLRL) therapy is an emerging innovative and non-invasive treatment for a variety of eye diseases. Notably, RLRL was found to be effective in thickening choroidal thickness in a 1-year randomized controlled trial, indicating its potential in modulating blood flow in the fundus. However, it remains unclear how long it takes for the RLRL to make a difference in fundus blood flow and whether there is a dose-response. The purpose of this study is to evaluate the different intensities of RLRL on the choroidal and retinal blood flow among adults. This study will be conducted with a randomized cross-over design with a total follow-up of 3 months. The RLRL therapy will be carried out in the study site under supervision according to a standard protocol. Ophthalmic examinations, including visual acuity, intraocular pressure, optical coherence tomography, optical coherence tomography angiography, spherical equivalent refraction, slit lamp, and biometrics will be evaluated at enrollment and during follow-ups.

Official Title
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Effect of Different Intensities of Repeated Low-Level Red-Light Therapy on Choroidal and Retinal Blood Flow Among Adults

Conditions
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Choroid, Retina

Intervention / Treatment
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* Device: RLRL device


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged 18-40 years at enrolment. Healthy adults with best corrected visual acuity equal to or better than 1.0 in both eyes. No other ocular condition except for myopia. Provision of consent and able to participate in all required activities of the study. 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. Strabismus and vision abnormalities in either eye. Refractive media opacity: corneal opacities, cataracts, or implanted intraocular lens, etc. Ocular abnormalities that affect retinal function: macular degeneration, diabetic retinopathy, retinal detachment, glaucoma, or ocular hypertension, endophthalmitis, uveitis, optic neuropathy, etc. Previous history of refractive surgery, intraocular surgery, laser therapy, and intravitreal injection, etc. Systemic abnormalities: diabetes, hypertension, etc. Drugs therapies with toxicity effects on the retina: hydroxychloroquine, etc. Other contraindications, 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: 18 Years
Maximum Age: 40 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
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: RLRL of 50% intensity<br>Participants will be treated with RLRL (50% intensity) twice per weekday with an interval of at least 4 hours, each treatment last 3 minutes. Single-vision spectacles with power for correcting distance refraction will also be used if necessary. Cross over arms after one month of use and one month of washout period. | Device: RLRL device<br>* Crossover device (RLRL of 50% or 100% intensity - alternate to first group). Cross over arms after one month of use and one month of washout period.<br>|
| Active Comparator: RLRL of 100% intensity<br>Participants will be treated with RLRL (100% intensity) twice per weekday with an interval of at least 4 hours, each treatment last 3 minutes. Single-vision spectacles with power for correcting distance refraction will also be used if necessary. Cross over arms after one month of use and one month of washout period. | Device: RLRL device<br>* Crossover device (RLRL of 50% or 100% intensity - alternate to first group). Cross over arms after one month of use and one month of washout period.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes of macular choroidal thickness. | Changes in the macular choroidal thickness are characterized as the difference following 1 month with RLRL therapy relative to the baseline which is measured by optical coherence tomography. | 1 month | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in OCTA-derived parameters of choriocapillaris. | Changes in the choriocapillaris microvasculature are characterized as the difference following 1 month with RLRL therapy relative to the baseline which is measured by optical coherence tomography angiography | 1 month | 
| Changes in OCTA-derived parameters of retina. | Changes in retinal microvasculature are characterized as the difference following 1 month with RLRL therapy relative to the baseline which is measured by optical coherence tomography angiography. | 1 month | 
| Incidence of treatment-emergent adverse events | Incidence of treatment-emergent adverse events is the rate of treatment-emergent adverse events over a specified period for subjects in the intervention arm. Subjects are asked to report any treatment-emergent adverse events, including but not limited to glare, flash blindness, and afterimages. | 1 month | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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repeated low-level red light therapy, choroid, retina, optical coherence tomography, optical coherence tomography angiography