Red Light Therapy: Short-term Choroidal and Retinal Changes

The Short-term Impact of Different Types of Red Light Therapy on Choroid and Retina

This research project is a prospective, randomized controlled trial designed to assess the short-term effects of varied red light therapies on the choroidal and retinal structures in adult myopes. The primary objective is to determine which specific retinal regions or cells are primarily affected by short-term repeated low-level red-light (RLRL) therapy, potentially inducing choroidal thickening. The secondary objective is to assess the safety of different types of red light therapy in adult myopes.

The study will enroll 45 myopic adults aged 18-40 years old as participates. They will be randomly assigned into three RLRL groups: small circle (d=0.30mm), medium circle (d=0.50mm), and annular groups (an inner diameter of 0.50 mm and an outer diameter of 0.70mm) without disclosure of their specific group to maintain study blinding. The groups are differentiated by the size and shape of the light spots formed on the retina but with the same power (0.15 mW with a 4 mm pupil size). The Eyerising Myopia Management Device, modified for this study, will be used to administer RLRL with three different spot patterns, adhering to safety standards to minimize risk and ensure participant safety.

Before the treatment, baseline data will be collected from each participant. Baseline assessments will consist of demographics information, visual acuity checks, axial length measurements, subjective refraction, slit-lamp examinations, adaptive optics imaging, optical coherence tomography and angiography (OCT & OCTA), posterior blood flowgraphy, electroretinography (ERG), and the Flicker-plus test. Then participants will undergo daily treatments for 14 days, using the therapy settings of the group to which they have been assigned. The treatment will last for 3 minutes twice a day, with a minimal interval of 4 hours. During the 14-day study period, participants will undergo daily assessments by a series of ophthalmic examinations.

Outcomes measured will track changes in choroidal thickness, electrical activity of the retina, axial length, and best corrected visual acuity, alongside other image reports such as adaptive optics imaging, posterior blood flowgraphy and OCT & OCTA scans.

This study addresses the gaps in understanding how RLRL therapy affects myopia and aims to identify the retina's high-response areas to red light. By doing so, it hopes to minimize unnecessary exposure and potential damage, enhancing the safety and effectiveness of the therapy.

Study Overview

• Status: Recruiting
• Conditions: Myopia
• Intervention / Treatment: Device: Repeated Low-Level Red-Light

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Mingguang He; Phone Number: 85234002795; Email: mingguang.he@polyu.edu.hk
• Study Contact Backup: Name: Yanxian Chen; Phone Number: 85227666111; Email: yan-xian.chen@polyu.edu.hk

Study Locations

• Hong Kong
  • Hong Kong, Hong Kong
    • Recruiting
    • The Hong Kong Polytechnic University
    • Contact: Staff; Phone Number: 85227665111; Email: polyu@polyu.edu.hk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Age: 18 to 40 years.
2. Myopic spherical equivalent refraction (SER) between -1.00D to -6.00D in both eyes.
3. Best corrected visual acuity (BCVA): 20/20 or greater.
4. Informed consent for participation.

Exclusion Criteria:

1. Anisometropia greater than 1.50D.
2. Ophthalmic diseases other than refractive errors, including but not limited to strabismus and binocular vision abnormalities in either eye.
3. Systemic diseases (e.g., endocrine, cardiac diseases) and developmental abnormalities.
4. Inability to attend regular follow up assessment.
5. Undergo RLRL therapy in the past 6 months
6. Contraindications to RLRL therapy.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Standard group; 15 subjects will be recruited in the Standard group, where participants will use the current standard Repeated Low-Level Red-Light device.	Device: Repeated Low-Level Red-Light; All participants will receive a video guide of the Repeated Low-Level Red-Light device. Eligible subjects will receive daily treatment for 14 days, with each treatment lasting for 3 minutes twice a day, with a minimal interval of 4 hours.
Experimental: Other types of red light therapy group; These 45 subjects will be randomly assigned into three groups: small circle, medium circle, and annular red light groups without disclosure of their specific group to maintain study blinding.	Device: Repeated Low-Level Red-Light; All participants will receive a video guide of the Repeated Low-Level Red-Light device. Eligible subjects will receive daily treatment for 14 days, with each treatment lasting for 3 minutes twice a day, with a minimal interval of 4 hours.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in choroidal thickness measured by OCT	The change in choroidal thickness (ChT) after 14-day of repeated low-level red-light therapy in adult myopes. OCT and OCTA imaging will be performed using the ultra-wide field swept-source OCT/A system (VG200). The macula was scanned using the 12-line radial scan pattern with a resolution of 1024 × 12. Each image will cover an area of 12 × 9 mm centered on the fovea with an average of 4 consecutive scan overlaps. ChT is defined as the perpendicular distance between the outer choroid-sclera margin and the retinal pigment epithelium-Bruch's complex. The average ChT of the whole ETDRS 9 grid and central ChT (an area centered on the fovea with a diameter of 1 mm) was calculated with the built-in software. The VG200 device has been acquired by our team and is available for use.	Choroidal thickness will be measured every day from enrollment to the end of treatment at 2 weeks.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in electrical activity of the retina measured by ERG	A standard full-field ERG and mfREG will be conducted. The full-field ERG includes Dark-adapted 0.01 ERG, Dark-adapted 3.0 ERG, Light-adapted 3.0 ERG, and 30 Hz Flicker ERG. Prior to testing, patients will undergo appropriate dark adaptation for 20 minutes to ensure accurate results for the dark-adapted tests.	ERG will be carried out on the 7th and 14th days of the study
Change in axial length (AL) measured by IOL Master	IOL Master will be used to measure the AL of both eyes. Five measurements will be taken for each eye. The AL measurement will be based on the mean of these five values if the desired precision (≤0.05 mm) is achieved.	AL will be taken every day from enrollment to the end of treatment at 2 weeks.
Change in best corrected visual acuity (BCVA)	An Early Treatment Diabetic Retinopathy Study (ETDRS) chart (Precision Vision, Villa Park, Illinois, USA) with standard illumination will be used to measure distance visual acuity. Visual acuity measurement is performed at a distance of 4 meters. BCVA will be measured.	BCVA will be taken every day from enrollment to the end of treatment at 2 weeks.
Change in adaptive optics imaging	The adaptive optics retinal camera rtx1 system (Imagine Eyes) will be employed for high-resolution imaging of cones and rods cells.	Adaptive optics imaging assessment will be carried out on the 7th and 14th days of the study.
Change in optical coherence tomography angiography (OCTA) scan	OCT and OCTA imaging will be performed using the ultra-wide field swept-source OCT/A system (VG200). The macula was scanned using the 12-line radial scan pattern with a resolution of 1024 × 12. Each image will cover an area of 12 × 9 mm centered on the fovea with an average of 4 consecutive scan overlaps.	OCTA assessment will be taken every day from enrollment to the end of treatment at 2 weeks.
Change in posterior blood flowgraphy	The Laser Speckle Flowgraphy system (LSFG-NAVI) will be utilized to assess blood flow in the posterior segment of the eye. This method involves capturing and analyzing dynamic changes in speckle patterns created by laser light reflecting off moving blood cells, specifically targeting the retinal and choroidal blood flow. The LSFG-NAVI device has been acquired by our team and is available for use.	The posterior blood flowgraphy will be taken every day from enrollment to the end of treatment at 2 weeks.
Change in flicker-plus test	The Flicker-plus test, part of the AVOT system, quickly identifies losses in rod and cone photoreceptors without extensive dark adaptation by measuring flicker modulation thresholds (FMTs) at five key central vision points. Adaptation times are minimal-15 seconds for cones and 90 seconds for rods. The test protocol follows the methodologies established by Amithavikram et al.	Flicker-plus test will be carried out on the 7th and 14th days of the study

Collaborators and Investigators

• Sponsor: The Hong Kong Polytechnic University

Study record dates

Study Major Dates

• Study Start (Estimated): December 22, 2024
• Primary Completion (Estimated): September 30, 2025
• Study Completion (Estimated): September 30, 2025

Study Registration Dates

• First Submitted: November 19, 2024
• First Submitted That Met QC Criteria: December 22, 2024
• First Posted (Actual): March 25, 2025

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: December 22, 2024
• Last Verified: November 1, 2024

More Information

Terms related to this study

• Keywords: myopia; choroidal; retinal; red light therapy
• Additional Relevant MeSH Terms: Eye Diseases; Refractive Errors; Myopia
• Other Study ID Numbers: HSEARS20240715002

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No