Effectiveness and Safety of Red and Violet Light Therapy for Myopia Management

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February 1, 2024

By Michael Morton, BOptom

Repeated low-level red-light treatment may reduce myopia progression in refraction and axial length without significant adverse events. However, the evidence was low certainty, and the rebound effect seemed large after discontinuation. 

Increased time spent outdoors in bright light has been established as an effective protective factor for myopia prevention.¹ Recently, as an alternative to increasing bright light exposure, red light delivered on the retina at a much shorter duration of exposure has been studied for myopia control. From these studies, repeated low-level red-light (RLRL) therapy has emerged as a novel myopia control treatment modality. 

What Does the Treatment Involve?
A desktop light therapy device that emits a 650 nm red light laser is used for treatment. Treatment is under parental supervision for a maximum duration of three minutes, twice daily, with a minimum four-hour gap, five days a week. A web-linked system monitors compliance and ensures adherence to this specific protocol. This device is similar to those approved and used widely for amblyopia treatment in China, where unpublished anecdotal findings observed stabilization of axial elongation in children. 

What Do Research Results Show So Far Around Slowing Myopia Progression?
A large multicenter study² in China with 264 children aged 8-13 years with myopia of -1.00D to -5.00D is the most robust study of RLRL therapy to date. After 12 months, the RLRL treatment group showed 66% less axial myopia progression than the control group. Also, axial length shortening was present in 20% of study participants after 12 months. The exact process behind this was unclear, although this may be partially due to the thickening of the choroid.³ 

In the second year of the study,⁴ the two-year treatment group showed 57% less axial length progression than the control group. 

Over the two-year period, axial elongation and refractive progression were reported as:  

• treatment group: (AL: 0.16 mm; SER: -0.31D) 
• control group: (AL: 0.64 mm; SER: -1.24D). 

Is There a Rebound Effect?
These results are not without caveats. A strong rebound effect was noted in the children who discontinued RLRL after one year, with 0.14mm more axial length growth compared to those who continued in single vision spectacles. 

Are Other Studies Available?
The efficacy of RLRL therapy has also been demonstrated in other studies.^5,6 A meta-analysis was also published in April 2023,⁷ which included eight studies from China that met the criteria. The researchers concluded that RLRL treatment may reduce myopia progression in refraction and axial length without significant adverse events. However, they stated that the evidence was low certainty, and the rebound effect seemed large after discontinuation. 

How Does the Treatment Work?
The mechanism of action of RLRL is not yet fully understood. Unpublished anecdotal findings from children who used the device for amblyopia have noted increased choroidal thickness and blood flow. Recent studies linking scleral hypoxia to myopia have led to theories that RLRL treatment could boost fundus blood flow and metabolism, potentially alleviating scleral hypoxia and normalizing collagen levels.² 

Is RLRL Therapy Safe?
The two-year study reported satisfactory user acceptability and no adverse events or structural or functional retinal damage. 

However, in May 2023, a study from China⁸ reported a 12-year-old girl’s reduced vision for two weeks following five months of RLRL therapy for myopia. She showed foveal damage and macula hypoautofluorescence without inflammation. Her vision partially recovered to 20/25 after stopping the therapy for three months. The authors suggested causes included the patient’s light sensitivity or excessive exposure to RLRL therapy. The case study highlights the necessity for continuous assessment of patient’s visual acuity and retinal health during treatment. 

Can RLRL Reduce the Onset of Myopia?
A 12-month randomized clinical trial was conducted in China with children with pre-myopia (defined as a refraction of -0.50D to +0.50D).⁹ Children in the intervention group received RLRL therapy similar to the guidelines above. For children in the intervention group who did not have treatment interruption secondary to the COVID-19 pandemic, there was a relative 54% reduction in the incidence of myopia. This suggests RLRL may reduce the onset of myopia, though further research is required to confirm these findings. 

What About Violet Light and Myopia Control?
A theory has been proposed that the lack of violet light indoors could be myopigenic and that increasing violet light exposure might prevent myopia.¹⁰ However, in the only clinical trial to date in humans,¹¹ the treatment effect of the violet light lenses proved to be small and not significant (reduction of axial elongation by around 20%). Further study is required. 

What Further Research is Required Around RLRL Therapy?
Further research, including larger, more rigorous randomized controlled trials (RCTs), is required to: 

• Explore the efficacy and safety of the RLRL therapy beyond two years and in children of other ethnicities. 
• Determine the optimal treatment protocol for RLRL therapy for efficacy and safety, including identifying and reducing long-term rebound effects. 
• Determine the mechanism of action of RLRL therapy. 

 

Michael Morton is an optometrist and learning consultant with over 20 years of experience in eye care and eye health projects worldwide. He has developed both online and face-to-face training and learning tools for optometrists and other audiences and has worked in the field of global eye health, focusing on data, statistics, and advocacy. He was the lead learning designer and developer for the first e-learning courses in myopia management.

 

 

References 

1. French AN, Ashby RS, Morgan IG, Rose KA. Time outdoors and the prevention of myopia. Experimental eye research. 2013 Sep 1;114:58-68. 
2. Jiang Y, Zhu Z, Tan X, Kong X, Zhong H, Zhang J, Xiong R, Yuan Y, Zeng J, Morgan IG, He M. Effect of repeated low-level red-light therapy for myopia control in children: a multicenter randomized controlled trial. Ophthalmology. 2022 May 1;129(5):509-19. 
3. Wang W, Jiang Y, Zhu Z, Zhang S, Xuan M, Tan X, Kong X, Zhong H, Bulloch G, Xiong R, Yuan Y. Axial Shortening in Myopic Children after Repeated Low-Level Red-Light Therapy: Post Hoc Analysis of a Randomized Trial. Ophthalmology and Therapy. 2023 Apr;12(2):1223-37. 
4. Xiong R, Zhu Z, Jiang Y, Kong X, Zhang J, Wang W, Kiburg K, Yuan Y, Chen Y, Zhang S, Xuan M. Sustained and rebound effect of repeated low‐level red‐light therapy on myopia control: A 2‐year post‐trial follow‐up study. Clinical & Experimental Ophthalmology. 2022 Dec;50(9):1013-24. 
5. Zhou L, Xing C, Qiang W, Hua C, Tong L. Low‐intensity, long‐wavelength red light slows the progression of myopia in children: an Eastern China‐based cohort. Ophthalmic and Physiological Optics. 2022 Mar;42(2):335-44. 
6. Xiong F, Mao T, Liao H, Hu X, Shang L, Yu L, Lin N, Huang L, Yi Y, Zhou R, Zhou X. Orthokeratology and low-intensity laser therapy for slowing the progression of myopia in children. BioMed Research International. 2021 Jan 28;2021. 
7. Tang J, Liao Y, Yan N, Dereje SB, Wang J, Luo Y, Wang Y, Zhou W, Wang X, Wang W. Efficacy of repeated low-level red-light therapy for slowing the progression of childhood myopia: A systematic review and meta-analysis. American Journal of Ophthalmology. 2023 Apr 7. 
8. Liu H, Yang Y, Guo J, Peng J, Zhao P. Retinal Damage After Repeated Low-level Red-Light Laser Exposure. JAMA ophthalmology. 2023 May 25. 
9. He X, Wang J, Zhu Z, Xiang K, Zhang X, Zhang B, Chen J, Yang J, Du L, Niu C, Leng M. Effect of Repeated Low-level Red Light on Myopia Prevention Among Children in China With Premyopia: A Randomized Clinical Trial. JAMA Network Open. 2023 Apr 3;6(4):e239612-. 
10. Kawashima M, Jiang X, Kondo S, Miyauchi M, Miwa Y. Violet light exposure can be a preventive strategy against myopia progression. EBioMedicine. 2017 Feb 1;15:210-9. 
11. Mori K, Torii H, Hara Y, et al. Effect of violet light- transmitting eyeglasses on axial elongation in myopic children: A randomized controlled trial. J Clin Med. 2021;10:5462.