The Latest in Red Light Therapy

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June 2, 2025

By Dr. Dzung Tran, Australian College of Optometry (ACO)

Repeated low-level red-light (RLRL) therapy is a promising strategy for myopia control, with study results comparable to more established modalities such as orthokeratology and low-dose atropine.^1,2 RLRL therapy is based on the principle that increased light exposure can slow myopia progression, with the aim to deliver these effects through a concentrated, artificial source over short durations, rather than extended outdoor time.

A Look at Current Research

Research has been centered around the use of RLRL therapy combined with single vision correction, compared to standalone single vision correction. Studies have demonstrated statistically significant changes including reduced progression of axial length and myopic refraction. In a multicenter randomized controlled trial (RCT), findings showed a 69.4% reduction in axial length (AL) progression with the use of RLRL at 12 months.³

More recently, strong efficacy has been observed with the use of RLRL in high myopia. One study enrolled participants with spherical equivalent refraction (SER) beyond -4.00D and demonstrated that after 12 months, mean change in AL was -0.06mm in the RLRL therapy group and 0.34mm in the control group. Mean SER change was 0.11D and -0.75D in the RLRL and control groups, respectively.⁴

Another 12-month RCT evaluated children with SER beyond -6.00D and found that the changes in AL and SER for the RLRL group were -0.11mm and 0.18D, whereas the control group showed changes of 0.32mm and -0.80D respectively.⁵

Interestingly, these studies were able to demonstrate a shortening of AL and hyperopic shifts in SER for children with moderate to high myopia. The mechanism behind this is still unclear. It is hypothesized that the use of RLRL may enhance choroidal blood perfusion, which will in turn reduce scleral hypoxia and increase scleral collagen levels. There are studies which have shown an increase in choroidal thickness with the use of RLRL.⁶ However, this particular anatomical change does not exclusively explain the AL reduction.

The Potential for Pre-myopia Treatment

We have also gained some insight on the use of RLRL in children with pre-myopia and whether its use can delay the onset of myopia. 

One study defined pre-myopia as SER +0.50D to -0.50D and having one parent with ≤-3.00D. Results showed myopia incidence at 12 months to be 40.8% in the RLRL group and 61.3% in the control group. This represents a relative reduction in incidence of 33.4%. AL and SER progression also slowed in the RLRL group compared to the control group.⁷

Combination Therapy and RLRL

RLRL in combination therapy is a new area of investigation that is showing promising results in children who may otherwise continue to progress on monotherapy. 

One study included 8-13-year-old children who exhibited axial length growth of 0.5mm per year despite currently undergoing orthokeratology. They were randomized into combination therapy with RLRL (n=30) or to continue with OrthoK alone (n=17). The children were obviously aware which group they were in, but those taking measurements were masked. After 12 months, the mean AL changes were -0.02mm and 0.27mm in the combination therapy group and the OrthoK group, respectively.⁸

Another study also demonstrated AL shortening in RLRL-OrthoK combination therapy. This study had a poorer design, being retrospective and unmasked (both of which can introduce bias), but included 100 children. Like Xiong et al. (2024), it included children with poor responses to OrthoK alone, defined as axial elongation of 0.3mm or greater after one year of use. Those who chose to receive RLRL in addition to OrthoK for another 12 months (n=55) showed a mean AL change of -0.10mm, compared to those who chose to continue with OrthoK alone (n=45) who showed another 0.3mm increase.⁹

A 12-month retrospective cohort study compared the use of defocused incorporated multiple segments (DIMS) spectacle lenses alone, to RLRL alone, to combination therapy of RLRL and DIMS. Results showed a yearly axial change of 0.16mm for the DIMS spectacle lenses, -0.04mm for standalone RLRL and -0.13mm for combination therapy.¹⁰

Safety of RLRL

A recent systematic review of the safety of RLRL was performed, analyzing 20 past studies from its inception in 2021 until February 2024. The review demonstrated that the most common side effects were afterimages, lasting for a mean of 3.2 minutes. No irreversible vision loss or structural damage were reported in any of the studies.¹¹

However, it is worth noting that one study found that two red light devices exceed safety limits, potentially increasing the risk of photochemical and thermal changes.¹² Another study used adaptive optics scanning laser ophthalmoscopy to assess 99 children and demonstrated lower paracentral foveal cone density amongst RLRL users. Notably, one participant also showed small cystoid cavities within the ganglion cell layer, which completely resolved upon discontinuation of RLRL therapy.¹³ The longer-term effects of RLRL therapy are unknown.

Given uncertainties in the risks (whether the adaptive optics scanning laser ophthalmoscopy findings are meaningful, and what the long-term effects might be), the risk-benefit analysis of RLRL therapy should likely reside with individual families and their eye care practitioners at this stage. The ability of RLRL therapy to reduce myopic progression bestows a likely benefit. The effect in pre-myopia is also a possible benefit. The short-term changes measured with adaptive optics, and unknown longer-term effects, bestow an unknown risk.

Conclusion

RLRL provides practitioners with an additional tool to address the rapid global rise of myopia. 

So far, RLRL has shown to be effective and safe amongst users with minimal reported adverse effects. While available studies have been primarily based in China, trials have also been conducted in other countries including Australia, Spain and Japan. Again, children have been treated for over a year with no adverse events reported. However, RLRL is still a relatively new form of myopia control, and unknowns such as cellular-level and long-term effects need further investigation.

 

Dzung Tran is a clinical optometrist and educator at ACO Eye Health in Melbourne, Australia. She has a keen interest in pediatric optometry with a particular focus on myopia control. She is deeply committed to public health, providing essential eye care services to refugees and underserved communities. Dzung has also contributed internationally, working in Vietnam to deliver lectures and hands-on tutorials for optometry students, helping to support the next generation of eye care professionals.

 

References

1. Xiong F, Mao T, Liao H, et al. Orthokeratology and Low-Intensity Laser Therapy for Slowing the Progression of Myopia in Children. Biomed Res Int 2021;2021:8915867.
2. Chen Y, Xiong R, Chen X, et al. Efficacy Comparison of Repeated Low-Level Red Light and Low-Dose Atropine for Myopia Control: A Randomized Controlled Trial. Transl Vis Sci Technol 2022;11(10):33.
3. Jiang Y, Zhu Z, Tan X, et al. Effect of Repeated Low-Level Red-Light Therapy for Myopia Control in Children: A Multicenter Randomized Controlled Trial. Ophthalmology 2022;129(5):509-19.
4. Xu Y, Cui L, Kong M, et al. Repeated Low-Level Red Light Therapy for Myopia Control in High Myopia Children and Adolescents: A Randomized Clinical Trial. Ophthalmology 2024;131(11):1314-23.
5. Liu G, Liu L, Rong H, et al. Axial Shortening Effects of Repeated Low-level Red-light Therapy in Children With High Myopia: A Multicenter Randomized Controlled Trial. Am J Ophthalmol 2025;270:203-15.
6. Liu Z, Sun Z, Du B, et al. The Effects of Repeated Low-Level Red-Light Therapy on the Structure and Vasculature of the Choroid and Retina in Children with Premyopia. Ophthalmol Ther 2024;13(3):739-59.
7. Liu G, Rong H, Liu Y, et al. Effectiveness of repeated low-level red light in myopia prevention and myopia control. Br J Ophthalmol 2024;108(9):1299-305.
8. Xiong R, Wang W, Tang X, et al. Myopia Control Effect of Repeated Low-Level Red-Light Therapy Combined with Orthokeratology: A Multicenter Randomized Controlled Trial. Ophthalmology 2024;131(11):1304-13.
9. Yu M, Tang X, Jiang J, et al. Axial Length Shortening after Combined Repeated Low-Level Red-Light Therapy in Poor Responders of Orthokeratology in Myopic Children. J Ophthalmol 2024;2024:4133686.
10. Yang Y, Liu S, Gao W, et al. Synergistic effect of defocus incorporated multiple segment glasses and repeated low level red light therapy against myopia progression. Sci Rep 2025;15(1):3996.
11. Chen Y, Xiong R, Yang S, et al. Safety of repeated low-level red-light therapy for myopia: A systematic review. Asia Pac J Ophthalmol 2024;13(6):100124.
12. Ostrin LA, Schill AW. Red light instruments for myopia exceed safety limits. Ophthalmic Physiol Opt 2024;44(2):241-8.
13. Liao X, Yu J, Fan Y, et al. Cone Density Changes After Repeated Low-Level Red Light Treatment in Children With Myopia. JAMA Ophthalmol 2025.