Research Review

Red Light Therapy for Myopia: Merits, Risks, and Questions

May 15, 2024

By Dwight Akerman, OD, MBA, FAAO, FBCLA, FIACLE

Photo Credit: Teodoro Guerrini, Getty Images

In their review article, noted myopia researchers Schaeffel and Wildsoet explore the potential of repeated low-level red light (RLRL) therapy as a novel approach to managing childhood myopia. Red light therapy, also known as repeated low-level red light (RLRL) therapy, involves foveal exposure to long wavelength (red) laser light (635–650 nm) for three minutes, twice a day. To date, more than 20 clinical studies have been conducted in China on this topic, with consistent results showing that the therapy slows the progression of myopia in children. The treatment has also been successful in delaying the onset of myopia in pre-myopic children. While there are differences in the study design, duration, and age of the participants among the studies, the consistent finding is that the treatment significantly slows the axial elongation rate, with some studies even showing regression.

RLRL treatment is minimally disruptive to the daily routines of the recipients, requiring them to look into the eyepieces of available devices for only three minutes twice a day. It is a non-invasive and non-pharmaceutical intervention, making it a desirable option for parents and children. However, before the treatment can be widely adopted, two main issues must be addressed: the long-term safety of the RLRL treatment and the mechanism underlying its treatment effect.

One concern is the long-term safety of the treatment, particularly in young children whose eyes are still developing. The exposure of young eyes to incident red light energy per retinal unit area may be much higher than generally assumed, and the long-term effects of this exposure are still unknown. Given the unresolved long-term safety issues for this therapy, there is an urgent need to review and revise safety monitoring strategies, with consideration given to the inclusion in all clinical trials of more sensitive tests, such as low-contrast visual acuity and high-resolution OCT retinal imaging.

The mechanism underlying the treatment effect of RLRL therapy is not fully understood. Some studies suggest that the therapy reduces the rate of eye elongation, which is a significant factor in the progression of myopia. Further research is needed to determine the exact mechanism underlying the treatment effect and to optimize the treatment’s efficacy. Puzzlingly, on termination of the RLRL therapy, myopia progression appears to rebound rapidly.

The authors state that eight critical questions related to RLRL therapy need to be addressed before its widespread adoption:

  1. Is coherent (laser) light more effective than incoherent (LED) light when irradiances are matched
  2. Do we need such intense, localized energy or would exposure to red room lighting be sufficient?
  3. How long must individual stimulation sessions be, how often should treatments be repeated within a day, and what is the optimal spacing?
  4. Can the effect be achieved without stimulating the fovea? Would a Maxwellian view also work?
  5. In relation to the underlying mechanisms, that is, whether the effect is visual or metabolic, must visible red light be used, or would near-infrared light also work?
  6. What is the mechanism driving this inhibitory eye growth response and if driven by a retinal signal, is there something special about stimulating the L/M cone system alone, with little input from the blue cone system, given that the generated red laser patch contains minimal spatial information that could be used to analyze the image?
  7. Why does RLRL therapy-induced choroidal thickening develop more slowly than reported for other myopia control interventions, yet is less enduring upon termination of this therapy?
  8. What is a suitable battery of appropriately sensitive techniques for monitoring visual function and retinal/ choroidal structure, as critical to establishing the shorter and long-term safety of the RLRL therapy?

In conclusion, red light therapy shows promise as a new intervention for myopia control. The therapy is minimally disruptive and has been shown to slow the progression of myopia in children. However, before the therapy can be widely adopted, the long-term safety of the treatment must be assessed, and the mechanism underlying the treatment effect needs to be better understood. Further research is required to optimize the therapy’s efficacy and determine whether it can be a viable myopia intervention for children in the long term.


Red Light Therapy for Myopia: Merits, Risks, and Questions

Frank Schaeffel, Christine F Wildsoet 

Recently published clinical studies in China have convincingly demonstrated that ‘repeated low-level red light’ (RLRL) therapy, involving foveal exposure to long wavelength (red) laser light (635–650 nm) for 3 min, twice a day, slows myopia progression in children. To date, more than 20 papers on this topic have been published. Premyopic children have also been treated, with the RLRL therapy successfully delaying the onset of myopia. While among published investigations, which included retrospective and randomized controlled clinical trials, there are important study design differences, including study duration (3 months to 2 years) and the age of participants (3–14 years), that the treatment significantly slowed the rate of eye elongation was a consistent finding, with axial lengths found to be shrinking in some studies. These biometric changes were coupled to the regression of myopia in the latter case and the slowed progression of myopia in the former. Transient choroidal thickening, of interest as a potential biomarker of treatment efficacy for myopia control interventions, has also been reported in some studies.

Given that the RLRL treatment is minimally disruptive to the daily routines of the recipients, typically young children, simply requiring them to look twice daily for very short (3 min) periods into the eyepieces of now widely available devices (particularly in China), why should it not be the myopia intervention of choice, when the resulting inhibitory effect on myopia progression surpasses the treatment effects of all other currently available myopia control interventions?  There are two main issues to consider: (A) The long-term safety of this RLRL treatment in which young eyes are regularly exposed to incident red light energy per retinal unit area, potentially much higher than generally assumed, and possibly extending over many years and (B) the mechanism underlying this treatment effect, which may include actual reductions in eye length.

Schaeffel, F., & Wildsoet, C. F. (2024). Red light therapy for myopia: Merits, risks, and questions. Ophthalmic and Physiological Optics. 02 April 2024. Online ahead of print.


To Top