Red Light Therapy For Eye Health [UPDATED]

When is the best time and where 

Disclaimer – the following information is for educational purposes only and Red Light Rising does not recommend using red light therapy on your eyes without first speaking to your eye specialist.

In this blog we are going to cover the latest study on red light therapy and eye health. Published the 24th of November in the prestigious journal, Nature.

• Introduction
• Study
• Results
• Conclusion 

Introduction

Metabolic rate and aging are both regulated by mitochondria, which are cell organelles present in all human cells.

Mitochondrial membrane potential, however, declines with age resulting in reduced adenosine triphosphate (ATP) production, which is a major source of cellular energy.

The retina, known for its high mitochondrial density, undergoes natural changes as we age, often starting around age 40. Research, including animal studies, has explored the potential effects of long wavelength light (650–900 nm) on mitochondrial function.

Some studies suggest potential benefits of daily exposure to 670 nm light for the function of rods and cones in the eye, though the extent of exposure needed and the duration of its effects are still areas of ongoing research.

With all these variables in mind, the following study published in Nature was conducted.

 Study

The study was conducted in accordance with the Declaration of Helsinki and approved by the UCL research ethics committee (16547/001). Each participant provided written informed consent prior to testing.

Subjects were healthy, of both sexes with an age range of 34–70 years. Each had normal colour vision and were given a general questionnaire regarding eye health prior to testing.

All exposures to 670 nm were for 3 min to the subjects’ dominant eye either in the morning between 8 and 9 AM or the afternoon between 12 and 1 PM and were assessed at either 3h post exposure or 1 week later without further 670 nm exposure in the intervening period.

However, an additional control was undertaken where colour contrast thresholds were measured in the morning and then re-measured 3 h later without exposure to 670 nm. To determine if there were significant shifts in colour contrast sensitivities across the day that were independent of 670 nm and might undermine outcome measures for their exposure, six subjects were repeatedly tested at 0, + 3, + 6 and + 9 h.

Subjects were seated at a fixed distance from the stimulus monitor so that that opto-type letter subtended a 1.3-degree angle on the retina.

All results were taken in triplicate and analysed from initial baseline recordings and final recordings taken after 670 nm exposure at the indicated time points.

The data that support the findings of this study are available on request from the corresponding author GJ. The data are not publicly available due to them containing information that could compromise research participant privacy.

Results 

Preliminary findings from a study indicate that a single 3-minute session with 670 nm light in the morning might be associated with improved color contrast perception in some participants.

If we divide the population that took part in the study by progressive age, in those between 38-49 years it improved 14%, in those 50-59 it improved 20%, in those 60-79 it improved 19%.

They tested the same treatment in the afternoon and the results showed no impact across either colour axis following afternoon light exposure. Hence only the morning light dose is effective.

Time of exposure is critical, as 670 nm light is only effective in the morning. This time dependent effect is likely due to the demonstrated shift in mitochondrial function across the day, and light exposure is likely only effective when synchronised to an aspect of this process.

While early research is promising, indicating potential improvements in cone photoreceptor function from morning exposure to 670 nm light, these findings are preliminary and require further investigation to fully understand their implications.

The subject population was ≥ 35 years because they have previously shown that the impact of 670 nm light on retinal function is reduced in younger subjects, presumably due to the relatively healthy state of their retinal mitochondria. This is consistent with the mitochondrial theory of ageing.

Conclusion 

Initial results from recent research suggest that brief exposure to 670 nm light may have an impact on color contrast sensitivity in certain age groups, potentially bringing it to levels more commonly observed in younger individuals.

These early findings open up interesting avenues for further study, especially regarding the timing of light exposure and its possible benefits.

While this research offers intriguing possibilities, particularly for older individuals, it's important to consult with eye care professionals for personalized advice and treatment.

Study mentioned:

Shinhmar, H., Hogg, C., Neveu, M. et al. Weeklong improved colour contrasts sensitivity after single 670 nm exposures associated with enhanced mitochondrial function. Sci Rep 11, 22872 (2021). https://doi.org/10.1038/s41598-021-02311-1