Just 3 minutes of exposure to deep red light in the morning for at least a week can significantly improve declining eyesight, according to a study from University College London (UCL) that could mark a breakthrough for eye health.
All of the estimated 12 million people in the UK aged over 65 will experience some degree of visual decline because of retinal ageing. This is due in part to a reduction in mitochondrial production of adenosine triphosphate (ATP), which provides the energy for cellular functions. The retina ages faster than other organs because of high mitochondrial density in photoreceptors, particularly the cones that mediate colour vision and which have high energy demands. With age, ATP production can reduce by up to 70%, leading to significant declines in photoreceptor function and gradually undermining both retinal sensitivity and colour vision.
The UCL team had previously shown that even brief exposure to wavelengths of deep red light can ‘switch on’ retinal mitochondria again and improve ATP production, resulting in significant improvements in declining eyesight in people over 40.
The latest study, published in Nature Scientific Reports , looked at the effect of a single 3-minute exposure to 670nm deep red light using lower energy levels, 8mW/cm2, rather than the 40mW/cm2 used previously, delivered by an LED torch-like device held over the dominant eye. Participants - 13 women and 7 men aged 34-70 years, who had no known ocular disease and normal colour vision - used the light for just 3 minutes between 8 AM and 9 AM. Their colour vision was tested 3 hours later, and 10 of them were also tested one week post-exposure.
Recharging the Retina
Results showed an average 17% improvement in colour vision after red light exposure, and this was maintained for a week. The level of improvement reached 20% in some older participants.
Control tests were undertaken by measuring colour contrast thresholds in the morning and then again 3 hours later without red light exposure and showed no difference between the two measurements. A subset of participants was tested repeatedly, at 8 AM, 11 AM, 2 PM, and 5 PM, to check for possible shifts in colour contrast sensitivities across the day independent of red light exposure and revealed no significant variation. These tests confirmed that the improvements seen in the main group were due to the 670nm light exposure.
Professor Glen Jeffery of the Institute of Ophthalmology at UCL, who led the research, said in a press release: "Using a simple LED device once a week recharges the energy system that has declined in the retina cells, rather like re-charging a battery."
In addition, following laboratory research on flies suggesting that retinal cells respond differently at different times of day, the team compared morning and afternoon exposures. After an interval of several months, to ensure no continuing effect of the first test, six of the participants were given the same 3-minutes exposure but now between 12 PM and 1 PM. This time the light had no effect on their colour vision.
Morning Exposure is Key
"Time of exposure is critical," they concluded. It seems 670nm 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." As there are times when mitochondria seem to be particularly sensitive, they are now mapping sensitivities to try to find the optimum time for red light exposure.
"Morning exposure is absolutely key to achieving improvements in declining vision: as we have previously seen in flies, mitochondria have shifting work patterns and do not respond in the same way to light in the afternoon – this study confirms this," said Prof Jeffery.
The study concluded: "Single exposures to 670nm light delivered in the morning, at only 8mW/cm2 have the ability to improve cone photoreceptor function in aged subjects to levels commonly found in much younger individuals and can be sustained for up to a week."
Declining vision with age is "a major health and wellbeing issue, affecting millions of people globally", Prof Jeffery said. “This simple intervention applied at the population level would significantly impact on quality of life as people age and would likely result in reduced social costs that arise from problems associated with reduced vision.
The team anticipated that their research could lead to accessible and affordable home-based eye therapies. To that end, Prof Jeffery has been working for no commercial gain with Planet Lighting UK in Wales in the development of a device for general use.
He told Medscape UK: "The deal I struck with the company was that I gave them the key data needed to produce the glasses on the understanding they would produce them for minimal profit and put some of this back into some form of research."
Rather than the hand-held monocular device used in the study, the commercial version will be like a pair of glasses with LEDs in front of each eye. "They look very professional. I have tested the prototypes," Prof Jeffery told us.
There may be other applications of red light therapy in future. "We are working on... what else it can be applied to. It works on mitochondria, which control metabolism and ageing. We are slowing an aspect of ageing including the rate at which cells die in the retina. You have a 30% loss over life, but long wavelengths significantly reduce this. We are also looking at environmental lighting – the big question."
Meanwhile, although production has been delayed due to pandemic measures and a shortage of electronic components from the Far East, the device, called "eyepower red", should be available early next year.
According to Prof Jeffery: "In the near future, a once a week 3-minute exposure to deep red light could be done while making a coffee, or on the commute listening to a podcast. Such a simple addition could transform eye care and vision around the world."
The research was funded by the Biotechnology and Biological Sciences Research Council, and Sight Research UK.
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Cite this: Dr Sheena Meredith MB BS. Red Light in the Morning Boosts Failing Eyesight - Medscape - Nov 29, 2021.