A new UCL study shows that three minutes of deep red light once a week in the morning can considerably repair declining eyesight.
The discovery, which was published in Scientific Reports, builds on the team’s prior work, which found that daily three-minute exposure to longwave deep red light ‘switched on’ energy-producing mitochondria cells in the human retina, boosting normally deteriorating eyesight.
The purpose of this current study was to determine the effect of a single three-minute exposure while also employing far lower energy levels than in earlier investigations. Additionally, based on previous UCL research in flies that discovered mitochondria exhibit ‘shifting workloads’ according to the time of day, the team examined morning and afternoon exposure.
In summary, researchers discovered that when individuals were exposed to three minutes of 670 nanometre (long wavelength) deep red light in the morning, their color contrast vision improved by an average of 17%, and the effects lasted for at least a week. When the same test was repeated in the afternoon, however, no improvement was observed.
According to scientists, the findings demonstrate the benefits of deep red light for eye health and should pave the way for affordable home-based eye therapies to treat the millions of individuals worldwide who suffer from naturally decreasing vision.
Professor Glen Jeffery (UCL Institute of Ophthalmology), the study’s lead author, says: “We demonstrate that one single exposure to long wave deep red light in the morning can significantly improve declining vision, which is a major health and wellbeing issue, affecting millions of people globally.
“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.”
Around the age of 40, cells in the retina of the eye begin to age, and the rate of this aging is accelerated by the loss of the cell’s mitochondria, which are responsible for producing energy (known as ATP) and enhancing cell function.
The highest mitochondrial density is seen in the photoreceptor cells of the retina, which have a high energy demand. As a result, the retina ages more rapidly than other organs, losing 70% of its ATP over time, resulting in a considerable drop in photoreceptor performance due to a lack of energy to execute its usual function.
When investigating the effects of deep red light in humans, researchers built on their previous findings in mice, bumblebees, and fruit flies, which all discovered significant improvements in the function of the retina’s photoreceptors when their eyes were exposed to deep red light with a wavelength of 670 nanometres (a long wavelength) or longer.
“Mitochondria have specific sensitivities to long wavelength light influencing their performance: longer wavelengths spanning 650 to 900nm improve mitochondrial performance to increase energy production,” says Professor Jeffery.
The photoreceptor population of the retina is composed of cones, which are responsible for color vision, and rods, which are responsible for visual adaptation in low/dim light. This study concentrated on cones and measured color contrast sensitivity along the protan axis (which measured red-green contrast) and the tritan axis (blue-yellow).
All of the subjects were between the ages of 34 and 70, had no ocular disease, had completed an eye health questionnaire prior to testing, and had normal color vision (cone function). This was determined via a ‘Chroma Test,’ which involved distinguishing colored letters with very low contrast and gradually fuzzy appearances, a process known as color contrast.
All 20 participants (13 females and 7 males) were exposed to three minutes of 670nm deep red light between 8 and 9 a.m. using a given LED device. Three hours after the exposure, their color vision was checked again, and ten of the subjects were also evaluated one week later.
In tested subjects, there was an average of a ‘significant’ 17 percent increase in color vision that lasted a week; in some older people, there was a 20 percent improvement that lasted a week.
Six (three female, three male) of the 20 participants repeated the test in the afternoon, between 12pm and 1pm, a few months following the initial (to ensure any favorable effects of the deep red light had been ‘washed out’). When participants’ color vision was tested again, there was no improvement.
Professor Jeffery says: “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.
“And 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.”
The light energy emitted by the LED torch for this investigation was just 8mW/cm2, rather than the 40mW/cm2 that they had previously utilized. This causes the light to fade, but it has no effect on the wavelength. While all energy levels are entirely safe for the human eye, further lowering the energy is a bonus.
“The technology is simple and very safe; the energy delivered by 670nm long wave light is not that much greater than that found in natural environmental light.”
“Given its simplicity, I am confident an easy-to-use device can be made available at an affordable cost to the general public.
“In the near future, a once a week three-minute exposure to deep red light could be done while making a coffee, or on the commute listening to a podcast, and such a simple addition could transform eye care and vision around the world.”
Despite the clarity of the results, some of the data is “noisy,” according to the experts. While the benefits of 670nm exposure are evident, the amount of the advantages can differ significantly between people of similar ages. As a result, caution is required while interpreting the results. It’s likely that there are other factors influencing the degree of improvement that the researchers haven’t discovered yet, which would necessitate a larger sample size.
Source: 10.1038/s41598-021-02311-1
Image Credit: iStock
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