Just three minutes of exposure to deep red light once a week, when delivered in the morning, can significantly improve declining eyesight, finds a pioneering new study by UCL researchers.

Published in Scientific Reports, the study builds on the team’s previous work,[1] which showed daily three-minute exposure to longwave deep red light ‘switched on’ energy producing mitochondria cells in the human retina, helping boost naturally declining vision.  .

Furthermore, building on separate UCL research in flies[2] that found mitochondria display ‘shifting workloads’ depending on the time of day, the team compared morning exposure to afternoon exposure.

In summary, researchers found there was, on average, a 17% improvement in participants’ color contrast vision when exposed to three minutes of 670 nanometers (long wavelength) deep red light in the morning and the effects of this single exposure lasted for at least a week.

Scientists say the benefits of deep red light, highlighted by the findings, mark a breakthrough for eye health and should lead to affordable home-based eye therapies, helping the millions of people globally with naturally declining vision.

Lead author, Professor Glen Jeffery (UCL Institute of Ophthalmology), said: “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.

In studying the effects of deep red light in humans, researchers built on their previous findings in mice, bumblebees and fruit flies, which all found significant improvements in the function of the retina’s photoreceptors when their eyes were exposed to 670 nanometres (long wavelength) deep red light.

“Mitochondria have specific sensitivities to long wavelength light influencing their performance: longer wavelengths spanning 650 to 900nm improve mitochondrial performance to increase energy production,” said Professor Jeffery.

The retina’s photoreceptor population is formed of cones, which mediate color vision, and rods, which adapt vision in low/dim light.

All the participants were aged between 34 and 70, had no ocular disease, completed a questionnaire regarding eye health prior to testing, and had normal color vision (cone function).

Using a provided LED device all 20 participants (13 female and 7 male) were exposed to three minutes of 670nm deep red light in the morning between 8am and 9am.

Their color vision was then tested again three hours post exposure and 10 of the participants were also tested one week post exposure. .

On average there was a ‘significant’ 17% improvement in colour vision, which lasted a week in tested participants; in some older participants there was a 20% improvement, also lasting a week.

A few months on from the first test (ensuring any positive effects of the deep red light had been ‘washed out’) six (three female, three male) of the 20 participants, carried out the same test in the afternoon, between 12pm to 1pm.  When participants then had their color vision tested again, it showed zero improvement.

“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.”.

This has the effect of dimming the light but does not affect the wavelength.

“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.”?