morning exposure to deep red light improves declining eyesight

Dr Pardis Kaynezhad (UCL Institute of Ophthalmology) holds a deep red light over her eye – Dr Pardis Kaynezhad (UCL Institute of Ophthalmology) holds a deep red light over her eye, which helps stimulate the mitochondria in her retinal cells.

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*, 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.  

For this latest study, scientists wanted to establish what effect a single three-minute exposure would have, while also using much lower energy levels than their previous studies. Furthermore, building on separate UCL research in flies** 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’ colour contrast vision when exposed to three minutes of 670 nanometre (long wavelength) deep red light in the morning and the effects of this single exposure lasted for at least a week. However, when the same test was conducted in the afternoon, no improvement was seen.

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.

“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.”

Naturally declining vision and mitochondria

In humans around 40 years old, cells in the eye’s retina begin to age, and the pace of this ageing is caused, in part, when the cell’s mitochondria, whose role is to produce energy (known as ATP) and boost cell function, also start to decline.

Mitochondrial density is greatest in the retina’s photoreceptor cells, which have high energy demands. As a result, the retina ages faster than other organs, with a 70% ATP reduction over life, causing a significant decline in photoreceptor function as they lack the energy to perform their normal role.

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 nanometre (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.

Morning and afternoon studies

The retina’s photoreceptor population is formed of cones, which mediate colour vision, and rods, which adapt vision in low/dim light. This study focused on cones*** and observed colour contrast sensitivity, along the protan axis (measuring red-green contrast) and the tritan axis (blue-yellow).

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 colour vision (cone function). This was assessed using a ’Chroma Test’: identifying coloured letters that had very low contrast and appeared increasingly blurred, a process called colour contrast.   

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 colour 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 colour vision tested again, it showed zero improvement.

Professor Jeffery said: “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.”

For this study the light energy emitted by the LED torch was just 8mW/cm2, rather than 40mW/cm2, which they had previously used. This has the effect of dimming the light but does not affect the wavelength. While both energy levels are perfectly safe for the human eye, reducing the energy further is an additional benefit.

Home-based affordable eye therapies

With a paucity of affordable deep red-light eye-therapies available, Professor Jeffery has been working for no commercial gain with Planet Lighting UK, a small company in Wales and others, with the aim of producing 670nm infra-red eyewear at an affordable cost, in contrast to some other LED devices designed to improve vision available in the US for over $20,000.

“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,” Professor Jeffery said.

“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.”

Study limitations

Despite the clarity of the results, researchers say some of the data are “noisy”. While positive effects are clear for individuals following 670nm exposure, the magnitude of improvements can vary markedly between those of similar ages. Therefore, some caution is needed in interpretating the data. It is possible that there are other variables between individuals that influence the degree of improvement that the researchers have not identified so far and would require a larger sample size.

To help meet the costs of this research and future research, Professor Glen Jeffery’s Lab at the UCL Institute of Ophthalmology receives donations via UCL’s Give Now platform. To support this work, go to:  Give Now

* Declining eyesight improved by looking at deep red light  &  Journals of Gerontology

**  ’A day in the life of mitochondria reveals shifting workloads’ in Scientific Reports

***Only cones not rods were tested in this study; similar previous research identified a comparable effect on cones and rods, satisfying the team any effect on cones could be translated to rods.

Henry Killworth 

Tel: +44 (0) 7881 7883274

E: h.killworth [at]



Tracking contaminated water from the Fukushima nuclear accident

(a) Sub-processes of macroscopic and microscopic diffusion analyses and their relationships. Results of (b) macroscopic and (c) microscopic diffusion analyses for 1 unit relative concentration of approximately 29Bq/m3. (d) Variations in the pollutant concentration in the waters near the three coastal cities. (e) Comparison of the pollutant concentration curves ...

View more: Tracking contaminated water from the Fukushima nuclear accident

Climate mapping algorithm shows temperatures rising, especially daily lows

Credit: Oregon State University Oregon State University’s new maps of 30-year U.S. climate “normals” show the area east of the Rockies is getting wetter, the Southwest is getting drier, and temperatures are inching upward—with daily lows rising faster than daily highs. “When we publish the new normals every 10 ...

View more: Climate mapping algorithm shows temperatures rising, especially daily lows

Climate change is making monogamous albatrosses divorce

Changing environmental conditions can put stress on coupled-up animals. Credit: Natasha Gillies, Author provided Not all relationships end in “happily ever after,” and birds are no exception. While more than 90% of bird species form monogamous couples, many of these will end in divorce. The reasons for splitting up ...

View more: Climate change is making monogamous albatrosses divorce

First report published on UCL and the UN Sustainable Development Goals

An image of the front cover of the UCL SDGs report UCL has published its first report setting out how the university is addressing the UN Sustainable Development Goals (SDGs). Developed by the UCL Sustainable Development Goals Initiative (SDGI), the report showcases a selection of the hundreds of ways ...

View more: First report published on UCL and the UN Sustainable Development Goals

Less snow, more rain in store for the Arctic, study finds

Rain falls in Sarek National Park, in Sweden. Credit: Shutterstock The Arctic is often thought of as a cold, white and snowy region, but this image is rapidly changing. The Arctic is currently warming much faster than the rest of the planet and is experiencing rapid sea ice loss. ...

View more: Less snow, more rain in store for the Arctic, study finds

Delhi shuts schools again after court warning to curb pollution

Credit: Pixabay/CC0 Public Domain India’s polluted capital again ordered schools closed on Thursday over dangerous smog levels, as the country’s top court demanded officials take action to address the toxic haze. New Delhi, one of the world’s most polluted cities and home to about 20 million people, is cloaked ...

View more: Delhi shuts schools again after court warning to curb pollution

Do La Nina's rains mean boom or bust for Australian farmers?

Credit: Shutterstock After years of punishing drought in some areas, many farmers in Australia’s east were hoping the newly declared La Niña event would bring them good rains. Many are now rejoicing, with the wettest November experienced in Australia for more than two decades. But for some farmers, heavy ...

View more: Do La Nina's rains mean boom or bust for Australian farmers?

1st Space Council meeting under VP Harris highlights climate change, competitiveness and responsible space behavior

We just got a look at some of the Biden administration's top space priorities.

View more: 1st Space Council meeting under VP Harris highlights climate change, competitiveness and responsible space behavior

Ocean plastic is creating new communities of life on the high seas

Efforts to restore Indonesian peatlands could save billions in wildfire costs

Climate modeling confirms historical records showing rise in hurricane activity

Personen mit niedrigem Einkommen stärker von Pandemie belastet

City butterflies keep flying for longer

Study: Climate change not causing Madagascar drought, famine

Island turns into open-air lab for tech-savvy volcanologists

Toyota and Volkswagen among car manufacturers refusing to sign COP26 emissions proposal

Madagascar food crisis caused more by poverty, natural weather than climate change - study

Researchers investigate combined effect of drought, fire on stream communities, highlighting importance of headwaters

Heat, no food, deadly weather: Climate change kills seabirds

Science report: US should make less plastic to save oceans