A Certain Frequency of Red Light Boosted People’s Eyesight in New Study

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Scientists in the UK think they may have found a cheap, low-tech way to help fight age-related loss of vision. In a small clinical trial, people over 40 who were told to stare into a deep red light for three minutes a day had noticeable improvements to their sight. They reported being able to see better in the dark and to better distinguish colors.


Red light is already commonly used as a skin treatment. The idea is that longer wavelengths of light have a unique regenerative effect on mitochondria, the parts of a cell that process the body’s fuel to keep it running. These wavelengths range from just behind the point where we stop seeing visible light (deep red in color) to infrared light. Mitochondria absorb this energy, which is theorized to improve their performance. That, in turn, is supposed to improve the body’s ability to heal wounds, reduce inflammation and pain, and even regrow hair, depending on where the light is applied.

Mitochondria are in almost every type of cell. But they’re especially abundant in the retina, the thin layer of the eye that captures light from the outside world and translates it into information that’s sent to the brain. Without the retina, we simply couldn’t see. But as we age, the retina’s mitochondria start to break down at a faster pace than mitochondria elsewhere. This dysfunction is thought to play a crucial role in the age-related decline of our vision, as well as other degenerative eye disorders.

“However, mitochondria absorb some forms of light, including deep red, and this recharges the battery improving cell function—this works well in the retina because they have so many mitochondria. Hence we use this to improve vision,” lead author Glen Jeffery, an eye researcher at University College London, told Gizmodo via email. 

Jeffery and his team had earlier experimented with mice, bees, and flies, finding that red light could improve the performance of the retina in all three. But their new study, published in The Journals of Gerontology, involved people.  

In this trial, they recruited 24 people between the ages of 28 and 72, all with no known eye problems. For two weeks, the volunteers were told to stare at a red light “torch” for three minutes every day, a device that cost the researchers roughly $15 to make (the light wavelengths were 670 nanometers). Before and after the experiment, they were given tests that measured how well they could see in the dark, as a test of the retina’s rods, and how well they could see contrast between colors, as a test of the retina’s cones.

An example of handheld LED torch used in study.
An example of handheld LED torch used in study.
Photo: University College London (Other)

In those under 40, the average performance on the tests stayed the same before and after the therapy. But for people over 40, they did better on both tests post-therapy. Improvement was statistically significant for both tests, though people generally did better on the color contrast test.

The findings are only a proof of concept for now, especially because they only involved healthy people. “But as vision declines so much with age, it becomes a big issue for society and the individual,” Jeffery said.  


The results are certainly intriguing, but it will take more studies involving many, many more people to know whether such a therapy is truly effective. While red light therapy is unlikely to be dangerous (it’s also called low-light therapy, since the heat generated by it doesn’t harm cells), its actual track record for any number of potential health applications is still largely anecdotal and unproven.

This doesn’t mean that these results are invalid or that we won’t someday recommend a regular dose of red light to older people worried about their eyesight. It just means we should be careful and wait for further evidence to come in before we all start gazing into red flashlights.


Jeffery and his team are already conducting their next experiments. So far their work suggests that people may be able to get the same helpful effects from staring into a red light every other day or even every three days as they do from a daily dose. They’re also now using shorter, weaker doses of red light in their trials, and they hope to figure out why some people’s vision seems to respond better to the therapy than others.

This article was updated with comments from the lead author.



Lost credentials again

Perhaps the exact frequency of red light should be mentioned in the article?

All participants were then given a small LED torch to take home and were asked to look into its deep red 670nm light beam for three minutes a day for two weeks.