If the results are replicated in future studies and approved by the US Food and Drug Administration, the light could augur a new era in which millions of people have access to simple therapy at home. It would give them a new layer of protection against natural aging processes that rob our eyes of sensitivity to light and the ability to distinguish colors.
"You don't need to use it for a long time to start getting a solid result," said lead author Glen Jeffery, professor of neuroscience at college College Institute of Ophthalmology London.
Science works, Jeffery said, because light stimulates the health of mitochondria, which are like batteries in our cells.
And because mitochondria are involved in a wide range of diseases, ideas like these could help lead to new treatments for diseases like Parkinson's and diabetes.
All you need is a few minutes
The study was small, a pilot study to test the concept. The researchers recruited 12 men and 12 women, ranging in age from 28 to 72. Each participant received a small flashlight that emitted a red light with a wavelength of 670 nanometers. That wavelength is towards the long end of the visible spectrum, and just below an infrared wavelength, which tends to be invisible to the human eye.
They spent three minutes each day looking at the light over a two-week period.
The researchers measured the function of the cone in the subjects' eyes by having them identify colored letters with low contrast. And they measured the sensitivity of the rod in their eyes asking them to detect light signals in the dark.
There was a 14% improvement in the ability to see colors, or the contrast sensitivity of the cone color, for the two dozen participants.
However, the improvement was more significant in study participants older than 40 years. For those ages, cone color contrast sensitivity increased by 20%. in the course of the study.
That age group also experienced significant increases in the bar threshold, which corresponds to the ability to see in low light. Study participants under the age of 40 also experienced some improvement, but did not see the same jump as the older subjects. Younger eyes have not decreased as much as older eyes.
"The retina ages faster than any other organ in your body" Jeffery said. "From an evolutionary perspective, we've fundamentally never lived more than 40 years."
Now, of course, we regularly live well beyond that age, and we need ways to nurture the organs that for millennia have been most prone to wear and tear in life.
These diseases can occur in young people, but their prevalence increases with age. In the initial stages, these conditions are treatable, although they may begin to appear before symptoms appear.
It is easy and safe to use.
This new human study is based on results in fruit flies and mice, which also showed that red light could improve the functioning of mitochondria.
Independent long-term safety studies of red lights in humans would have to yield similar benefits for this method of eye protection to be approved by the FDA. If so, you would still need to use a properly tested product under the supervision of a doctor.
One of the best assets of the red lights they used is that they are safe, Jeffery said. All of the researchers tested the red lights in their own eyes before starting the study and found no ill effects. The research subjects in the study also reported no adverse effects.
"If you use this every day, we have no evidence to say it is harmful," said Jeffery.
That fits with previous research, where red light safety has long been established, explained Dr. Raj Maturi, an associate professor at the Indiana University School of Medicine.
"It would be a very easy path for FDA approval," he said.
But more studies are needed to show it helps
Although these lights are not harmful, Maturi was also not prepared to accept the idea that they are incredibly useful.
He noted that this pilot study lacked a control group of patients who may have been exposed to a dummy light it emitted. The results found in this small study of 24 participants may not be valid in the larger population. Of the subjects over the age of 40 in this study, the individual characteristics of some of them would be enough to make the vision improvements look stronger than they really are.
"The data set could be reduced by three or four subjects," he said.
And although participants improved the way they viewed the blue color axis, Maturi noted that they had no statistically significant gains in the way they viewed the red color axis.
To really test these ideas, a double-blind controlled study with a larger group of subjects and longer monitoring over time will be needed.
LED lights could help with many illnesses.
Therefore, stimulating the mitochondria to reduce damage is one way to delay aging in general. Our retinas are packed with mitochondria, the highest concentration of mitochondria of any part of the body.
That's one main reason why Jeffery and his colleagues tried to test red lights in a specific area of aging, such as decreased vision. Mitochondria absorb longer wavelengths of light, making near-infrared light their preferred choice for testing.
Red lights can improve function in a variety of diseases, particularly in the mitochondria in those who are aging with conditions like Parkinson's, he noted.
"Each disease could have a mitochondrial angle," said Jeffery. "In diabetes, for example, your mitochondria are very upset."
Each application carries the same human desire to defend against processes that are both natural and universal.
"We will all suffer from aging. So let's try to go smoothly if we can," he said.