A few minutes of looking into a deep red light could have a dramatic effect on preventing eyesight decline as we age, according to a new study published this week in The Journals of Gerontology.
"You don't need to use it for very long to start getting a strong result," said lead author Glen Jeffery, a professor of neuroscience at University College London's Institute of Ophthalmology.
The science works, Jeffery said, because the light stimulates the health of mitochondria, which are like batteries in our cells.
mitochondria[ˌmaɪto'kɑndrɪr]: n. 线粒体（mitochondrion的复数）
And because mitochondria are implicated in a broad range of diseases, insights like these could help lead to new treatments for diseases including Parkinson's and diabetes.
The study was small, a pilot study to test the concept. Researchers recruited 12 men and 12 women, whose ages ranged from 28 to 72. Each participant was given a small handheld flashlight that emitted a red light with a wavelength of 670 nanometers. That wavelength is toward the long end of the visible spectrum, and just short of an infrared wavelength, which tends to be invisible to the human eye.
They spent three minutes each day looking into the light over a period of two weeks.
The lights work on both cones and rods in the eye. Cones are photo receptor cells that detect color and work best in well-lit situations. Rods, which are much more plentiful, are retina cells that specialize in helping us see in dim light, according to the American Academy of Ophthalmology.
Researchers measured the cone function in subjects' eyes by having them identify colored letters with low contrast. And they measured their eyes' rod sensitivity by asking them to detect light signals in the dark.
There was a 14% improvement in the ability to see colors, or cone color contrast sensitivity, for the entire two dozen participants.
Improvement, however, was most significant in study participants over age 40. For those ages, cone color contrast sensitivity rose by 20% over the course of the study.
That age bracket also saw significant increases in rod threshold, which corresponds to the ability to see in low light. Study participants under 40 also experienced some improvement, but didn't see the same jump as older subjects. Younger eyes haven't declined as much as older eyes.
"The retina ages faster than any other organ in your body," Jeffery said. "From an evolutionary perspective, we fundamentally have never lived past 40."
Now, of course, we regularly live well beyond that age, and need ways to nurture the organs that for millennia have been the most likely to wear out earliest in life.
But more studies are needed to prove it helps.
"We're all going to suffer from aging. So let's try to go gently if we can," Jeffery said.