Researchers report that a short wave of red light in the morning improves deteriorating eyesight, which may provide a simple, safe, and easy-to-use treatment to keep our eyes sharper as we age.
In tests with 20 participants exposed to three minutes of 670nm deep red light in the morning between 8 a.m. and 9 a.m., eyesight improved 17 percent and lasted (at a lower level) on average a week. In some volunteers, the improvement was up to 20 percent.
This association between longer-wavelength red light and improved vision matches what scientists have seen in previous animal studies, and the study follows a similar study conducted last year — but in this case, the red light was limited to once. Daily exposure that requires less red light energy than previously.
“Using a simple LED device once a week recharges the degraded energy system in retinal cells, like recharging a battery,” says neuroscientist Glenn Jeffrey of University College London (UCL) in the UK.
“And exposure in the morning is absolutely key to achieving improvements in vision deterioration: As we have seen previously in flies, mitochondria have altered working patterns and do not respond in the same way to light in the afternoon – this study confirms it.”
The eye’s mitochondria, often called the centers of cell power, are key: The team already realized that they’re more receptive in the morning, and it’s these organelles that recharge red light so they can produce more energy.
Photoreceptors in the retina, where mitochondria are more densely collected, consist of cones (deal with color vision) and rods (adapt to low light). Here, the team focused on cones, assessing color contrast sensitivity after exposure to red light.
Follow-up tests on six participants, using red light therapy daily between 12 p.m. and 1 p.m., resulted in no change in vision — confirming that mitochondria do not respond to deep red light in the same way later in the day.
above: Dr. Pardis Kaynezhad holds a deep red light over her eye, which helps stimulate mitochondria in the cells of the retina.
“Mitochondria are particularly sensitive to light of a long wavelength, which affects their performance,” Jeffrey says. “Longer wavelengths extending from 650 to 900 nanometers improve the performance of mitochondria for increased energy production.”
Cells in the human retina begin to age once we reach the age of 40 or so, and this aging is partly caused by a slowing of the mitochondrial energy supply. Since the photoreceptors in the retina require more energy, they tend to age faster as well.
The simple, low-power LED device used in the study may be an affordable vision therapy that people can quickly apply. It’s probably safe to use as well, as the 670nm infrared light isn’t much different from the light found in the natural environment.
It will take some time to develop a completed device for widespread use, however, the researchers caution that some of their data is “loud”: the level of improvement varied among participants, even those of the same age. Future studies could look more closely at other variables that may influence the results.
“This simple, population-wide intervention will significantly impact quality of life as people age, and is likely to lower the social costs that arise from problems associated with low vision,” Jeffrey says.
The search was published in Scientific Reports.