• Share

PRINT

Staring at a deep red light for three minutes a day can significantly improve declining eyesight, according to a new study from University College London, the first of its kind in humans.

Scientists believe the discovery, published in The Journals of Gerontology, Series A: Biological Sciences and Medical Sciences, could signal the dawn of new, affordable home-based eye therapies, helping the millions of people globally with naturally declining vision.

“As you age your visual system declines significantly, particularly once over 40,” said lead author, professor Glen Jeffery of the UCL Institute of Ophthalmology.

“Your retinal sensitivity and your color vision are both gradually undermined, and with an aging population, this is an increasingly important issue. To try to stem or reverse this decline, we sought to reboot the retina’s aging cells with short bursts of longwave light.”

How red light helps

In humans around 40 years old, cells in the eye’s retina begin to age faster than in other organs. This is caused, in part, by the decline in ability of the cells’ mitochondria to fuel cell functions by producing ATP (adenosine triphosphate).

The retina’s photoreceptor cells include cones, which are responsible for color vision, and rods, which provide peripheral vision and adapt vision in low or dim light.

These cells have high-energy demands, so they possess greater numbers of mitochondria. However, over a lifespan, ATP is reduced in retinal cells by 70%, causing a significant decline in photoreceptor function as cells lack the energy needed to perform their normal roles.

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 exposed to 670 nanometer (long wavelength) deep red light.

“Mitochondria have specific light-absorbance characteristics influencing their performance: Longer wavelengths spanning 650 to 1,000 nm are absorbed and improve mitochondrial performance to increase energy production,” Jeffery said.

How the study worked

Researchers recruited 24 people (12 male and 12 female) without eye disease. All participants’ eyes were tested for the sensitivity of their rods and cones at the start of the study.

Rod sensitivity was measured in dark-adapted eyes (with pupils dilated) by asking participants to detect dim light signals in the dark. Cone function was tested by subjects identifying colored letters that had very low contrast and appeared increasingly blurred, a process called color contrast.

All participants were then given a small LED flashlight to take home and were asked to look into its deep red 670 nm light beam for three minutes a day for two weeks. (Participants placed their eye over the end of the flashlight. Eyes could be closed, as the red light is not filtered by the eyelid.)

After the two weeks, they were re-tested for their rod and cone sensitivity. Researchers found the 670 nm light had no impact on the vision of younger individuals, but in those around 40 years and over, significant improvements were observed.

The ability to detect colors (known as cone color contrast sensitivity) improved by approximately 20% in people aged around 40 and over. Improvements were higher in the blue part of the color spectrum that is more vulnerable to aging.

Rod sensitivity (the ability to see in low light) also improved significantly in the older subjects, though less than color contrast.

“Our study shows that it is possible to significantly improve vision that has declined in aged individuals using simple brief exposures to light wavelengths that recharge the energy system that has declined in the retina cells, rather like re-charging a battery,” Jeffery said.

“The technology is simple and very safe, using a deep red light of a specific wavelength that is absorbed by mitochondria in the retina that supply energy for cellular function. Our devices cost about $15 to make, so the technology is highly accessible to members of the public.”

Jeffery said further studies are continuing to determine the amount of time the red light should be used daily for optimal improvement.