Deep Red Light Can Improve Fading Sight

Looking at a deep red light for three minutes a day can significantly improve declining eyesight as people age, according to a new study conducted by UCL.

The study, published in the Journals of Gerontology, could signal the dawn of new affordable home-based eye therapies, which would benefit the millions of individuals worldwide who suffer from naturally deteriorating vision.

There are currently over 12 million people over 65 in the United Kingdom. This number is expected to increase by around 20 million in 50 years, and all will have some degree of vision loss due to retinal aging.

“As you age your visual system declines significantly, particularly once over 40. Your retinal sensitivity and your colour 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,” lead author, Professor Glen Jeffery (UCL Institute of Ophthalmology) said.

Cells in the retina of the eye begin to age at the age of 40, and the rate of this aging gains speed in part by the loss of the cell's mitochondria, which produce energy (ATP) and boost cell activity.

Mitochondrial density is highest in photoreceptor cells of the retina, which have high energy demands. As a result, the retina ages more quickly than other organs, with a 70 percent drop in ATP over the course of a lifetime, resulting in a considerable decline in photoreceptor function as they lack the energy to perform their normal function.

Researchers built on previous findings in mice, bumblebees, and fruit flies, which indicated that when their eyes were exposed to 670 nanometre (long wavelength) deep red light, the function of the retina's photoreceptors improved significantly.

“Mitochondria have specific light absorbance characteristics influencing their performance: longer wavelengths spanning 650 to 1000nm are absorbed and improve mitochondrial performance to increase energy production,” said Professor Jeffery.

The retina’s photoreceptor population is formed of cones, which mediate colour vision, and rods, which provide peripheral vision and adapt vision in low/dim light.

The Study

For the study, a total of 24 participants (12 men and 12 women) between the ages of 28 and 72 who had no ocular disease were recruited.

At the beginning of the study, all of the participants' rods and cones were assessed for sensitivity. Rod sensitivity was measured in dark-adapted eyes (with pupils dilated) by having participants identify dim light signals in the dark, and cone function was tested by participants identifying coloured letters with very low contrast that became increasingly blurred, a process known as color contrast.

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. They were then re-tested for their rod and cone sensitivity.

Results

Researchers discovered that the 670nm light had no effect on younger people while it had a considerable effect on those aged 40 and up.

Cone colour contrast sensitivity (the ability to detect colours) improved by up to 20% in some people aged around 40 and over. Improvements were more significant in the blue part of the colour spectrum that is more vulnerable to aging.

Rod sensitivity (the ability to see in low light) also improved significantly in those aged around 40 and over, though less than colour contrast.

Professor Jeffery said: “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.”

“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 £12 to make, so the technology is highly accessible to members of the public.”

This research was funded by the Biotechnology and Biological Sciences Research Council.

*These torches were produced for the study. There are currently no commercially available torches of the same specification.

**Participants placed their eyes over the end of the torch. Eyes could be closed as the red light is not filtered by the eyelid.