Looking at 670-nm red light for three minutes a day can significantly improve cone color contrast sensitivity (the ability to detect colors) and rod sensitivity (the ability to see in low light), according to a new study published in the Journals of Gerontology: Series A.
“As you age your visual system declines significantly, particularly once over 40. Your retinal sensitivity and color vision are both gradually undermined, and with an aging population, this is an increasingly important issue,” said Professor Glen Jeffery, a researcher in the Institute of Ophthalmology at University College London.
“To try to stem or reverse this decline, we sought to reboot the retina’s aging cells with short bursts of longwave light.”
In humans around 40 years old, cells in the eye’s retina begin to age, and the pace of this aging is caused, in part, when the cell’s mitochondria, whose role is to produce energy — carried by adenosine triphosphate (ATP) molecules — and to boost cell function, also start to decline.
Mitochondrial density is greatest in the retina’s photoreceptor cells, which have high energy demands.
As a result, the retina ages faster than other organs, with a 70% ATP reduction over life, causing a significant decline in photoreceptor function as they lack the energy to perform their normal role.
The scientists 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 their eyes were exposed to 670-nm 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,” Professor Jeffery said.
“The retina’s photoreceptor population is formed of cones, which mediate color vision and rods, which provide peripheral vision and adapt vision in low/dim light.”
The study involved 24 people (12 male, 12 female), aged between 28 and 72, who had no ocular 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, and cone function was tested by subjects identifying coloured letters that had very low contrast and appeared increasingly blurred, a process called colour contrast.
The participants were then given a small LED torch to take home and were asked to look into its deep red 670-nm light beam for three minutes a day for two weeks.
They were then re-tested for their rod and cone sensitivity.
The researchers found the 670-nm light had no impact in younger individuals, but in those around 40 years and over, significant improvements were obtained.
Cone color contrast sensitivity improved by up to 20% in some people aged around 40 and over.
Improvements were more significant in the blue part of the color spectrum that is more vulnerable in aging.
Rod sensitivity also improved significantly in those aged around 40 and over, 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,” Professor 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 USD to make, so the technology is highly accessible to members of the public.”
Harpreet Shinhmar et al. Optically improved mitochondrial function redeems aged human visual decline. Journals of Gerontology: Series A, published online June 29, 2020; doi: 10.1093/gerona/glaa155
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