Vision Improved By Exercise and Deep Red Light Exposure, Two Studies Find
In the first study, moderate amounts of exercise reduced the harmful overgrowth of blood vessels in the eyes of mice by up to 45%; blood vessel tangles are responsible for macular degeneration.
In the second study, adults over age 40 who placed a small LED torch that gave off a deep red wavelength light over their eyelids for 3 minutes per day for 2 weeks experienced improvements in cone color and rod sensitivity.
This translated to better ability to detect between colors and ability to see in low light.
Exercise can slow or prevent the development of macular degeneration and may benefit other common causes of vision loss, such as glaucoma and diabetic retinopathy, new research suggests.
The new study from the University of Virginia School of Medicine found that exercise reduced the harmful overgrowth of blood vessels in the eyes of lab mice by up to 45%. This tangle of blood vessels is a key contributor to macular degeneration and several other eye diseases.
The study represents the first experimental evidence showing that exercise can reduce the severity of macular degeneration, a leading cause of vision loss, the scientists report. Ten million Americans are estimated to have the condition.
"There has long been a question about whether maintaining a healthy lifestyle can delay or prevent the development of macular degeneration. The way that question has historically been answered has been by taking surveys of people, asking them what they are eating and how much exercise they are performing," said researcher Bradley Gelfand, PhD, of UVA's Center for Advanced Vision Science.
"That is basically the most sophisticated study that has been done. The problem with that is that people are notoriously bad self-reporters ... and that can lead to conclusions that may or not be true. This [study] offers hard evidence from the lab for very first time."
Enticingly, the research found that the bar for receiving the benefits from exercise was relatively low - more exercise didn't mean more benefit. "Mice are kind of like people in that they will do a spectrum of exercise. As long as they had a wheel and ran on it, there was a benefit," Gelfand said. "The benefit that they obtained is saturated at low levels of exercise."
An initial test comparing mice that voluntarily exercised versus those that did not found that exercise reduced the blood vessel overgrowth by 45%. A second test, to confirm the findings, found a reduction of 32%.
The scientists aren't certain exactly how exercise is preventing the blood vessel overgrowth. There could be a variety of factors at play, they say, including increased blood flow to the eyes.
Gelfand, of UVA's Department of Ophthalmology and Department of Biomedical Engineering, noted that the onset of vision loss is often associated with a decrease in exercise. "It is fairly well known that as people's eyes and vision deteriorate, their tendency to engage in physical activity also goes down," he said. "It can be a challenging thing to study in older people. ... How much of that is one causing the other?"
The researchers already have submitted grant proposals in hopes of obtaining funding to pursue their findings further.
"The next step is to look at how and why this happens, and to see if we can develop a pill or method that will give you the benefits of exercise without having to exercise," Gelfand said. "We're talking about a fairly elderly population [of people with macular degeneration], many of whom may not be capable of conducting the type of exercise regimen that may be required to see some kind of benefit." (He urged people to consult their doctors before beginning any aggressive exercise program.)
Gelfand, a self-described couch potato, disclosed a secret motivation for the research: "One reason I wanted to do this study was sort of selfish. I was hoping to find some reason not to exercise," he joked. "It turned out exercise really is good for you."
Scientists believe the discovery, published in the Journals of Gerontology, could signal the dawn of new affordable home-based eye therapies, helping the millions of people globally with naturally declining vision.
In the UK there are currently around 12 million people aged over 65: in 50 years this will increase to around 20 million and all will have some degree of visual decline because of retinal ageing.
Lead author, Professor Glen Jeffery (UCL Institute of Ophthalmology) said: “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 ageing population, this is an increasingly important issue.
“To try to stem or reverse this decline, we sought to reboot the retina’s ageing 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 ageing is caused, in part, when the cell’s mitochondria, whose role is to produce energy (known as ATP) and 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.
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 their eyes were exposed to 670 nanometre (long wavelength) deep red light.
“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.
For the study, 24 people (12 male, 12 female), aged between 28 and 72, who had no ocular disease, were recruited. 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.
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
Researchers found the 670nm light had no impact in younger individuals, but in those around 40 years and over, significant improvements were obtained.
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 in ageing.
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.”
*These torches were produced for the study. There are currently no commercially available torches of the same specification.
**Participants placed their eye over the end of the torch. Eyes could be closed as the red light is not filtered by the eye lid.