Deep red light improves declining eyesight
New research from the University College of London (UCL) has found that declining colour vision — which happens as we age — can be improved by an average 17% when we’re exposed to deep red light. The treatment, which takes just three minutes, works when given in the morning and benefits last a week.
The research team, which published its findings in Nature, is now working with a lighting company to develop an affordable LED device for people to treat themselves at home.
As we age, our lenses become less flexible, making it difficult to focus on close objects, a condition known as presbyopia. The standard solution is reading glasses. We also experience reduced pupil size because the muscles that control size lose strength over time. This reduction, called miosis, explains why people in their 60s need three times more ambient light to read by than people in their 20s. The standard solution is to sit near a lamp. Miosis also explains why older people are dazzled by light and glare when emerging from a darkened room into sunlight. The standard solution is spectacles with photochromic lenses and anti-reflection coating. Also as we age, we naturally lose colour perception and contrast because cells in the retina decline in sensitivity, causing colours to become less bright and the contrast between different colours to be less noticeable.
It’s this loss this new therapy aims to reduce. Our colour vision requires a lot of energy, which is produced in our cells by its powerhouse, the mitochondria. This is why mitochondrial density is at its greatest in the retina’s photoreceptor cells — more than anywhere else in the body.
And it’s why the retina ages faster than other organs. This generally begins after the age of 40, when the mitochondria produces less adenosine triphosphate, a major source of cellular energy. As a result, 30% of the retina’s central rods progressively die, and while cones remain, they have reduced functionality. The good news is mitochondria have specific sensitivities to long wavelength light, influencing their performance.
The researchers found exposing people to longer wavelengths spanning 650 to 900 nanometres (nm) improves mitochondrial performance. In the study, 20 human volunteers, aged between 34 and 70, were exposed to 670nm wavelength deep red light for three minutes between 8am and 9am; 670nm is the exposure point that effectively switches on the retinal mitochondria.
The colour vision of the participants was then tested again three hours later and 10 of them were also tested a week later. On average, there was a ‘significant’ 17% improvement in colour vision, which lasted a week; in some older participants there was a 20% improvement, also lasting a week.
“Using a simple LED device once a week recharges the energy system that has declined in the retina cells, rather like recharging a battery,” says lead author, Professor Glen Jeffery.
Morning exposure was “absolutely key” to achieving improvements in declining vision. From their work on flies, the researchers learned that mitochondria have “shifting work patterns and do not respond in the same way to light in the afternoon”.
“This simple intervention applied at the population level would significantly [improve] quality of life as people age and would likely result in reduced social costs that arise from problems associated with reduced vision,” Jeffery adds.