One thing that almost everyone experiences as they age is a decline in their vision, although a new study in the Journals of Gerontology reveals that this problem may have a surprisingly simple and affordable solution. By staring at a deep red light for just 3 minutes a day, older participants were able to significantly improve their vision.

The human retina contains two kinds of photoreceptor cells, known as rods and cones because of their respective shapes. Rods are found around the boundary of the retina and provide us with peripheral vision while also helping us see in low light conditions, while cones give us color vision.

Both types of cell have high energy demands, and receive this energy in the form of a compound called adenosine triphosphate (ATP), which is produced by their mitochondria. However, from the age of about 40 onwards, our mitochondria begin to function less efficiently, meaning less energy is available for our rods and cones and our vision subsequently starts to deteriorate.

Long-wavelength light spanning 650 to 1,000 nanometers – which has a deep red color – has previously been found to improve mitochondrial performance, which is why the study authors decided to investigate whether this could be used to restore vision in older people.

To conduct their study, the team recruited 24 volunteers aged between 28 and 72, none of whom suffered from any ocular disease. On day one, each participant was given a series of tests designed to determine how well their rods and cones were working.

Rod sensitivity was examined by asking participants to try and detect faint light signals in the dark, while cone function was determined via a color contrast test, which involves identifying colored letters against a background that is of a very similar hue.

Participants were then given a cheap LED torch that emits a deep red light with a wavelength of 670 nanometers and asked to look into it for 3 minutes a day for two weeks. This could also be done with closed eyes, as the eyelid does not filter out red light.

When eye tests were re-administered at the end of this period, participants over the age of 40 displayed significantly increased cone function, with an average improvement of 22 percent. This heightened color sensitivity was especially pronounced at the blue end of the spectrum, which was to be expected as this range of color vision is known to be particularly affected by mitochondrial decline.

Improvements in rod function were also seen, though these were less impressive. This may be because rods are known to die when their energy demands are not met, and most people lose around 30 percent of their rods by the age of 70. Cones, however, simply cease to function yet do not die, and it would appear that the red light treatment restored these cells’ efficiency.

In a statement, study author Glen Jeffrey said that the 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 also cheap to make, meaning so could be available in the not too distant future.“Our devices cost about £12 [$15] to make, so the technology is highly accessible to members of the public,” Professor Jeffery said.