Exposure to deep red or near-infrared light can improve the function of the eye’s mitochondria, the powerhouses in cells, resulting in slight but lasting improvement to declining eyesight.

An unusual experimental treatment for fading sight involves shining a red light into the eyes for a few minutes to boost the activity of mitochondria, microscopic structures that provide energy inside cells.

In the first small test of the approach in 24 people, one short exposure to the light slightly improved people’s performance in tests of colour vision for several days.

Deep red light and near-infrared light have previously been shown to enhance the function of mitochondria in a range of cell-based and animal experiments. These wavelengths seem to work by improving the performance of key molecular structures within mitochondria, called ATP synthase pumps.