Red Light Improves Vision of Aging Eye

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Over the last decade, neuroscience research has revealed that slowly progressing vision deficits can occur in otherwise normal eyes because of age-related declines in the number and functionality of photoreceptor mitochondria. In a recent study, re­searchers found that this phenomenon can be tempo­rarily reversed by a single three-minute exposure to deep red (670 nm) light.¹

“The retina has more mitochondria than any oth­er part of your body, and they have distinct optical characteristics,” said study leader Glen Jeffery, PhD, at University College London’s Institute of Ophthal­mology. “Short wavelengths—deep blues—reduce the amount of energy that mitochondria produce. But long wavelengths, like the deep red we used in our study, improve mitochondrial function.”

Study specifics. Dr. Jeffery’s group used a specially modified LED flashlight to deliver a single three-minute dose of the deep red light unilaterally to the retinas of 20 subjects (age range, 38-70 years).

The researchers found that cone-mediated color contrast thresholds in the treated eyes improved to acuity levels normally found in younger adults—and that the improvements persisted for one week. The thresholds significantly improved by mean levels of 17% (blue-yellow axis) and 12% (red-green axis; both p < .0001). However, the visual gains from the treatment only occurred if the light exposure was provided in the morning.

The research group hypothesizes that exposure to the deep red wavelength increases the impaired mito­chondria’s energy production by reducing the viscosity of water surrounding the rotating mitochondrial pumps that generate adenosine triphosphate, thus improving their efficiency.

It is possible that the pumps gain greater momen­tum and that this is sustained for a period, Dr. Jeffery said. “But as with a lot of mitochondrial research, there is much we do not know,” he said.

Next steps. The researchers are planning further clinical studies aimed at understanding the temporal difference that emerged in the results. They also are seeking to optimize the treatment parameters to achieve longer-lasting effects while maintaining the safety of the light exposures.

Dr. Jeffery said he hopes his studies will help address important quality-of-life issues posed by mitochondrial dysfunction as retinas age. With further research, it might become apparent, for instance, that the virtual nonexistence of long wavelengths in much of today’s indoor lighting is preventing optimal vision in the elderly, he said.

—Linda Roach

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1 Shinhmar H et al. Sci Rep. 2021;11(1):22872.

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Relevant financial disclosures: Dr. Jeffery—None.

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