It also reduces the pace of age related cell death in the retina 10. Hence, regenerating aged cone function is vital because in an environment where artificial lighting results in humans rarely being fully dark-adapted and needing their rods, cone function becomes critical.Įxposure to long wavelength light (650–900 nm) in animals improves mitochondrial function, increasing ATP production and reducing ROS 8, 9. Subsequently 30% of central rods progressively die, and while cones remain, they have reduced functionality 4, 5, 6, 7. A pivotal point in their functional ageing in the human retina appears to be around 40 years 3. Retinal photoreceptors have the greatest mitochondrial density and metabolic demand in the body and age rapidly 2. Cellular decline is further accelerated with ageing by increased production of pro-inflammatory reactive oxygen species (ROS) 1. Mitochondrial membrane potential, however, declines with age resulting in reduced adenosine triphosphate (ATP) production, which is a major source of cellular energy. Metabolic rate and ageing are both regulated by mitochondria. This intervention, demonstrated to improve aged mitochondrial function can be applied to enhance colour vision in old age.
In environments with artificial lighting humans are rarely dark-adapted, hence cone function becomes critical. But light needs to be delivered at specific times. We show here that single 3 min 670 nm exposures, at much lower energies than previously used, are sufficient to significantly improve for 1 week cone mediated colour contrast thresholds (detection) in ageing populations (37–70 years) to levels associated with younger subjects.
Recently, repeated 670 nm exposures have been used on the aged human retina, which has high-energy demands and significant mitochondrial and functional decline, to improve vision. The likely mechanism is via long wavelengths reducing nanoscopic interfacial water viscosity around ATP rota pumps, improving their efficiency. However, animal studies show that long wavelength exposure (650–900 nm) over weeks partially restores ATP and improves function. Mitochondrial decline in ageing robs cells of ATP.