Light pollution: the possible consequences of excessive illumination on retina

Abstract

Light is the visible part of the electromagnetic radiation within a range of 380-780 nm; (400-700 on primates retina). In vertebrates, the retina is adapted to capturing light photons and transmitting this information to other structures in the central nervous system. In mammals, light acts directly on the retina to fulfill two important roles: (1) the visual function through rod and cone photoreceptor cells and (2) non-image forming tasks, such as the synchronization of circadian rhythms to a 24 h solar cycle, pineal melatonin suppression and pupil light reflexes. However, the excess of illumination may cause retinal degeneration or accelerate genetic retinal diseases. In the last century human society has increased its exposure to artificial illumination, producing changes in the Light/Dark cycle, as well as in light wavelengths and intensities. Although, the consequences of unnatural illumination or light pollution have been underestimated by modern society in its way of life, light pollution may have a strong impact on people's health. The effects of artificial light sources could have direct consequences on retinal health. Constant exposure to different wavelengths and intensities of light promoted by light pollution may produce retinal degeneration as a consequence of photoreceptor or retinal pigment epithelium cells death. In this review we summarize the different mechanisms of retinal damage related to the light exposure, which generates light pollution.

Figure 1

Effect of Light Pollution on retina. Photoreceptor cells, retinal pigment epithelium, and intrinsically photosensitive retinal ganglion cells could be affected by high or prolonged low-light exposure, promoted by light during the night or indoor artificial illumination with high irradiance. These events may affect the general retinal physiology or accelerate some genetic diseases ending in blindness. These phenomena called light pollution is promoted by the customs of modern life where the human society had changed the natural circadian ld cycle. Furthermore, as a consequence of photoreceptor cells' death (cone, rod, and intrinsically photosensitive retinal ganglion cells); light pollution could have effects on the pineal organ, producing desynchronization of the circadian system, malfunctions in pupillary light reflex, and metabolic dysfunctions endangering human health. R, rods; C, cones; H, horizontal; B, bipolar; A, amacrine; ipRGCs, intrinsically photosensitive retinal ganglion cells; RPE, retinal pigment epithelium.