Indigo Light Exposure Prevents Nearsightedness in Tree Shrews
A study found that indigo light, scarce in standard indoor LEDs but common in sunlight, completely prevented myopia in tree shrews. The research suggests that redesigning indoor lighting to include this wavelength could reduce childhood myopia. The findings were published in Cell Reports Medicine.
The study used tree shrews because their ocular anatomy closely mirrors human eyes, including lenses that block ultraviolet wavelengths below roughly 400 nanometers. This distinction mattered because earlier mouse experiments pointed to violet light near 380 nanometers as protective, but that wavelength cannot reach the shrew retina. Indigo light, by contrast, falls within the visible spectrum and penetrates the lens effectively.
Researchers induced myopia in one eye using custom miniature spectacles, then measured axial length and refractive changes with a biometer and autorefractor. The protective effect was absolute under indigo exposure, even against a deliberately strong myopia stimulus. This suggests the mechanism may involve opsin 5 receptors, though the team has not yet confirmed that pathway in shrews.
If replicated in humans, this finding could reshape indoor lighting standards for schools, homes, and workplaces, potentially slowing the global rise in childhood myopia. Families and pediatricians may gain a simple, non-invasive preventive tool, though long-term safety and optimal exposure durations remain unknown. The impact could be substantial, given that half the world’s population may be nearsighted by 2050, but clinical translation will require careful trials before any public health recommendations emerge.