A missing color in indoor light may help prevent myopia

New research suggests that exposure to a specific wavelength of indoor light may help prevent myopia, or nearsightedness, in children. The study, led by scientists at Cincinnati Children's Hospital and the University of Alabama at Birmingham, focused on indigo light, a short wavelength of visible light that is abundant in natural sunlight but largely absent from typical white LED lighting.

The researchers performed experiments on tree shrews, a close relative of humans with visual systems that share important similarities with human eyes. They found that exposure to indigo light, specifically between 419 and 446 nanometers, completely prevented the development of myopia in the tree shrew models. Myopia, characterized by the eye growing too long and causing distant objects to appear blurry, is becoming increasingly common worldwide, with some estimates suggesting that nearly 50% of the global population could be nearsighted by 2050.

The researchers believe that the limited presence of indigo light in modern indoor lighting may contribute to the rising rates of myopia. To test their hypothesis, they used tiny spectacles designed for tree shrews to produce a strong signal that encourages myopia in one eye, while the other eye served as a comparison. By measuring eye shape and axial length and monitoring changes in refraction over time, the researchers were able to observe the effects of different wavelengths of light on the developing eyes.

While violet light near 380 nanometers had previously been shown to reduce myopia in mice, it did not produce the same effect in tree shrews. This discovery prompted the researchers to explore slightly longer wavelengths that could still stimulate the necessary biological pathway. The findings indicate that indigo light, which can pass through the lens while activating nonvisual opsins involved in biological processes beyond forming images, could be a potential solution to prevent myopia.

The study highlights the importance of natural sunlight exposure for proper eye development and suggests that redesigning indoor lighting to better mimic the outdoor environment may help reduce the prevalence of myopia in children. However, more research is needed to determine whether indigo-enriched lighting can effectively prevent myopia in human children.