Half the World’s Population Will Be Nearsighted by 2050. Scientists Found a Life-Changing Fix.

3 min readHere’s what you’ll learn when you read this story:In a study of near-primate animals, scientists prevented myopia using indigo-wavelength light.Tree shrews have lenses and vision development that are analogous to humans in some studies.Indigo is a short-wavelength light near violet, close to invisible ultraviolet light.In newly published research, scientists found that a certain wavelength of the visible spectrum of light was responsible for preventing tree shrews from developing nearsightedness. Though “tree shrew” may bring up images of tiny rodents, the name is a bit of a misnomer. These mammals are closely related to primates, with eyes that make them ideal for studying myopia, the technical term for nearsightedness. This new research does not yet have concrete applications, but it’s an important step in that direction.Myopia is extremely common. In their paper, published now in the peer-reviewed journal Cell Reports Medicine, the authors note that 2.8 billion people have myopia today, with an expected “myopia boom” of 4.8 billion people by 2050. This vision change is very treatable, but it also seems like something in our human environment is causing the boom, and many people in the U.S. and around the world don’t have access to affordable glasses and other vision healthcare. Prevention is the best medicine when it comes to environmental factors that we can control.Fittingly, the seven researchers anchored at Cincinnati Children’s Hospital are primarily pediatric ophthalmologists, since myopia typically emerges in childhood. It takes hold during our earliest years as our lenses grow and change, and we are “typically born hyperopic,” the researchers explain, meaning farsighted. Indeed, our eyes are quite undercooked when we’re born, and babies’ eyes rapidly adjust, change, and begin to focus.As we grow up, our eyes respond to stimuli and, ideally, end up in a balanced adult shape that can see both near and far. But when the stimuli are not balanced—and scientists don’t yet completely understand the factors in this balance—then our eyes can keep elongating, sharpening near objects while distance blurs. Tree shrews have this mechanism in common with humans. In their experiment, the scientists gave the tree shrews glasses with one myopia-inducing lens while leaving the other eye free to develop normally, as a control.In wide-spectrum white light, the scientists studied the tree shrews’ lenses to see which wavelengths in particular were making it through. In human lenses, there’s a threshold around 400 nanometers of wavelength that scientists think may be important to maintaining whole vision. In the past, scientists studying mice found that ultraviolet-A (UVA) light, which is below 400 nm and outside the visible spectrum, helped stave off myopia. But in their tree shrew research, the scientists found the same type of clustered data just over the line at around 435-440 nm.This is the indigo zone of the visible spectrum, between violet and blue. To test their observation, the scientists added indigo light supplementation to the broad-spectrum white light. “[I]ndigo wavelength supplementation completely suppressed refractive change in response to the [myopia inducing] lens and produced eyes [...] almost identical to that of controls. Indigo wavelength supplementation also eliminated the exaggerated axial elongation of induced myopia,” they concluded.Because tree shrews are “near primates,” whose eyes have more in common with ours than those of mice, these results suggest that the same findings could apply to humans. Myopia is treatable, and many people already have it, but it’s still not ethical to induce it in humans or to give children an ineffective control lens.However, it’s possible we don’t need to do anything on the individual level at all. That’s because, the scientists explain, “the indigo light that provides 100% efficacy in myopia suppression is poorly represented in the spectral power distribution of the fluorescent lights and warm white LEDs that are mainstays of the lighting industry.”That means, like fluoride in drinking water or iodine in table salt, a public health change could be as simple as boosting an existing product already used in schools and public places.Caroline Delbert is a writer, avid reader, and contributing editor at Pop Mech. She's also an enthusiast of just about everything. Her favorite topics include nuclear energy, cosmology, math of everyday things, and the philosophy of it all.