PLANET OF THE NEARSIGHTED: The World Faces a Myopia Epidemic

Aliens by Yurii Musatov / facebook.com

Why are modern children becoming increasingly nearsighted, what role does lifestyle play in this trend, and is it possible to stop — or even reverse — the process? These questions are now at the forefront of ophthalmic research worldwide. A review published in Nature brings together the latest scientific evidence on the causes of the rapid rise in childhood myopia, the mechanisms behind its development, and the most promising strategies for prevention and treatment — from spending more time outdoors to innovative optical and pharmacological approaches.

MYOPIA: A LEGACY OF COVID-19

he COVID-19 pandemic changed not only the way children learn but also the way they see the world. It began altering them at an anatomical level, reshaping the very structure of their eyes. As classrooms and playgrounds gave way to virtual lessons and digital devices, children spent increasing amounts of time focusing on screens and other nearby objects. With far fewer opportunities to spend time outdoors, they rarely needed to look into the distance. As a result, children’s eyeballs began to elongate, adapting to the demands of prolonged near vision. The findings were striking. Ophthalmologists in Hong Kong reported that, compared with pre-pandemic levels, the number of six-year-old children with pathologically elongated eyeballs nearly doubled. While corrective glasses were prescribed to restore clear distance vision, they did not address the underlying problem. Severe myopia carries a high risk of serious complications, including retinal detachment, macular degeneration, glaucoma, and even irreversible blindness.

A PLANET OF THE NEARSIGHTED

Naturally, the number of people with myopia had been increasing long before the pandemic. Forecasts made in the mid-2010s predicted that the prevalence of myopia would double over the following 40 years, with roughly half of the world’s population expected to be affected by the middle of the century. Today, however, even those bleak projections appear overly optimistic. Current trends suggest that, rather than doubling, the number of people with myopia may triple over that period. How can such an epidemic be countered? In short, the simplest and most effective step parents can take is to ensure their children spend substantial time outdoors every day — especially during the years when structural changes in the eye are most likely to occur. Research shows that even one additional hour outdoors each day can significantly reduce the risk of developing myopia. Yet finding that extra hour is increasingly difficult in societies that place a strong emphasis on academic achievement or in densely populated urban areas where access to green spaces is limited. If returning children to the outdoors proves challenging, perhaps the outdoors can be brought to them instead. Researchers have experimented with a wide range of solutions, including glass-walled classrooms, specialized lighting systems, nature-themed wall coverings, and light-emitting glasses. Some approaches showed modest benefits, although most produced only limited results.

STOP SIGNALS

As the human body develops, the eyes continuously adjust their shape in response to specific visual cues. If the eyeball is too short, it elongates to bring objects into focus. Conversely, when it becomes excessively elongated, the eye receives biological “stop” signals. Exactly where these signals originate, however, remains a matter of scientific debate. Studies involving monkeys, tree shrews, and chickens — animals regarded as classic models for myopia research — have shown that dopamine levels in the back of the eye may rise as ambient light intensity increases. According to another hypothesis, however, the benefits of spending time outdoors are not solely due to brighter light but also to the unique visual characteristics of open environments. Natural landscapes typically offer a wide variety of visual scenes. Their elements are viewed over long distances and contain an abundance of fine detail that blends into a uniform visual image. Researchers suggest that this visual uniformity may help suppress the elongation of the eyeball: once the retina receives a properly focused image, the biological stop signal is triggered.

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DIFFERENT ENVIRONMENTS, DIFFERENT VISION

Open outdoor environments provide bright sunlight, rich visual stimulation, and increased physical activity. Indoor spaces, by contrast, are fundamentally different. Homes and offices are filled with cluttered objects positioned at varying distances and enclosed by flat walls that typically lack visual detail. Such surroundings require the eyes to constantly readjust their focus, depriving the retina of the stop signals needed to regulate eye growth. Unfortunately, modern children increasingly prefer indoor activities to walks in the park. Taiwan sought to reverse this trend by launching the “Tian-Tian 120” initiative in 2010. By encouraging children to spend 120 minutes outdoors every day, the government succeeded in halting the rise of myopia across the population. Although the pandemic did lead to a temporary increase in myopia cases, the surge was far less pronounced than in many other Asian countries. The program may also have produced unexpected benefits: according to international assessments in mathematics, reading, and science, Taiwanese schoolchildren ranked among the best in the world.

RECREATING THE OUTDOORS

Many other countries, however, have been reluctant to follow Taiwan’s example, favoring clinical treatments or artificial simulations of outdoor environments instead. In northeastern China, for instance, the prevalence of myopia among schoolchildren reportedly fell from 10% to 4% in just one year after the introduction of “bright classrooms” equipped with high-intensity lighting and reflective materials such as glass and steel. The concept was ultimately deemed impractical because of its high cost and resource demands. A far less expensive alternative — delivering light directly to the eye — is now attracting increasing attention. Australian researchers have developed specialized glasses that reproduce part of the natural solar spectrum. Meanwhile, German scientists have created a virtual reality headset that directs short-wavelength blue light into the eye’s blind spot — the region of the retina where the optic nerve exits. In theory, this means vision therapy could take place while playing video games. Japanese and American ophthalmologists are experimenting with violet light, while Chinese researchers are investigating red-light therapy, recommending exposure twice a day.

KEEPING OUR EYES ON THE HORIZON

Not all light-based approaches are considered equally safe. Simulating natural landscapes indoors, however, is unlikely to pose any risk to eye health. By drawing inspiration from nature, it may be possible to recreate visual environments that promote healthy retinal focusing. Simple measures could include painting skies on classroom ceilings or decorating school walls with large photographs of parks filled with trees, animals, and birds. Researchers are expected to publish a study comparing the eyesight of children who learned in conventional classrooms with those taught in these “nature-inspired” environments. According to preliminary reports, children in the latter group developed myopia significantly less often. Even so, the simplest, least expensive, and most reliable way to preserve healthy vision remains direct exposure to the real natural world. If humanity hopes to halt the global myopia epidemic, there is ultimately no true substitute for time spent outdoors.

Original research: