How far can you see?
More than 32 percent of the world’s population has myopia, or nearsightedness, according to a 2019 study in the Investigative Ophthalmology and Visual Science journal. The study predicts that by 2050, almost 60 percent of the global population will have some level of myopia, predominantly in developed countries.
The highest levels of myopia exist in urban Asian cities like Singapore, Hong Kong and Guangzhou, China. Since 2000, however, cases have increased by almost 14 percent in the U.S. and almost 15 percent in western Europe.
“Myopia has become an epidemic,” Dr. Fuensanta Vera-Diaz, an associate professor at the New England College of Optometry, told me. “The prevalence is so high and it will continue to be higher if we don’t do anything about it.”
Myopia is the rapid elongation of the eyeball, which, at best, leads to blurred vision when viewing objects that are far away. It tends to develop in childhood, with most myopic children being diagnosed between ages three to 12, according to the American Optometric Association.
For a long time, the medical community more or less accepted that patients could simply wear glasses or contacts and move on with their lives, said Vera-Diaz. However, recent studies found that myopia greatly increases chances of debilitating diseases like cataracts, glaucoma, myopic maculopathy, retinal detachment, some of which can lead to blindness.
There is no cure for myopia. Glasses, contacts, and LASIK surgery can correct vision but cannot reverse eyeball elongation. Myopia is rated in levels of mild to high, and all levels are increasing, careening some children toward semi-blindness even faster.
“I have been practicing for 15 years now and my general impression is that I am seeing more of [myopia], and it’s not just the mild amounts,” Dr. Aaron Miller, an eye surgeon in Houston and clinical spokesperson for the American Academy of Ophthalmology, told me. “I’m also seeing more kids between who started off with a mild amount, but the progression occurs more quickly.”
Doctors agree that genetics play a role in determining someone’s vision. If Sally’s parents are genetically myopic, she is predisposed to be myopic, too. Right now, it is impossible to say with scientific certainty why Sally has myopia versus her myopic buddy Joe, whose parents’ vision is fine. There is no exact test that determines cause in individuals; we can only recognize global trends and draw correlations.
A common culprit for the increase in myopia among children is something you have probably guessed: screen time. According to a 2018 American Optometric Association study, four in five parents say their kids spend at least an hour a day in front of a computer or mobile device. Miller argued that parents tend to grossly underestimate how much screen time their school-age child is actually getting. Doctors say that the constant up-close interactions might be leading to an elongation of the eye.
Screen time is a common culprit for the nearsightedness surge.
“We’re teaching kids to use tablets and devices, up close and more often,” said Dr. Barbara Horn, president of the American Optometric Association. “There are lots of studies evaluating it right now. We’re looking forward to more results.”
However, in the U.S., the surge in myopia began earlier than 1999, long before smartphones or round-the-clock device use for children, Vera-Diaz argued.
In fact, most existing studies blame the fact that kids don’t go outside as much as they used to.
While no nation or ethnicity is immune, myopia has had a head start in regions of East and Southeast Asia where, for decades, students have spent almost 10 hours in school, followed by three hours of homework. In the U.S., school days are about seven hours long, followed by about one to three hours of homework. Their “near-work” skills might be causing the elongation of eyes. These skills include screen time, but also homework and reading.
“[Students’] eyes are not developed yet and they are undergoing this competitive education inside. There is no doubt that this is affecting their vision,” Vera-Diaz said. “What we are seeing affects how the eye develops. We know this from animal models.”
While we don’t know exactly how outdoor time translates to myopia prevention, but one theory is that exposing the eye to brightness keeps it sharp. Even a gray, rainy day produces 10 times more luxes, or brightness units, outdoors than indoors, according to Dr. Donald Mutti, professor at the Ohio State University College of Optometry.
“The theory is that that bright light stimulates specialized cells in the retina to produce more dopamine, which may slow the growth of the eye,” Mutti said. “It might pump the breaks on the process that’s driving kids’ eyes toward nearsightedness.”
Vera-Diaz said that other nuanced processes outdoors might help slow eye growth, including exercising farsightedness, peripheral stimulus, and the interplay between central and peripheral vision.
One 2017 Chinese study tried to replicate the outdoors by installing glass walls on four sides of a classroom. The results were inconclusive regarding myopia.
“To be honest, just get outside,” Vera-Diaz said.
If a child is genetically myopic, outdoor time likely won’t do much to slow progression, according to Mutti. But for kids who may develop myopia due to environmental causes, he recommended two hours a day, or 14 hours a week outside. By the time kids are 12, it’s likely too late to stem the tide, Mutti said. In fact, the earlier the better.
To slow the progression of myopia in children, the FDA recently approved the MiSight contact lens, which is a multifocal typically used in older adults. Other treatments show promise, such as eye drops with a low dose of a chemical called atropine, and orthokeratology lenses, which would reshape the cornea while the child is sleeping.
“To be honest, just get outside.”
Miller recommended consistent eye exams, and involving an ophthamologist in a child’s myopia treatment early on.
Unfortunately, the treatment and repercussions of myopia cost a lot of money. In the U.S., myopia is more expensive than congestive heart failure, lung and breast cancer, according to a 2018 study. Poorer communities stand to be affected, according to Miller.
“There are the uninsured, and awareness is an issue,” said Miller. “And also these children have to depend on someone to bring them to the appointments and they’re at the mercy of their parents or caregiver. Some individuals who are in communities where they’re underserved don’t have that kind of advocate for them.”
Are we sprinting toward a near-future where everybody is blind and dependent on artificial intelligence? Or a dystopia where poorer people go blind and untreated, while the rich have control over all the seeing-eye robots and self-driving cars?
Doctors hope that prevention will win out, because we are certainly not prepared for that type of future. So much about myopia still remains a mystery.
“Even some of the treatments that we are using, we don’t completely understand how they work. We’re hypothesizing how they work,” said Miller. “There is certainly a concern that our eye health is in great jeopardy.”