Why Is Being Nearsighted So Common? A Look Into Why Vision Changes

An expansive review of research published this week in the British Journal of Ophthalmology turned a focus on myopia, or nearsightedness, in children, finding that about one-third of kids and teens have some trouble seeing at a distance. 

The fact that rates of myopia are growing is not necessarily new information, but the latest research calls attention to how our daily lives have recentered to more time spent indoors looking at things up close to our faces — particularly during the pandemic — and strengthens the idea that this may affect young and developing eyes. 

By 2050, researchers predict that about half of the world’s population will be nearsighted. This probably isn’t a coincidence, but instead may be a result of our environment and the way our eyes are adapting to the new tasks (and books, and screens) at hand, according to Dr. Viola Kanevsky, a past president of the New York State Optometric Association. 

In addition to genetics, the reason so many of us start squinting trying to read a road sign may be because our eyes adapted to a more indoor, in-your-face environment while they were growing to their adult form and length. 

This is opposed to a person with either “perfect” vision or someone who is farsighted, who’d be much better suited to spotting danger in the distance. It’s even possible there may have been more of them back in the day, compared to the smaller 5 to 10% proportion of far-sighters these days. (Age-related presbyopia, which gives you a farsighted effect because you can’t see up close, is actually a different condition.)

“We think, partially, that’s an adaptation to our environment,” Kanevsky said last year. “The guy that survived was the guy who could see the tiger coming to eat him first.”

We aren’t doing much tiger-chasing anymore, but there are health risks associated with being farsighted or nearsighted — severely nearsighted, in particular. Here’s a closer look at what Kanevsky says it means to be nearsighted versus farsighted, how to slow the risk of nearsightedness in children and other ways our eyes may be reflecting the new world we live in.

Read more: How a Giant Eyeball Exhibit Hints We Don’t Fully Know What New Tech Will Do to Our Vision 

How nearsightedness and farsightedness develop 

There is a genetic influence to being either nearsighted or farsighted, aka hyperopic. This means that if one or both of your parents need glasses, you have a greater chance of needing them yourself. For example, if one parent is nearsighted, their child would have roughly a 30% chance of also being nearsighted, Kanevsky said. 

Anatomically, there are differences between a nearsighted and a farsighted eye. A nearsighted eye would typically be considered “longer” than a perfect eye, whereas a farsighted eye would be considered “shorter” than a typical eye. 

Most babies are born slightly farsighted, Kanevsky says, until the eyes grow to their proper length. For people who stay farsighted, vision correction may be needed to help them see closer up and reduce the risk of eye strain and crossed eyes. 

For those with myopia, it likely developed during childhood, as the eye kept growing and getting longer than what’s “normal.” The progression from a little blurry to total blur might seem inevitable, but it turns out it’s not. Nearsightedness is not reversible, but being severely nearsighted is preventable for many people.

The sweet spot of myopia 

Catching myopia right at its beginning stages may help keep people in that relative sweet spot of having vision that’s arguably better adapted to their environment, but not so myopic that they have an increased risk of eye diseases like glaucoma and retinal detachment, for which nearsighted people are already at higher risk.

This sweet spot maxes out at about 3 diopters of power, or a “negative three” prescription, according to Kanevsky. 

To control myopia, there are a few treatments cleared by the US Food and Drug Administration for kids when their eyes are still developing and children are just slightly nearsighted. Parents and teachers are in a good position to spot this — squinting to read the blackboard, for example. 

One of these methods is orthokeratology, which involves a hard lens kids put in at night and remove during the day. It works by temporarily flattening the cornea, which corrects vision for the duration of the day until you start the whole process over again the next night. This is a similar, nonsurgical method to Lasik. 

There are also specific, soft lenses for myopia control, according to Kanevsky, and are also approved by the FDA. She adds that while some eye doctors will prescribe myopia control contacts for adults, or for someone very nearsighted (i.e. over 3 diopters), she’s hesitant about flattening the cornea too much.

Another method is low-dose atropine drops used for myopia control, but only off-label, as the exact way they work isn’t clear enough yet to constitute FDA approval, Kanevsky says.

All these methods in kids are about 50% effective at reducing myopia, Kanevsky says. Growing eyes typically change about a half step per year, she says — from -2 to -2.5 in one year, for example. With intervention, it could instead change to a -2.25.  

“By intervening with these methods early on, we can slow that to a quarter step a year,” she added.

The risks of the different methods of myopia control are still being researched, but it may be worth discussing for children who are at risk of severe myopia, used in tandem with the most simple and effective way to curb myopia: spending time outdoors. Based on myopia control studies, children who spend between 80 and 120 minutes a day outside have a decreased risk of myopia developing, according to the International Myopia Institute. 

How spending more time outdoors curbs myopia growth, exactly, is a little less clear.

“Is it just because you’re looking at something farther away that the process slows, or is it actually something about full-spectrum light that you’re getting that helps the retina not stretch and not grow?” Kanevsky said, adding that being active may provide other health benefits even in adults that can also help your eye health, like lowering your blood pressure or blood sugar. 

Besides following the 20-20-20 rule, there’s no evidence that you’ll be able to significantly help (or hurt) your eyesight as an adult after they’ve reached their final form and size. Following the rule — which says to take a break from screens or up-close reading every 20 minutes, looking 20 feet away for 20 seconds — can prevent your eyes from becoming strained from too much screen time.

Age-related blurry vision is not the same thing as being farsighted 

Around midlife, people start to have some trouble seeing things up close, giving a farsighted effect. The reason why it occurs is different than regular farsightedness, resulting in an inevitable condition called presbyopia. 

In the eye we have a crystalline lens that pulls objects in and out of focus, similar to how you’d focus a manual camera, Kanevsky says. With age, that lens becomes less flexible.  

“Right around 40, that lens kind of grows like a little onion and adds layers, becomes stiffer,” she said. “Even a person who’s always had perfect vision suddenly needs reading glasses and starts to pull things out further.”

For people who are farsighted, this may happen a little sooner than people with normal vision, because their eyes are already focused on what’s in the distance, with less clarity up close. People who are nearsighted may be older before it becomes a problem, but they also eventually succumb to age-related blurriness. 

There’s no treatment, but there are things that can make short distance viewing a little easier, like reading glasses or contacts. You can also ask your doctor about these over-the-counter eye drops. Progressive lenses are another option, especially for people who already wear single-vision glasses. 

Give it a few decades (or a few hundred or thousand years), and maybe our eyes will take another shift in trend, allowing older folks the same reading-and-screening ability of the youth (sans glasses) as we live longer and become more technology-focused. Whatever the future holds, for better or worse, maybe our eyes will continue adapt to the world we live in.