In the 1950s, 10-20% of the Chinese population was myopic. Today, as many as 90% of children and young adults are. Over 96% of 19-year-old Korean men are nearsighted. And the problem is not confined to East Asia: 40 years ago, 25% of Americans aged 12 to 54 were myopic. Today the number has risen to 42%.
There’s no doubt that we are witnessing a huge increase in myopia around the world, and it’s not just a matter of more kids needing glasses. Early childhood myopia can lead to serious vision problems later in life, like glaucoma, macular degeneration and even retinal detachment. So what’s behind this dramatic increase in myopia?
Clearly, genetics are one factor. But genes alone can’t explain the very rapid increase in myopia, so environmental and behavioral factors must also play a role. Book work has long been considered a primary culprit. Centuries ago, Johannes Kepler, the astronomer and optical scientist, attributed his own nearsightedness to all the time he spent studying. And even today, people associate eyeglasses with intelligence (or nerdiness, especially if the bridge of the frame is taped together.) Kids who read and study more appear more likely to be myopic, and the pressure for academic achievement helps explain the high levels of myopia in China and Korea. But even before they can read, many children play with smart phones and tablets, which could be setting the progress toward myopia into motion even earlier.
However, some evidence suggests that up-close work is not the actual trigger for the eyeball to elongate. A study by the Ohio State University College of Optometry found that neither book nor computer work correlated to increased risk of myopia. The one factor that did appear to reduce the likelihood of myopia was spending time outdoors. If this is true, increased study time and is still a factor to the extent that it can mean less time spent outdoors. Other factors could include the reduction of PE programs in many schools, parents’ reluctance to let their kids play outdoors unattended, and the rise of video games as a preferred leisure activity among kids.
Results are preliminary, and more research is needed to confirm the link between outdoor time and myopia. The specific mechanism by which outdoor time prevents myopia also requires further study, but some researchers believe that sunlight plays a role. But whatever the causes, the increase in cases is real, and likely to continue.
There are a number of treatment options that have been effective in slowing the progression of myopia in children: atropine eye drops, soft multifocal contacts worn in the daytime, or rigid contacts worn at night (ortho-k). Some eyeglass-based treatments have also been developed or are in development. But none of these can compete with the natural solution – more outdoor time for kids, which of course has additional benefits for children’s health (and perhaps the mental health of their parents.)
The explosion in myopia shows that parents need to be more vigilant than ever before in detecting warning signs so the problem can be addressed through behavioral changes or treatment. These include squinting to see in the distance, holding books very close to the eye or sitting close to the TV, headaches and eye strain. Once elongated, and eyeball can never be made shorter, but it is possible to slow the progression.