By the year 2050, nearly half of the planet will suffer from some degree of myopia, aka short-sightedness. One fifth of them will be at increased risk for total, permanent blindness. This is according to a study published Friday in the journal Ophthalmology by researchers at the Brien Holden Vision Institute. The authors note that the coming wave of squinters, who together will represent a fivefold increase in myopia incidence from year 2000 levels, is poised to become a major public health concern.
That short-sightedness is booming isn't exactly news in itself. Already, half of adults in the US and Europe suffer from it to some degree (doubled from 50 years ago); in China, 96 percent of 19 year old males have myopia (up from 10 to 20 percent 60 years ago). Last year, researchers from Holden calculated that a third of the planet's total population will be short-sighted by the end of the decade.
While the myopia boom is a reasonably well-studied phenomenon, research so far has been limited in two major ways, according to the Holden group. "First, individual studies suggest wide variation in the prevalence of myopia between different regions and ethnic groups," the study notes. "For example, the prevalence of myopia is more than 2 times higher among East Asians than similarly aged white persons."
"Second," the paper continues, "the prevalence of myopia in different countries seems to be increasing, and most dramatically among younger people in East Asia. The combination of vision impairment from uncorrected myopia and irreversible vision loss from myopia-related complications make accurate global estimates of the prevalence and temporal trends critical for planning care and services. However, there are no precise estimates of the global prevalence of myopia or for projected temporal changes over the next few decades."
"The prevalence of myopia in different countries seems to be increasing, and most dramatically among younger people in East Asia."
This is where the new work comes in. The study offers a systematic review of the prevalence of myopia and high myopia using data published since 1995. 1656 papers on myopia and 2632 papers on refractive error (the general class of vision problems that myopia is a part of) were located and analyzed. Together, they offer a fairly high-resolution view of the global myopia boom over modern times. It's a bad scene, but one unlikely to change given the state of things.
And what is the current state of things, in terms of eye health? A lot of people staring at screens and a lot of people that don't spend enough time outdoors. "The projected increases in myopia and high myopia are widely considered to be driven by environmental factors (nurture), principally lifestyle changes resulting from a combination of decreased time outdoors and increased near work activities, among other factors," the authors report.
Of particular concern are countries like China, Taiwan, Singapore, which increasingly feature "high pressure educational systems" from a very young age. "[This] may be a causative lifestyle change, as may the excessive use of near electronic devices," the paper concludes.
It's a tricky thing. Technology giveth and technology taketh. I myself just started wearing glasses recently because of mild but recent myopia, and, boy howdy, do I spend some time in front of a screen. But I also spend a fair amount time outside in natural light, which is a good thing eye-wise, so it could probably be worse.
According to Nature News, Ian Morgan, a myopia researcher at the Australian National University, has estimated that children need to spend around three hours per day under light levels of at least 10,000 lux to be protected against myopia. That's about the level experienced by someone in the shade on a bright summer day while wearing sunglasses. A 2013 study, meanwhile, found that students in Taiwan who were required to spend their 80 minute breaks outdoors rather than inside had an incidence of myopia of 8 percent compared to 18 percent at a nearby school. In other words, this is a problem that can be solved easily enough.