Eyeglass sales are expected to double globally between 2012 and 2026, and the amount of time people are spending indoors may be a leading cause. The reason? An explosion in nearsightedness, especially in Asia, which may be linked to lack of sun exposure.
In the 1950s, roughly 20 to 30 percent of 20-year-olds in Hong Kong, Taiwan and South Korea suffered from myopia. Today, the shares are above 80 percent. In the United States, the increases have been significant though a bit less dramatic. In the early 1970s, 24 percent of 25- to 34-year-olds were nearsighted. By the early 2000s, that share had almost doubled, to 44 percent.
Some projections suggest we're not done with the rises. For example, one study from the American Academy of Ophthalmology undertakes a meta-analysis of 145 studies of the rise in myopia and then projects the increases forward based on the historical trend along with projected urbanization and demographic data. The forecast, like any mechanical projection over multiple decades, should be taken with a grain of salt — but is still startling. By 2050, half of the global population, or almost 5 billion people, are projected to be nearsighted, up from a quarter, or 1.4 billion, in 2000.