For kids in Singapore, the pressure for academic success is intense. After the regular six- to eight-hour school day, many children attend extra classes at private schools and devote long hours to homework in the evening. In recent decades as study hours have expanded, so has the country's rate of nearsightedness—to epidemic proportions. An astonishing 80 to 90 percent of newly minted high school graduates in Singapore are myopic. The same is true in China, Taiwan, Japan and South Korea—all places where kids now spend far more time hunched over a desk or computer than did previous generations. Rates are rising in other developed nations as well. In the U.S., the prevalence of myopia nearly doubled from 25 percent in the 1970s to 42 percent in the early 2000s.