Nearsightedness is incredibly common, affecting an estimated 40 percent of Americans and up to 90 percent of young adults in Asian countries.1
According to research published in 2009, rates of nearsightedness in the U.S. have risen by 66 percent since the early 1970s.2
A 2015 study estimated up to one-third of the world's population may be nearsighted by the end of the decade — that's 2.5 billion people.3
The following year, a meta-analysis of 145 studies predicted nearly half of the world will be nearsighted by the year 2050.4
Just what might be causing this rapid mass-deterioration of vision? One longstanding theory was that excessive reading at close distance (particularly in poor lighting) could lead to nearsightedness by altering growth and shape of the eyeball.
As computers and smartphones grew in popularity, squinting at computer screens has received a majority of the blame.
The "bookworm theory" first emerged centuries ago when German astronomer Johannes Kepler claimed his studies caused his nearsightedness. It seemed plausible enough, especially as rates of the condition skyrocketed in regions like Shanghai, where teens spend about 14 hours a week on homework.5
However, once investigated further, the bookwork theory came up short
. When researchers looked at number of books read per week or hours spent using a computer among children in Singapore, no significant link to nearsightedness was actually found
According to the authors, "neither reading nor parental myopia history were associated with values for anterior chamber depth, corneal curvature, or lens thickness."
They went on to suggest that "corneal curvature and lens thickness may be subject to unrelated postnatal growth control mechanisms." Interestingly, a number of studies now suggest one of these control mechanisms might be sun exposure.