The rate of nearsightedness is on the rise in the United States, according to a new report.
In a broad survey published in the December issue of Archives of Ophthalmology, researchers compared recorded vision information for more than 4,400 people tested in 1971 and 1972 with data from another set of 8,300 people tested from 1999 to 2004.
Their findings? Exactly 25 percent of people examined in the 1970s were considered nearsighted, while 42 percent of those examined in the late 1990s and 2000s were.
That's a 66 percent increase.
The severity of myopia also increased, the researchers found. The rate of moderate nearsightedness doubled and recorded severe cases, while still largely uncommon, also rose sharply.
Cases of mild myopia increased slightly, from 13 percent to 18 percent.
To ensure an accurate comparison, scientists made sure to only use technology used in the 1970s -- standard eye tests, trial lenses -- rather than alter results with the more advanced technology that was available for the second more recent data set.
What causes nearsightedness? Scientists aren't sure. Previous research has linked it to genetic predisposition as well as working excessively at near distances, such as jobs that involve tiny objects or the written word.
The logical next question: are computers and smartphones and other close-distance, eye-concentrating technology causing us nearsightedness?
Or is genetic predisposition working its way through the population?
This post was originally published on Smartplanet.com