For many years, scientists believed myopia — more commonly known as nearsightedness — was written into your genes. But as rates of the condition increased worldwide, more researchers began looking for the environmental causes behind blurred perception of far-away objects. Now, a new study bolsters the theory, showing a correlation between education level, years spent in school and increased risk of nearsightedness.

The study, conducted by researchers at the University Medical Center in Mainz, Germany, examined the eyes, genes and education of 4,658 German subjects. While only 24 percent of those without a high school degree suffered from myopia, 53 percent of university graduates had myopia. “Participants with higher educational achievements more often were myopic than individuals with less education,” the authors wrote in the journal Ophthalmology this month.

The implication is that burying your face in a textbook or computer monitor strains the eyes. Myopia happens when light from far-away things focuses incorrectly on the retina at the back of the eyeball. Causes of that could be an elongated eyeball or a cornea — the front covering of the eye — that curves too much.

While this new study is the first to name book-learning as the culprit, several others in recent years have supported the idea that myopia is more often acquired than inherited. In 2012 in Taiwan, researchers noticed that schoolchildren were less likely nearsighted if they spent more time in outdoor recess. That same year, a study in Denmark suggested that exposure to daylight lowered the risk of myopia in children. “The antidote to the rise in myopia could be as simple as going outside more often,” the American Academy of Ophthalmology recommends.

As of 2004, about 42 percent of Americans were nearsighted, according to one study. That’s compared with just 25 percent of the population in the early 1970s. This statistic alone was enough to suggest that environmental factors play a heavier hand in myopia than genes. And among all populations, experts say, kids are the most vulnerable as their eyes develop up to the age of 20. "Since students appear to be at a higher risk of nearsightedness, it makes sense to encourage them to spend more time outdoors as a precaution," said Dr. Alireza Mirshahi, lead author of the new study.

Source: Mirshahi A, Ponto KA, Hoehn R, et al. Myopia and Level of Education. Opthalmology. 2014.