(Inside Science) – When most people picture a stereotypical nerd, they think of glasses and a pocket protector. Turns out there may be some truth behind that idea.
New research suggests that number of years of study is more important than genetics in whether or not a person becomes nearsighted.
A study of 5,000 German residents found that individuals with more years of schooling were more likely to be nearsighted – and were more severely nearsighted – than people with less education.
The study, published online in the journal Ophthalmology, found that education level was more important than genetics in predicting whether a person would develop myopia or nearsightedness. Both words describe a vision condition where distant objects are blurry.
"We are surprised because about 50 years ago myopia was thought to be almost completely determined by genetics," said Alireza Mirshahi, an ophthalmologist and researcher at the University Medical Center Mainz in Germany. "We see that genetic factors do play a role but the role of environmental factors is much more important."
Nearsightedness usually develops during elementary and secondary school. Studies dating all the way back to the late 1800s and early 1900s have linked myopia to higher education and activities that require focus on nearby objects, such as reading or sewing. But the root cause of myopia is still a topic of speculation among scientists.
A 2009 study found that in the United States nearsightedness had risen from 25 percent of the population to about 41 percent during the past four decades. The condition has reached almost epidemic proportions in certain East Asian countries where up to 90 percent of older schoolchildren have myopia. The rapid rise hints that lifestyle, instead of genetics, may be to blame.
The trend is concerning because eye appointments, prescription glasses and laser surgery cost time and money for affected individuals.
In the study, the researchers analyzed data from the Gutenberg Health Study, a large-scale research project looking at different aspects of health in German citizens, aged 35 to 74. Any participant who had not undergone corrective vision surgery received an eye exam and then the results were compared based on age, sex and education level.
The German school system provides a unique opportunity to look at education and nearsightedness. Students pursuing a trade can attend school for nine or 10 years, while students heading to university stay for 13. Researchers found that each additional year of schooling increased the person’s risk of being nearsighted. Of adults who completed nine years of school, about 27 percent were nearsighted, compared to about 41 percent of adults who finished 10 years. Fifty percent of participants who graduated after 13 years had the condition.
Not only were adults with more education more likely to be myopic, but, on average, they were more severely myopic than adults with less schooling.
But Mirshahi stresses that the study does not necessarily say that education is what warps the eyes. It can only find associations between length of schooling and nearsightedness.
"It doesn’t mean that someone who is not myopic is bad at school," he said.
"I think it’s very interesting," said Nina Jacobsen, an ophthalmologist and researcher at Glostrup University Hospital in Copenhagen, Denmark. "It confirms the knowledge of what other studies have shown that there is this relationship between the length of education and the development -- and also to some degree the level -- of myopia."
In about 3,600 of the participants, researchers also looked at whether or not they carried certain gene types related to myopia. But compared to the number of years spent in school, a person’s genes had only a small effect on vision.
The authors noted that they could not measure how much time each person spent outside. Some previous research suggests that outdoor exercise appears to protect the eyes from becoming nearsighted.
"Several studies around the world have shown that we are getting more and more myopic," said Mirshahi. "At the same time we are doing more and more near work. So it means spending more time reading, or looking at a computer or at a laptop or a smartphone may or probably will increase the chance of getting more nearsighted."
But not all scientists agree that our smartphones will skew our vision.
"The jury is really out on exactly what kinds of near work would put you higher risk than others," said Susan Vitale, an epidemiologist at the National Eye Institute in Bethesda, Maryland. "But I think almost everybody agrees that it would be good for kids to spend more time outside."
In future research, Mirshahi aims to test the connection between intelligence and nearsightedness. An earlier study conducted by Jacobsen found that myopic young men scored better on IQ tests than men with normal vision. The next study may show whether smart people just happen to be more nearsighted, or whether smart people are more likely to spend more time studying, which may lead to a prescription for glasses.
Though the glasses stereotype might hold true, there's still no word yet on whether more education increases the chances of wearing a pocket protector.
Patricia Waldron (@patriciawaldron) is a news intern at Inside Science.
Reprinted with permission from Inside Science, an editorially independent news product of the American Institute of Physics, a nonprofit organization dedicated to advancing, promoting and serving the physical sciences.