Myopia - or nearsightedness - is a common condition that affects around 42% of all Americans. Now, new research suggests that higher levels of education and more years spent in school are linked with a greater prevalence and severity of the eye condition.
The research is published in Opthalmology, the journal of the American Academy of Opthalmology.
According to the organization, nearsightedness is a refractive error, whereby the eye does not bend or refract light correctly, causing close objects to look clear but distant objects to appear blurred.
Though the condition is common, the researchers - led by Dr. Alireza Mirshahi of the University Medical Center in Mainz, Germany - say nearsightedness has become even more common around the world recently, making it an increasing global health and economic worry.
For example, in developed Asian countries, myopia rates have increased to nearly 80%, and the researchers say this rapid increase suggests environmental factors may be to blame.
To further investigate the relationship between nearsightedness and environmental factors, the researchers examined 4,658 Germans with myopia who were between the ages of 35-74, after excluding any subjects with cataracts or anyone who had refractive surgery in the past.
Nearsightedness gets worse for every additional year of school
Their work is known as the Gutenberg Health Study and is the first population-based study to show that environmental factors outweigh genetics when it comes to myopia development.
Nearsightedness increases as education levels increase, researchers say.
Overall, their results show that as education level increased, myopia became more prevalent.
In detail, they found that 53% of university graduates were nearsighted, compared with 35% of high school graduates and 24% of subjects without a high school education.
Additionally, the team observed that people who spent more years in school were more myopic, with nearsightedness getting worse for every additional year of school. After looking at the effect of 45 genetic markers, they found them to be a much weaker factor in nearsightedness, compared with education level.
As a result of their findings, Dr. Mirshahi says children and young adults should be encouraged to go outside more often:
"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."
Furthermore, the team notes that recent studies of children and young adults in Denmark and Asia have shown that the more time spent outside exposed to daylight, the less the prevalence and severity of nearsightedness.
Just last month, the American Academy of Opthalmology released two new studies that added to the growing evidence that spending time outdoors may help prevent or minimize nearsightedness in children.