Screen time may be linked to myopia
INDIANAPOLIS – When her oldest child came home from school and said vision screening had revealed he would need bifocals, Kailey Welch was shocked. He was only 12.
Sure, she wore prescription lenses herself, but she didn’t start until she was well into adulthood. To her greater surprise, three of Welch’s seven other children also have needed glasses.
The likely reason, according to her doctor: devices, at home and at school.
Welch’s family represents a trend eye specialists have been watching with some alarm: a steep increase in the number of children who need corrective lenses.
Screens are an easy culprit, but experts suspect that is only part of the explanation. Exposure to sunlight may play a role. More time spent outdoors appears to ward off the need for glasses. Increased awareness among parents to have their children’s eyes screened combined with simple genetics also factor in.
But pinning down exactly why continues to vex the field.
“That’s kind of the million-dollar question now,” said Dr. Katherine Schuetz, a pediatric optometrist with Little Eyes in Indiana.
When Gen Xers were young in the ’70s, about 20% of children in the United States needed glasses. Now that number has inched closer to 40%, said Dr. David Epley, a clinical spokesman for the American Academy of Ophthalmology. Other estimates say the percentage of young people with myopia or nearsightedness is even greater, more than 45%, said Dr. April Jones, a pediatric optometrist with Riley Childrens Health.
Across the globe, researchers note that children in certain countries are more likely to wear glasses than in others. In many parts of Asia, for instance, as many as 90% of children have myopia, a study published in the Lancet in May 2012 found. By contrast, countries such as Australia boast a lower percentage of children with myopia than in the U.S.
Genetics alone cannot explain such differences. So specialists suggest it’s a combination of factors, starting with screen use.
Exposure to sunshine, however, may be just as important if not more, experts are beginning to believe. Again, it’s not clear exactly why, but natural sunlight appears to stabilize vision regardless of whether a person uses screens.
Skeptics may note that children have been reading books for centuries and that has not had as great an impact, but screens are not exactly equivalent.
In general, close work, whether staring at a screen or a book, strains eyes. When a person reads, however, he or she tends to hold the book farther away than a phone or tablet, perhaps because books are bigger.
Holding objects close to the eye flexes muscles in the eye that may wind up telling the body to grow the eyeball, Jones said. While the eyeball naturally lengthens over time and a certain amount of growth each year is expected, screen use may speed up the process, resulting in myopia.