Probably not, though there’s no hard proof.

“In theory, we do think that the more you use your eye muscles and the visual processes in the brain, the more likely you are to develop nearsightedness, especially at a young age,” said Dr. Sandra Cremers, an ophthalmologist at the Massachusetts Eye and Ear Infirmary. And there are animal studies suggesting this effect does occur. “But when we do randomized controlled studies in people, we don’t find it an issue,” she said. “There is controversy in this area.”

“I don’t see any clinical evidence in the last 10 or 20 years that young people who spend more hours at the computer require glasses more often than anybody else,” said Dr. Elliott Myrowitz, an optometrist and assistant professor of ophthalmology at the Wilmer Eye Institute at Johns Hopkins School of Medicine.

Teenagers, like older people, who spend long hours at the computer do report more eye fatigue, Myrowitz said, as well as more muscle strain in the eyebrow area. But teens who stare at computer screens for long periods “are not ruining their eyes,” he added.

As for staring at a bright computer in a dark room? Not to worry. “Young people have very good contrast sensitivity,” Myrowitz said, unlike their elders who do have more trouble focusing when they shift rapidly from light to dark environments.

And there’s more good news. “There’s no proof that watching TV up close in a dark room is bad, either,” said Cremers. As a matter of common sense, though, she does advise teens and adults to “have as good light as possible.”