Children can spend hours a day looking at computer screens and other digital devices. Some eye care professionals say all that screen time has led to an increase in what they call computer vision syndrome.Nathan Bonilla-Warford is an optometrist in Tampa, Florida, with VSP, Vision Service Plan, a big insurance provider. He says, "I see a lot more children who are coming into the office either because their parents have noticed that they have headaches or red or watery eyes or discomfort, or because their prescription, their near-sightedness, appears to be increasing at a fast rate and they're worried." Dr. Bonilla-Warford says part of the problem is that children may be more likely than adults to ignore early warning signs. "Even if their eyes start to feel uncomfortable or they start to get a headache, they're less likely to tell their parents, because they don't want to have the game or the computer or whatever taken away." He says another part of the problem is that people blink less often when they use digital devices. "The average person who uses a computer or an electronic device blinks about a third as much as we normally do in everyday life." So the front part of the eye gets dry. Eye doctors offer suggestions like following what is known as the 20/20/20 rule. "Every twenty minutes, look away twenty feet or more for at least twenty seconds from whatever device you're using." Twenty feet -- that's six meters. Other suggestions include putting more distance between you and the device and using good lighting. Of course, you could also spend less time looking at screens. Many experts say children should spend no more than two hours a day using digital devices -- with no screen time for children under two. But not all eye doctors have noticed an increase in problems in children. Dr. David Hunter says he has not seen an increase in his practice as a pediatric ophthalmologist at Children's Hospital Boston. He also serves as a spokesman for the American Academy of Ophthalmology.Dr. Hunter thinks calling it a syndrome, as in computer vision syndrome, is a little much. He says the real problem is simple. "Spending too much time in one place, focusing on one thing." And while this might be tiring to the eyes, he says, "there's certainly no evidence that it actually causes any damage to the eyes."

For VOA Special English, I'm Alex Villarreal.