Does that 3-D image make you sick?

NEW YORK (Wall Street Journal) - If you missed the 3-D movie "Avatar" in theaters, don't worry. New TVs are coming equipped with 3-D mode and video games are also ramping up their graphics to take advantage of 3D's startling visual effects. But a national eye doctors' group is concerned about problems behind those funny glasses.

"We think its important for parents to understand why 3-D causes visual discomfort, motion sickness, or headaches for some," Christina Curas, a spokeswoman for the American Academy of Ophthalmology , said about new 3D TVs and video games.

Exhibit A is a warning released by Samsung last month about watching its new 3D televisions, the group says. Health risks include eye strain, headaches, and dizziness, according to the warning. It advises taking a break from watching if these symptoms occur.

But the chief of ophthalmology at Children's Hospital Boston isn't convinced 3D warrants concern. "We see in 3D all the time," said Dr. David G. Hunter, who is also vice chair of ophthalmology at Harvard Medical School. "Our whole world is viewed in 3D, so I am surprised there would be warnings about those things."

3D movies simulate what our eyes do by using two cameras to shoot from slightly different distances. Our brains bring the two images together from what our eyes see on the screen with the help of special glasses, giving depth to the image. Because 3D images render a less-than-perfect approximation of what our eyes do, it can be fatiguing to watch. Then there's the difference between movies or video games and real life.

"Normally you see things at various distances," Hunter said. "You don't have animals flying into your face or space balls floating all around you, this onslaught of things being thrown at you all the time in ways that wouldn't happen in real life. Also if the camera is moving in a way that's not natural, that's going to enhance it too. Even a not-3D movie, 'The Blair Witch Project,' caused a lot of people to get nauseated."

Video games may be less bothersome because it's easier for players to just take a break, Hunter said.