Despite Nintendo's recent warning that children ages 6 and younger shouldn't play games in 3-D mode on the company's upcoming 3DS portable video game system, eye doctors say parents shouldn't be overly concerned that their kids' eyesight could be damaged by the toy.

"This is just a precaution by Nintendo," said Martin Banks, an optometry and vision science professor at University of California, Berkeley. "No one's shown anything that this is a direct concern for kids less than 6 years of age."

Nintendo recently posted a warning on its Japanese website that playing games on the device might make some people feel sick, and could be dangerous to young children's developing vision. In an official statement from Nintendo of America, spokesman Charles Scibetta said, "Nintendo's position is children 6 and under should not use the 3-D feature of Nintendo 3DS, and parents should use the parental controls feature to restrict access to the 3-D mode."

The video game device is set to be released by March, and will sport a 3.53-inch LCD display that enables 3-D vision without the need for special glasses, according to Nintendo. The device also includes a 3-D depth slider that players can use to adjust the level of the 3-D effect.

Dr. David Hunter, chief of ophthalmology at Children's Hospital Boston and a professor at Harvard Medical School, said Nintendo was just being "overly cautious, since the science behind the concern is that the child's developing visual system is sensitive at that age."

A child who plays the 3DS is unlikely to suffer any permanent problems caused by playing with the toy, Hunter told MyHealthNewsDaily. But kids' vision is more easily impacted when they're younger they can develop problems including their vision becoming blurry in one eye, or they can become cross-eyed so Nintendo likely did not want to take any chances that the company could be held liable for such problems if they arise, he said.

Games are worse than television

3-D entertainment called "stereo" 3-D, to differentiate it from our real, 3-D world has infiltrated television and movies, and now gaming systems, Banks said. The technology works by off-setting two slightly different images to create a three-dimensional effect.

But the off-setting of the images creates a conflict between the way our eyes focus and how our brain processes distance, he said. This can lead to eye fatigue and discomfort, according to a 2008 study Banks published in the Journal of Vision.

Headache, eye strain and fatigue are other possible side effects of watching 3-D images, Banks said.

A person's distance from the screen and how much the content appears to pop off the screen can also make a difference in causing eye strain and fatigue, according to Banks' study.

"If the content stays near the screen, meaning you're not popping characters way in front or behind the screen, then we found people don't have bad symptoms," Banks said. "So from that, we'd say video games are more of a concern than television, and television is more a concern than cinema" because video game screens are closer to people's faces than a 3-D movie in a theater.

Still, no research has established a limit on the amount of time a child should spend watching stereo 3-D images, Banks said.

So what should parents do?

Anything a child sees at a young age is incorporated into the connections that form in the brain until age 8, said Dr. Lisa Park, clinical assistant professor of ophthalmology at New York University Langone Medical Center.

"When you look around to see, then you have to see clear, good images for those connections in the brain to be made appropriately," Park told MyHealthNewsDaily.

But research hasn't shown that parents need to start worrying about their kids playing 3-D games or watching 3-D movies and TV shows, she said.

Parents should, however, make sure their children's eyes are screened by an ophthalmologist to make sure they don't have any underlying vision problems, Park said.

After that, parents just need to use their best judgment for allowing kids to play with the 3-D video games, she said.

"Any child shouldn't be playing video games for 10 hours, and that's unquestionable for younger ages," Park said. "Use good judgment in limiting video-game time, there's no hard and fast rule for hours or minutes."

Nintendo has issued recommendations for all its video game devices to reduce the risk of eyestrain. For example, the company advises players of the Nintendo Wii and the Nintendo DS to take a 10- to 15-minute break for every hour of play.

Pass it on: Despite Nintendo's warning that kids 6 and younger shouldn't use the 3-D feature on its upcoming 3DS video game system, eye doctors say there are no serious vision-related health effects associated with 3-D play.

Follow MyHealthNewsDaily staff writer Amanda Chan on Twitter @AmandaLChan.