Nintendo Co.’s new 3DS hand-held game system will carry an ominous-sounding warning for young children about the possible side effects of looking at three-dimensional images.
The machine, which goes on sale Saturday in Japan, raises safety concerns about the technology, just as it is expected to spread 3-D content to millions of users,
Scientists and ophthalmologists say that, for most of the population, looking at 3-D images in moderation poses no greater risks than those associated with 2-D content. But some eye doctors are looking into whether the technology may affect a small minority of children with a pre-existing eye condition. Scientists are also working on international 3-D guidelines to prevent faulty devices or poorly made content from causing discomfort.
As 3-D technology becomes more widely available with the spate of new movies from Hollywood and a push by the electronics industry to bring 3-D products into the living room, the questions surrounding possible safety risks have heightened.
Nintendo’s warning for 3DS users is two-fold. First, it says that some experts think prolonged exposure to 3-D images may hamper the eye development of children six years old and younger.
Second, it says both adults and kids may experience more eye strain when playing videogames in 3-D mode, compared with conventional 2-D games.
Samsung Electronics Co., Sony Corp. and other electronics companies have issued similar warnings on their 3-D products.
The warnings by Nintendo and others reflect a cautious tone toward the technology because there is no medical evidence to support the idea that 3-D content might hinder children’s eye development. The side-effects may depend on factors not directly controlled by manufacturers, including how the content is produced and the amount of time spent watching 3-D images.”There are no reasons to feel scared about 3-D,” said Hiroyasu Ujike, a visual scientist at Japan’s National Institute of Advanced Industrial Science and Technology.
All 3-D displays deliver separate images to right and left eyes of the viewer, and the brain then creates the illusion of depth by stitching together the two images. Currently, the most common method is to use special glasses that open and shut one lens at a time.
The Nintendo 3DS, which goes on sale Saturday in Japan and next month in the U.S. and Europe, does this without glasses by placing a material in front of the display with precisely placed slits that show each eye a different set of the screen’s pixels. The 3DS also offers the option of playing games in 2-D. As far as possible safety risks, scientists said there is no difference between the two methods.
However, some ophthalmologists in Japan are studying whether prolonged 3-D viewing might affect children who have a condition called esophoria, a tendency of the eyes to deviate inward.
Takashi Fujikado, a visual-science professor at Osaka University’s Graduate School of Medicine, is starting research on whether children afflicted with esophoria, who are constantly making extra effort to prevent their eyes from becoming cross-eyed, may find it difficult to return the eyes to normal position after watching 3-D images for a long period of time.
When a 3-D image pops out from a screen, it draws the eyes inward to focus on an object that appears closer. This may affect children six years old and younger because their eyes, still under development, are more sensitive to such stimuli, he said.
Children with such a condition are rare but it is difficult to determine how many there are, Mr. Fujikado said, because esophoria doesn’t necessarily have symptoms.
The second part of Nintendo’s warning covers a large audience including older children and adults, and it echoes some common complaints about 3-D. Viewing 3-D images may cause eye strain and other signs of discomfort such as dizziness, nausea and headaches. Scientists have discovered that these negative side effects may vary based on how the 3-D is produced by content makers and how it is presented by electronics makers.
Martin Banks, a professor of vision science and optometry at the University of California, Berkley, said his research has found that people suffer eye strain when a virtual image jumps out or fades back too far from the display screen their eyes are fixed on. He co-authored an article in the July 2008 issue of “Information Display” journal titled “Consequences of Incorrect Focus Cues in Stereo Displays.”
“The only thing that you can do at that point is to have the creators of the content to pay attention and not have the content way in front of the screen or way behind the screen,” said Mr. Banks, who has done research on 3-D since 1995.
Mr Ujike also heads an working group at the International Organization for Standardization, or ISO, that aims to establish international safety guidelines for risks associated with 3-D images by around 2014. The guidelines will not be binding, but will serve as reference material to help ensure 3-D safety.
Most companies making 3-D TVs and game machines are setting internal safety standards after consulting experts. Nintendo has provided game developers with instructions to ensure the 3-D game content they create for the 3DS meets safety standards.