Why 3D movies make you sick, new study unfold the truth

3 D effect-- A still from James Cameron's film "Avatar" 

Oregon (USA): "Avatar," "Hugo" and other 3-D movies thrill many viewers, but also make some feel sick, a new study finds.

3D film can disorientate the brain, causing eye strain, headaches, nausea and sickness, study shows.

A study conducted by Pacific University faculty and published in the current edition of Optometry and Vision Science identifies causes of visual and physical discomfort in some people when they watch stereoscopic (3D) video content. 

In one experiment researchers at Pacific University asked 203 teenagers and adults to watch the 2009 family film Cloudy With a Chance Of Meatballs on a 55-inch LCD television. Some watched it in regular 2D; others viewed it in 3D.

Viewers were seated at different distances and viewing angles, and questioned about previous viewing symptoms, and any symptoms during or after seeing the film.

Twelve per cent of the 2D viewers reported an increase in symptoms of discomfort, compared with 20 per cent of the 3D viewers. Those who watched the 3D version were likely to report more eye pain, pulling sensation in the eye, blurred vision, double vision, dizziness and disorientation.

Viewers aged 24 to 34 were bothered more by the 3D images than older viewers, the researchers found.

“3D movies are only good as long as you’re not feeling terrible,” said study lead author Shun-Nan Yang, a senior scientist at Pacific University College of Optometry in Forest Grove, Oregon.

The most severe problems reported were headaches and nausea, Yang said. Symptoms could increase within 15 minutes after watching the film, he said, although the problems didn’t last into the next day.

The study also found that younger viewers incurred both higher immersion and greater visual and motion sickness symptoms while viewing 3D video, "especially when viewing from a closer distance or more direct angle."

Watching movies in 3D is visually challenging because the eyes must adjust to the fixed closeness of the screen and the seeming distance of the 3D images, he said. If you’re in a movie theatre, he said, you may experience fewer symptoms while watching 3D than viewing the film at home.

Older viewers were less sickened by 3D than younger viewers, possibly because they’re less sensitive to visual stimulation or the deterioration of their eyes makes it easier to handle the near/far discrepancy, he said. Younger viewers reported more “immersion” in the 3D movie.

Yang said it’s a mystery why many viewers have visual or physical complaints after watching ordinary movie images on TV. Those people also said they suffered eye problems when they used computer monitors, he said.

If you’re watching a 3D movie at home, Yang said, you might avoid symptoms.  

The study becomes important in the sense when prominent film makers are emphasizing to make release their films in 3 D and become significant in the current era when recently released Avatar proofed to be blockbuster.   

The study appears in the July issue of Optometry and Vision Science.