Seeing triple at the 3-D movie? Films can cause dizziness, nausea

Thousands of people are packing movie theaters across the country to see the new "Alice in Wonderland" in 3-D, and dozens of them will likely leave with headaches.

That's not a criticism of the film, but a fact: Doctors say those with less-than-perfect eyesight can suffer nausea, blurred vision and dizziness from 3-D movies.

"The 3-D technology taps into our depth perception," said Dr. Lawrence Tychsen, ophthalmologist in chief at St. Louis Children's Hospital. "To fully appreciate depth in a 3-D movie, you need equally clear vision in both eyes. Even a small misalignment could contribute to those symptoms of discomfort."

Tychsen said relatively minor conditions such as nearsightedness, farsightedness or a lazy eye — if not treated with glasses or contacts — could trigger headaches and other side effects from 3-D visuals. He estimated that up to 20 percent of the population — kids and adults — could be affected.

"Many people are unaware that anything's wrong until they experience a 3-D movie and have these symptoms," Tychsen said.

The problem comes from so-called vision fatigue, caused when 3-D technology forces the eyes to make constant adjustments to focus on images that are simultaneously near and far away. Humans see in three dimensions, but the exaggerated imagery of 3-D movies can cause a strain in some, according to Jeffrey Anshel, a California optometrist who has researched vision fatigue in computer users.

"Each person will experience it differently," Anshel said, adding that vision fatigue tends to be more pronounced during longer 3-D movies. "I think that a two-hour movie is fine, but going into three or more hours could lead to eye strain."

Reports of vision fatigue popped up in recent months after the release of the 3-D blockbuster "Avatar," which has shattered box office records, raking in more than $2.5 billion worldwide and becoming the highest-grossing film of all time. Several theatergoers complained of motion sickness after watching James Cameron's epic sci-fi adventure, filmed with breakthrough digital 3-D techniques.

Despite causing discomfort in a small number of people, 3-D movies aren't going away anytime soon. Besides "Avatar," some of last year's other top-grossing films — "Up," "Ice Age: Dawn of the Dinosaurs" and "Monsters vs. Aliens" — were 3-D, and more than a dozen other 3-D movies are scheduled for release this year and next.