3-D Movie Effects Can be Affected by Vision Problems

< Sep. 22, 2010 > -- Improved 3-D film-making technology has people packing into theaters to enjoy the latest releases of 3-D blockbuster movies. However, not everyone is able to enjoy the special 3-D effects.

"There will be at least one person in the crowd who says, 'What are you talking about? I didn't see anything flying out at me.' Or maybe they will say, 'That movie actually made me a little nauseated,'" says Dr. Dominick Maino, a professor at the Illinois College of Optometry and the Illinois Eye Institute.

Vision Problems Can Negate 3-D Effects

From 3 million to 9 million people in the United States have vision problems that keep them from enjoying such 3-D movies as Avatar and Toy Story 3, estimates the American Optometric Association. And as many as 56 percent of people between 18 and 38 years of age suffer from symptoms related to depth-perception problems.

These problems have to do with binocular vision, which is the ability to align both eyes on a target and combine the visual images from the two eyes into a single, three-dimensional perception.

Dr. Maino explains, "We have 3-D because we have two eyes in our head in slightly different places. When the brain puts two images together, that's when we get the 3-D effect."

"3-D is really our ability to judge distances," he says. "It's a real nice survival trait, so we could tell how far away that saber-toothed tiger is and have him for lunch rather than the other way around."

How Technology Creates 3-D Effects

Movies done in 3-D recreate the effect by feeding different images into each eye, Dr. Maino says. In the early days, 3-D glasses would have one red lens and one blue lens, and there would be one red image and one blue image on the screen separated by a little distance. One eye would be able to see only the red and the other only the blue, and the brain would fit them together to form an in-depth perception.

Today's technology today is more advanced. The 3-D effect is currently created using polarized lenses that pick up separate images or by timing the images between the two eyes. "One image will be placed on one eye and then very quickly the other image is placed in the other eye," Dr. Maino says. "When the brain puts that together, it gives the sense of 3-D."

However, people who are having problems with their binocular vision will either not be able to perceive the illusion of 3-D, or they will find that the movies or TV shows actually give them "visual hangover," according to Dr. Leonard Press, a spokesman for the American Optometric Association and optometric director of the Vision and Learning Center in Fair Lawn, N.J.

An association poll found that headaches, blurred vision and dizziness are the most common side effects from 3-D movies for people who have binocular vision difficulties. "After the movie, they're a bit dizzy, and it takes them a while to get back to normal," Dr. Press says.

Various Vision Problems May be Involved

Dr. Maino says several different vision disorders could be the cause of the problem, including:

• Amblyopia, or lazy eye, which occurs when one eye does not see as well as the other. Because of that difference between the two eyes, the ability to see 3-D is greatly reduced or absent.
• Strabismus, or crossed eyes, in which the eyes do not line up in the same direction when focusing. Ultimately, a person with strabismus begins to suffer from double vision or loses the ability to see in 3-D.
• Convergence insufficiency, in which the eyes are incapable of turning toward each other to fix on the same distance.

Any of these conditions can be treated by an optometrist or ophthalmologist. In fact, Dr. Maino says, the new 3-D movies are giving some people their first clue of a vision problem they may have had for a long time without recognizing it.

These problems can be treated using optometric vision therapy, in which eye patches or special pairs of glasses are utilized to teach the eyes how to work together, Drs. Press and Maino say. Some of the techniques already are used to help kids with amblyopia or strabismus.

"It's a form of physical therapy for the eyes," Dr. Press says. "The key is helping your eyes work together with your brain. You do different activities that help both eyes work together. It's almost like lifting weights."

By the end of vision therapy, "we should have someone who has single, clear, two-eyed vision," Dr. Maino adds.

Always consult your eye care provider for more information.

Don't Take Your Eyes for Granted

Imagine what life would be like if you could not see well. Reading might be out. Watching a movie could be tough. Focusing on the face of a loved one could drive you to tears.

The number of people losing their vision is growing, yet experts say much of this vision loss could be prevented.

"We can intervene best when we identify a problem in the early stages," says Dr. Roy S. Rubinfeld, a clinical correspondent for the American Academy of Ophthalmology (AAO). He warns against putting off regular eye exams because your eyes feel fine or you don't wear glasses or contact lenses. Signs of some eye diseases, such as glaucoma and age-related macular degeneration (AMD), are present before you might notice symptoms.

The National Eye Institute says more than 3.3 million Americans ages 40 and older have blindness or low vision. The institute projects that figure will increase markedly by the year 2020. The percentage of people more than 60 years old who suffer vision loss is growing fast, too.

"At 60, everyone should have an annual eye exam, even if you're seeing very well," Dr. Rubinfeld says.

Many diseases cause vision loss as we age, but AMD is the Western world's top cause of blindness. Leading to loss of your central vision, it may cause dark spots in your sight, make straight lines appear wavy, or cause text to seem blurry. AMD, glaucoma, diabetic retinopathy, cataracts, and dry eye syndrome can all rob you of sight.

It is best to see your eye doctor before trouble starts. But these signs should prompt a visit at once:

• trouble seeing objects close up or far away
• colors that seem faded
• poor night vision
• double or multiple vision
• loss of side vision
• poor central vision or straight objects that look wavy
• blurry text or type

Dr. Rubinfeld offers these recommendations to help preserve your vision:

• See your eye doctor regularly (each year if you're 60 or older).
• Do not smoke.
• Use sunglasses that block ultraviolet (UV) rays in bright sun or at high altitudes.
• Exercise regularly.
• Eat healthy.

Always consult your eye care professional or other healthcare provider for more information.