Most people crowding into cinemas for the latest Hollywood 3D blockbuster are impressed by the spectacle but there are some who don’t get the hype, and miss the special effects, because of binocular vision problems.
The inability of some people to see the illusion of 3D – used with such great effect in movies such as Toy Story 3, Avatar and Alice in Wonderland – sometimes unmasks an unrecognised vision problem they may have had for some time.
“Quite simply, people who have even a small vision misalignment or those who don’t have equal vision in both eyes may not be able to see 3D images properly,” says Dr. Leonard Press, of the American Optometric Association (AOA).
“Individuals with unstable focussing or difficulty in coordinating vision with other senses can experience headaches and other uncomfortable side effects from viewing 3D movies.”
The inability of some people to see the illusion of 3D – used with such great effect in movies such as Toy Story 3, Avatar and Alice in Wonderland – sometimes unmasks an unrecognised vision problem they may have had for some time
It is sometimes referred to by medical professionals as an ‘avatar headache’. Children playing 3D games for long hours may also be susceptible to the problem.
The AOA estimates as many as 56 per cent of people between 18 and 38 years of age suffer from symptoms related to depth-perception problems.
It recommends that anyone who experiences complications after watching 3D movies or TV be checked for vision misalignment. The most common complaints are headaches, blurred vision and dizziness.
These problems have to do with binocular vision, the ability to align both eyes on a target and combine the visual images from the two eyes into a single, three-dimensional perception. Three dimensional technology creates fatigue by forcing to eyes to make adjustments to focus simultaneously on images that are near and far away.
“We have 3D because we have two eyes in our head in slightly different places,” Dr. Dominick Maino, a professor at the Illinois College of Optometry and the Illinois Eye Institute, explained.
“When the brain puts two images together, that’s when we get the 3D effect. 3D is really our ability to judge distances,” he says.
Three dimensional movies recreate this effect by feeding different images into each eye using polarised lenses that pick up separate images or by timing the images between the two eyes.
The AOA says several different vision disorders could be the cause of difficulty viewing 3D movies, including:
- Amblyopia, or lazy eye, which occurs when one eye does not see as well as the other
- Strabismus, or crossed eyes, in which the eyes do not line up in the same direction when focussing. Ultimately, a person with strabismus begins to suffer from double vision or loses the ability to see in 3D
- Convergence insufficiency, in which the eyes are incapable of turning toward each other to fix on the same distance.
However, Dr. Maino says studies also show optometric vision therapy can help alleviate these problems. Optometric vision therapy re-educates the brain to achieve single, clear, comfortable, two-eyed vision that improves eye coordination, focussing and eye movement.