Submitted by Denise Reynolds RD on 2010-07-14
The technology for 3D movies has come a long way since the first American color feature Bwana Devil in 1952. However, one issue hasn’t changed over the years – eye-related health issues can be a problem for some viewers.
Stephen Glasser, a Washington optometrist, says that more people may discover eye problems as 3D movies become more mainstream. According to the National Association of Theatre Owners, almost 10% of US movie screens are now capable of projecting in 3D, up from 1.5% in 2007. There are approximately 20 3D movies set to release in 2010.
Television is also going 3D. ESPN has launched a 3D channel, which broadcast 18 of the World Cup soccer matches, and Discovery plans their own channel in early 2011.
To generate a three-dimensional effect, a special projector displays two identical images on the screen, but from slightly different angles making one appear close and the other to appear far away. Special polarized glasses are worn that force one of the images to enter the left eye and the other to enter the right. The two images travel to the visual cortex, the area of the brain primarily responsible for processing vision. This creates the illusion of three dimensions.
Early 3D movies used color to set the images apart, and viewers wore paper glasses with one lens colored red and the other colored blue. These tended to give viewers headaches, eyestrain, and nausea.
Today’s 3D with digital technology gives crisper, clearer images and fewer problems, however there is still a risk of visual fatigue and “simulator sickness”, a type of nausea that also plagues users of flight simulators, head-mounted virtual reality displays and other 3D applications.
In Italy, the ministry of health has other concerns about 3D movies – specifically the cleanliness of the borrowed glasses. They confiscated 7000 pairs of 3D glasses from cinemas, stating that they were not properly disinfected between screenings and lacked tags that proved that they do not cause vision problems. When seeing a 3D movie here in the States, it is best to carry an antibacterial spray or wipe – just in case.
3D can have some advantages – some patients actually discover health problems because they are unable to see the images clearly. About 2 to 3 percent of people have an eye condition where only one of the eyes turns inward to track a close object. The condition is called vergence accommodation conflict. Other conditions that cause 3D movies to fall flat include lazy eye (amblyopia), strabismus, keratoconus, or poor vision in one eye due to cataracts, glaucoma or retinal problems.
Treatments for eye conditions that cause 3D vision viewing include surgery for cataracts or glasses/contacts to correct poor vision in one eye. There is also vision therapy for those with convergence insufficiency, where the patient spends an hour once a week doing eye-strengthening exercises