How Does 3D Vision Work?
A guest article by Orlin Sorensen of Rebuild Your Vision
With the release of Avatar and other action-packed 3D movies this year, it's clear that 3D vision is back in Hollywood and hotter than ever. But why do you need those goofy oversized glasses to watch movies in 3D? And how does 3D work?
 How Does 3D Vision Work?
Unlike the eyes of the space aliens featured in some 3D features, our eyes are not positioned together, but lie approximately 3 inches apart. This separation causes each eye to see the world slightly differently. The brain fuses these two views together and uses them to calculate distance, creating our sense of depth.
3D glasses work similarly, feeding different images into your eyes (thus the two different-colored lenses: one red, one blue). In a theater, the movie screen actually displays two images, and the glasses cause one of the images to enter one eye and the second image to enter the other.
It may surprise you to learn that the ability to visually perceive three-dimensional space - called "binocular depth perception" - can be achieved without external aid. In fact, this ability is a way to measure parts of our vision: if you can successfully combine separate images from two eyes into one three-dimensional image in your brain, your binocular vision is working well. Both eyes are working as a team.
Yet not all people have binocular depth perception. According to the Optometrists Network, up to 12% of the population has some type of binocular vision disability:
the two most commonly known types are amblyopia and strabismus.
Amblyopia and Strabismus (Lazy Eye and Walleye)
Amblyopia, from the Greek word amblys meaning blunt or dull, is a condition in which one eye has lowered visual acuity and/or poor muscle control. Your eyes may be straight, but one eye doesn't send the proper information to the brain, so your brain can't perceive binocular depth. Amblyopia - also known as "lazy eye" - affects approximately 2 or 3 out of every 100 children in the United States.
Conversely, strabismus, from the Greek word for squint, is a visual defect in which you may see clearly, but your eyes don't line up - the two eyes point in different directions. One eye may turn in, out, up, or down, while the other eye looks straight ahead. That's why strabismus is more commonly known as "walleye" or "wandering eye." Strabismus affects 4 out of 100 children in the United States.
These conditions are not always easy to diagnose. With strabismus, particularly, the eye misalignments may not obvious to the untrained observer. And it used to be that doctors thought lazy eye could only be treated in childhood, up to about 8 years old. Currently, treatment is given at any age.
So next time you're watching a movie in 3D vision, give your eyes a screening, too. You can test your binocular depth perception by first covering and then uncovering one eye: if the image floats out from the screen, your eyes are working in tandem. If the image remains flat, you may have a vision problem, so consult your ophthalmologist. And if you see any space monsters coming for you... duck!
 About The Author
Orlin Sorensen is the creator of Rebuild Your Vision, an eye exercise course designed to help anyone improve their natural vision. With vision training routines designed for high degrees of myopia, hyperopia, presbyopia and astigmatism, Rebuild Your Vision can help you overcome your need for glasses and contact lenses for life.
|
