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Achieving Stereopsis (Depth Perception) and 3D Vision – It's Not Just For Kids.

For years, it was thought that once a patient was past the age of 8, the opportunity to correct binocular vision disorders – such as stereodeficiency - was lost. The good news is studies have shown this to be false. 

We often receive calls from adults about lack of depth perception (stereopsis). In a natural, real life setting the retina in each eye forms a two-dimensional image of our surroundings. Each eye produces a slightly different image because the eyes are in different locations. Our brain processes these two images and combines them into one 3D visual experience. 

3D is our ability to:

• Judge distances
• To be aware of our position in space
• Experience depth-perception

Gordy Slack explains it well in an article for the Berkeley School of Optometry:

“Most people who have full depth perception take it for granted. They develop the ability as infants and it quickly becomes one of the fundamental characteristics of their world. But for at least ten percent of North Americans, vision abnormalities preclude stereopsis. Usually, the problem arises because one eye is stronger than the other (amblyopia) or because the eyes are misaligned (strabismus). In both cases, the two images sent to the brain’s visual cortex, where they usually are interpreted and formed into coherent mental pictures, cannot be fused into one, deep, holistic image. To avoid the tangle of conflicting signals, the brain often opts either to ignore most information coming from one eye (which then further weakens) or to alternate back and forth between the eyes. Both strategies avoid the confusion of equivocal inputs, but neither is compatible with strong stereo vision.”

Individuals who have vision conditions such as amblyopia (an imbalance in visual strength between the two eyes), strabismus (misaligned eyes), or other conditions that inhibit focusing and depth perception will have difficulty seeing 3D. It is estimated that as many as 3 to 9 million people in the United States have vision problems that inhibit their ability to properly see 3D. And as many as 56% of people between 18 and 38 years of age suffer from symptoms related to depth-perception problems.

In order to have proper depth-perception and perceive 3D an individual must have:

• Accommodation – lenses in the eyes must change shape and maintain clear focus as objects move
• Aerial perspective – the ability to perceive contrast differences between nearby objects versus distant objects
• Parallax – perceive differences as the head moves from side to side, closer objects appear to move more than distant objects
• Size familiarity – the ability to tell how far away an object is based on how large or how small it looks
• Stereoscopic (binocular) vision – the two eyes provide slightly separate images to produce the perception of depth and 3 dimensional structure

Treatment and Treatment Goals

When seeking treatment it is important to discuss goals. 

For some individuals treatment is considered more rehabilitative – returning to normal function. For others, such as athletes, it is considered vision enhancement – taking their vision to superior performance.

For many adults with stereodeficiency, there is hope.

From a study by Jian Ding and Dennis M. Levi in PNAS:

“Stereoblind or stereodeficient individuals who recover stereopsis may gain substantial benefit in everyday life. After achieving stereopsis, our observers reported that depth “popped out” in daily life. They feel more confident in daily tasks that are related to depth perception and are able, for the first time, to enjoy 3D movies.”

Diagnosis and treatment of binocular vision disorders is a specialty in and of itself - requiring advanced training and clinical experience. When discussing treatment it is important to evaluate candidacy for vision therapy, potential surgical outcomes, and the possibility of combined treatment to include both vision therapy and surgery. The goal with any treatment is to maximize potential outcomes and achieve individual treatment goals.

If you, or someone you know, is living with stereodeficiency – give us a call. We have been treating binocular vision disorders since 1991 – and are considered the Northwest's premiere vision therapy clinic.