Stereopsis

Stereopsis is the perception of depth and 3-dimensional structure obtained on the basis of visual information deriving from two eyes by individuals with normally developed binocular vision. Because the eyes of humans, and many animals, are located at different lateral positions on the head, binocular vision results in two slightly different images projected to the retinas of the eyes. The differences are mainly in the relative horizontal position of objects in the two images. These positional differences are referred to as horizontal disparities or, more generally, binocular disparities. Disparities are processed in the visual cortex of the brain to yield depth perception. While binocular disparities are naturally present when viewing a real 3-dimensional scene with two eyes, they can also be simulated by artificially presenting two different images separately to each eye using a method called stereoscopy. The perception of depth from such images is known as stereoscopic depth.

Mechanism of Stereopsis

The brain combines the inputs from each eye to give rise to a perception of depth, or three dimensions. This is possible because the brain has access to information about the degree of convergence of the eyes (how much they are turned inwards), and can use this information to estimate the distance to objects that are fixated.

Clinical Significance

Stereopsis is very sensitive to disruption and is often absent in individuals with strabismus and amblyopia. Stereopsis may also be affected by age-related macular degeneration and other types of vision loss.

See Also

• Binocular vision
• Depth perception
• Stereoscopy
• Strabismus
• Amblyopia
• Age-related macular degeneration

References

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  Charles Wheatstone's mirror stereoscope from the 19th century
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  Diagram of how to view a stereogram
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  View of stereogram for the left eye
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  View of stereogram for the right eye
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  Composite view of the stereogram
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  Depth map of the stereogram