Binocular Vision & Depth Perception

The eyes are designed to focus images clearly on the retina and then to relay that image to the brain. If both eyes are lined up on the same target, the visual portion of the brain can fuse the two pictures into a single 3-dimensional image. This creates binocular vision and depth perception, which helps the eyes work together to transmit one “picture” to the brain.

When one eye turns as in strabismus, two different pictures are sent to the brain. In the young child, the brain learns to ignore the image of the misaligned eye and see only the image from the straight or better-seeing eye. The image of the worse eye is suppressed. This causes loss of depth perception. Adults who develop strabismus usually have double vision because their brain is already trained to receive images from both eyes and cannot ignore the image from the weaker or turned eye.