Depth perception requires a rather complex process involving separate images seen by each eye and how the brain interprets those images. Loss of depth perception can cause accidents and anxiety.
Poor depth perception in children can be a sign of more serious vision problems that need to be addressed right away to prevent permanent vision loss and learning disabilities. Declining depth perception in adults can be a sign of progressive eye conditions.
How We Perceive Depth in Stereovision
To get a 3-D picture of your environment, both eyes must be working properly and working together. Your brain takes both images and combines them into one image, which is what you see.
If one eye is producing a better quality image than the other, your brain will normally pick the best image and block out the poor one. You may not even be aware that you are only really seeing the image from one eye.
Your eyes must work together properly. They have to point at the same spot and move simultaneously. When they are working together they give the brain two images that can be combined into what appears to you as one fluid image. If they are not working together properly, your brain will block out one image, or you will experience double vision.
You can also perceive depth with just one image, based on monocular cues. Artists use monocular cues to create the illusion of three dimensions in flat paintings and drawings. Monocular cues include:
- Shadows and highlights
- Overlapping objects
- Linear perspective – objects appear smaller the farther away they are
- Color and contrast – more vivid colors appear to be closer, as do sharper edges and outlines, in the distance colors fade and outlines blur
- Motion parallax – as you move, very close objects move completely across your field of vision while very distant objects will appear to stand still or move very slowly
Causes of Poor Depth Perception
Poor depth perception can be the result of lack of stereovision or difficulty with monocular cues. Causes can include:
- Cranial nerve palsy
- Anisometropia – different refractive power in each eye
- Cataract affecting one eye
- Cataracts or macular degeneration causing loss of color vision or contrast
Solutions for Poor Depth Perception
In many patients, correcting depth perception problems is as simple as correcting a refractive error so that both eyes have the same visual acuity. This can be done with corrective lenses, but it still leaves you at risk for falls and other accidents when you are not wearing your lenses causing your depth perception to fail. Vision correction surgery can restore your depth perception while correcting your vision.
If you have problems with your depth perception or if you would like more information about laser vision correction, please contact Dr. James Kelly today at Kelly Laser Center, with state-of-the-art vision centers in Long Island, Manhattan, and NYC.