Depth perception is a pretty amazing thing. It allows us to see the world in three dimensions; for us to crawl, navigate stairs, play catch with a ball, drive and many more activities. But what happens if our depth perception is impaired? These activities become exponentially more difficult, and may be even impossible. Read more about visual problems here.
What is Depth Perception?
Depth perception is a visual processing skill that allows us to perceive visual input in multiple dimensions. The American Academy of Ophthalmology describes depth perception as the ability to see things in three dimensions (including length, width and depth), and to judge how far away an object is. Read here for more information to understand this visual skill.
When Does Depth Perception Develop?
We are not born with the ability to perceive depth. In the beginning, we are only able to see two dimensions, making everything appear flat, for the first 6 months of life. During this time, our eyes are not yet working together and monocular vision is predominant.
Around 6 months of age, our eyes begin to work together, and binocular vision, the use of the eyes together, becomes a dominant pattern. Binocular vision patterns is what allows our brains to perceive depth and view the world in a three dimensional way. This is because both sides of the brain are receiving input, and interpreting that information in synchrony.
However, our depth perception must grow and develop over time as new challenges are presented.
As we move through gross motor development from rolling, to sitting, crawling and walking, our depth perception and binocular vision is constantly challenged to meet our gross motor needs.
As the left and right sides of the brain begin to strengthen communication through the reciprocal motor patterns of crawling and walking, our binocular vision, neck strength and neck control is also then indirectly developed.
Impact of Impaired Depth Perception
Impaired depth perception can leave a child with significant challenges in life. Individuals with impaired depth perception may struggle with sports, navigating familiar and unfamiliar spaces, and may even struggle with driving. These are just a few areas that may be impacted, but in reality, all areas of a person’s life are affected by impaired depth perception.
Signs of Impaired Depth Perception
The signs of impaired depth perception are often very subtle and may be missed at a young age or passed off as “slow” to develop, with serious concerns being caught at an older age.
Signs of impaired depth perception include:
Late to crawl or walk
Hesitancy or fear of surface changes
Resistance to going up and down stairs
Exaggerated stepping over lines in the floor or parking lot
Inability to catch/hit a ball—early anticipation or late response
Runs into furniture, walls or items in a familiar environment that have not changed position
Difficulty anticipating turns or space needed to navigate playground equipment and use ride on toys
Overshoot or undershoot when reaching for an item
Heavy footsteps or stomping up down stairs and over items/changes in floor surface
Frequent falling up or down stairs
How is Depth Perception Assessed?
Due to the complexity of monocular and binocular vision, your therapist may recommend an evaluation with a developmental optometrist if they note any of the signs of depth perception impairment above. Chances are that your therapist has also noted other vision concerns during a vision screening that has lead them to suspect poor or impaired depth perception.
Depth Perception Treatment
Depth perception impairments are treated in vision therapy as directed by a developmental optometrist or an occupational therapist with special training in vision therapy. Treatments provided by either professional utilize special equipment, lenses and activities that challenge binocular vision directly.
Final Note on Depth Perception
Poor or impaired depth perception can be identified and addressed at any time throughout childhood. Like many vision impairments, there are a wide variety of presentations and levels of severity in which your child may present with. If left unaddressed, your child may continue to struggle with self care, sports, driving, and many other tasks later in life. If you have concerns, ask your OT for a vision screening and to discuss your concerns.
What if you suspect vision problems?
Now what? When vision problems are suspected after a screening by the OT, it is best practice to refer the family to a developmental optometrist.
A developmental optometrist will complete a full evaluation and determine the need for corrective lenses, vision therapy or a home program to address vision concerns.
As occupational therapists, it is imperative that we rule out vision problems before treating handwriting or delays in visual motor integration, to ensure the best possible trajectory of development and success for the child.