Depth Perception

What is depth perception?

Depth perception (also called stereopsis) is the ability to perceive the world in three dimensions. Depth perception allows for accurate estimations of distance and an accurate spatial map of our environment.

How do we see in 3d?

Because of the spacing of the eyes, each eye collects a slightly different picture of the surroundings. The brain then puts these two pictures together in a process called “fusion” where one image is made. The differences in the pictures allow for three-dimensional vision.

Depth perception should be well developed by the age of 2. Since depth perception demands binocular vision, getting an eye exam as recommended will ensure that normal development is not delayed. Conditions like strabismus (eye turn), or anisometropia (a different refractive error in each eye greater than one diopter), or other problems can cause an eye to be suppressed causing a condition called amblyopia where there is poor binocular vision and therefore poor depth perception. Only an ophthalmologist or optometrist would find these problems.

Assessing depth perception

A simple tool called the Randot Stereo Test may be used in the optometry office as a quick measure of depth perception. A test involving lining up two sticks at a distance called the Howard-Dolman test is also a way to assess depth perception. Assessing depth assessment could be helpful as reduced stereopsis was found to be common in older patients with falls (1) along with reduced acuity. Again, the necessity for eye exams cannot be overstated for all populations.

Monocular Depth Perception

What if there is only vision in one eye? The brain will learn monocular cues for depth that will allow for the person to safely function, drive and even play sports. Brains are amazing!!

(1)Källstrand-Eriksson, J., Hildingh, C., & Bengtsson, B. (2016, July 11). History of falling and visual ability among independently living elderly in Sweden. Retrieved from

7 thoughts on “Depth Perception”

  1. Is there a screen you use for depth perception? And if you suspect a deficit in this area can you refer to a regular optometrist (for adults) for diagnosis? Or is a neuro optometrist needed?

  2. Hi there,
    I have taken the Vision 101 for OTs in the school and recently received an evaluation for a student diagnosed with stereo blindness. I was wondering if there are any specific tests I should use to help determine his current functioning on a standardized level. I did the BOT-2, MVPT-4, and the Sensory Processing Measure. (He does have some sensory differences and some “behaviors” that I imagine are due to working hard on all his visual tasks.) He actually scored in the average range across the four subtests I did for BOT-2 (fine motor precision, fine motor integration, manual dexterity, and bilateral coordination) and on the MVPT-4. I have the DEM available, would this be a good one as well?
    Thank you!

    1. You can do the DEM to make sure saccades are not affecting reading. This condition may have minimal functional impact though it is worth checking out like you are doing.

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