Depth perception is the ability to see in three dimensions: length, width, and depth and to judge how far away the object is located. Depth perception is only possible when we have good binocular vision which means the effective use of both eyes to view the world.
Our eyes view an object from slightly different angles and our brain compares and processes the two sets of information to form a single image. When both eyes see clearly and the brain can process a single image effectively, it is called stereopsis. Stereopsis is not present at birth but develops at 3-6 months of age.
An eye doctor may use one of many tests to check your depth perception. The most common test is called a vectograph and uses polarized 3D glasses. You may be asked to point out which animals, circles or forms are coming out of the page towards you.
Why is depth perception important?
Depth perception allows you to have the best view of the world. It makes numerous activities easier to perform and helps us to move through life without collisions. It improves your safety by knowing how close or far away objects are. Depth perception makes it easier to parallel park, back your car out of a parking spot, and run up and down stairs, and is key to being a great athlete.
Many sports including baseball, gymnastics, volleyball, and tennis require good depth perception.
Why would you have poor depth perception?
Your depth perception may be poor for a few reasons. If you are not using both eyes together in the same way or the vision is unequal between your two eyes, depth perception will be difficult. Amblyopia, strabismus, presbyopia, unequal refractive error, or eye pathology eye are reasons you may not have depth perception.
Amblyopia is another word for lazy eye and occurs in 2-4% of children. There are several types of amblyopia including refractive, strabismic, and deprivation. Amblyopia is a reduction in the vision in one eye due to a big difference in prescription, misalignment of the eyes, or the eye being prevented from receiving any vision signals due to cataracts. Depth perception is affected more in strabismic amblyopia.
Strabismus is a misalignment of the eyes when one deviates in or out while the other remains focused ahead. There are two types: esotropia and exotropia. Strabismus is common and may affect up to 5% of people. When a picture is taken of you, and your eye seems to turn in or out, you may have strabismus. Strabismus is typically treated first with glasses, patching, prism lenses, and vision therapy. If no improvements are made, it can be treated surgically.
Presbyopia is a condition where the lens and muscles inside of the eye lose flexibility resulting in blurry near vision. This condition usually occurs at or around age 40. When you experience presbyopia, if you do not receive the proper correction in glasses or contacts, you will have difficulty with depth perception. Multifocal contact lenses or progressive spectacle lenses provide the best depth perception. Monovision and OTC readers decrease your depth perception.
Unequal refractive error
If your vision is different between your eyes with or without your glasses, you will have difficulty with depth perception. For example, if your left eye sees 20/20 out of your glasses, but your vision has declined in your right eye to 20/40, you may have difficulty with your depth perception. Updating your prescription as your eyes changes is key to good depth perception.
Also, if you have untreated astigmatism, you may struggle with depth. It is common for patients with astigmatism to feel their depth perception is off after a prescription change, but the brain and eyes adapt over time. Straight lines may seem curved at first and the floor may feel like it’s coming towards you. After a couple of weeks, images appear normal once again.
Diseases of the eye such as diabetic retinopathy, macular edema, age-related macular degeneration, or arterial/vein occlusions can affect your depth perception. Permanent conditions that affect the retina are likely to affect your long-term vision. With an unequal decline in vision between the eyes, you will likely experience changes in depth perception.
Those who have a history of TBI, stroke, and Alzheimer’s disease are likely to have a decline in depth perception. Depth perception requires both eyes and adequate brain function. Damage to higher cortical visual areas in the brain interferes with the communication between the eye and the brain.
Can you improve your depth perception?
It is possible to improve your depth perception, but improvement is dependent on the reason for the inequality in vision between your eyes. If the vision in your eye is affected due to eye disease or pathology, it’s unlikely your depth perception can be improved.
If you have unequal refractive error, amblyopia, or strabismus, it is possible to make improvements, but you must be treated early in life. Most connections between your eyes and brain are made before the age of 7 or 8. If these conditions are caught after that age, little improvement will be made in depth perception. For this reason, it’s important to have children’s eyes checked annually.
Patients with amblyopia may wear a patch over one eye to force better vision from the weaker eye. Eye exercises or eye programming may be prescribed to teach the patient to use both eyes together to gain stereopsis. Compliance with patching is challenging, and many amblyopic children fail to achieve normal vision or stereopsis even after treatment.
It is possible for children to preserve stereopsis after strabismus surgery if treated early. Study data demonstrates that gains of stereopsis after strabismus surgery could be affected by the type of strabismus, the length of time the patient had strabismus, the amount of deviation prior to surgery, amblyopia, and if any misalignment remains post-surgery.
If you are an athlete, specialized sports vision training can improve your depth perception.
What is sports vision training?
The goal of sports vision training is to enhance an athlete’s vision abilities and improve athletic performance. Athletes are given an individualized training plan on a sport-specific basis to build visual skills, custom-tailored to each athlete and sport. Programs focus on increasing stereopsis to enhance performance in sports which requires rapid and accurate visuomotor function. Study data suggest that 8 weeks of training can improve binocular function. Ocular alignment and motor fusion ranges are trainable and can be improved with visual training.
Depth perception can be important in many daily life situations. It is key to your safety and helps you excel in sports. An eye doctor can test, assess and provide recommendations for improving your depth perception and your ability to see the world.