When people talk about depth perception, they’re referring to your eyes’ ability to judge the distance between two objects.
Both of your eyes perceive the same object slightly differently and at slightly different angles, but your brain can merge the two images into one 3-D image. This process is also known as stereopsis.
With this information, you can gauge how far apart the objects are, as well as how far they are from you.
You can test your eyes’ ability to provide this information at home. Here’s how to do it:
- Gaze at a picture of a circle or a ball.
- Then, hold up one finger about 6 inches away from your eyes, with the circle in the background.
- Focus both eyes on your finger. You’ll probably notice slightly hazy images of the circle that appear on both sides of your finger.
- Now, switch your focus. Keep your finger in the same place, but gaze beyond your finger to the circle.
- You should see images of your finger on either side of the circle.
If you’re having trouble, you may have an issue with your depth perception.
A number of factors can contribute to problems with depth perception. Some of the most common factors include:
Strabismus is a condition that occurs when your eyes are not properly aligned. For example, one eye might turn inward or outward. Sometimes, an eye can also look upward or downward. Some people appear to have crossed eyes, which is also a sign of strabismus.
Essentially, since your eyes may look in slightly different directions, they’ll focus on different things.
The American Academy of Ophthalmology (AAO) estimates that strabismus affects about 4 percent of children in the United States.
If your brain favors one eye over the other, resulting in one eye that doesn’t quite track properly, you have amblyopia.
Also known colloquially as “lazy eye,” amblyopia can cause vision loss in the weaker eye that can reduce your depth perception and maybe even your vision. It’s also relatively common in babies and young children, according to the AAO.
If your optic nerve is swollen or inflamed, it might affect your vision and interfere with your depth perception.
Additionally, some people are born with a rare type of nerve damage called optic nerve hypoplasia, which occurs when the optic nerve doesn’t fully develop.
Trauma to one of your eyes
If one of your eyes has been injured, you may no longer be able to see well enough to have good depth perception.
There are dozens of potential causes of blurry vision, from corneal abrasions and glaucoma to diabetic retinopathy and plain old nearsightedness.
Any condition that makes your vision blurry, even temporarily, can interfere with your ability to perceive distances and depth accurately.
You use visual cues to make all sorts of decisions every single day. And you probably don’t even think about it unless something is wrong.
When something affects your depth perception, it can also interfere with your daily life.
Here are a few common examples of how a problem that affects your depth perception may create some challenges.
Kids and learning
Children who can’t see very well may not say anything about it. But a careful observer may notice them squinting or moving their head in an effort to try to get a better view.
Some children may even have trouble learning because they can’t see the board or other teaching materials at school.
Adults and driving
People with impaired vision or no vision in one eye may worry about how they’re going to get around. The good news is that you can probably still get a driver’s license.
However, because your vision problems can affect or reduce your depth perception abilities, you may need to use some strategies to help you drive safely.
Navigating the world around you
Depth perception helps professional baseball players gauge the speed of the ball hurtling toward them. But depth perception also helps people perform simple, everyday tasks, like safely crossing a busy street or taking the stairs without the risk of misjudging them and stumbling.
If your depth perception is impaired, you may have some trouble doing those kinds of activities. You might even have trouble pouring a glass of milk.
The treatment options for depth perception issues depend on the cause of the problem.
For example, children who have strabismus have trouble with depth perception because their eyes are misaligned. So, glasses can help some of them by helping straighten their eyes.
However, other children may need surgery to straighten their eyes, and they might still need to wear glasses after the surgery.
In other cases, such as when a child has amblyopia, a doctor might recommend putting a patch over the good eye for short periods of time to strengthen the weaker eye.
If you have another type of eye condition that impairs your depth perception, talk to your eye doctor about the best possible treatment options. You might need surgery to remove a cataract, for example, or treatment for glaucoma.
Some people with limited sight in one eye but good sight in the other are able to adapt. They get enough visual information from their good eye to be able to perceive depths and make judgments based on what that they do receive.
For example, drivers can monitor factors like the relative speed of other cars on the road and how light affects cars and other objects on or near the roadway. These spatial cues can help you gauge the distance between your car and other vehicles.
There are other strategies to try, too. For example, before driving, find ways to reduce glare and anything else that can interfere with your ability to see as best you can.
This might include cleaning your windshield to eliminate any grime or dirt that can interfere with your view. You can also dim the rearview mirror and angle your side mirrors to minimize the glare from the headlights of cars behind you.
Coping strategies can definitely help, but you might also benefit from the use of certain products or services.
These may include:
Children can often benefit from vision therapy to help train their brains and their eyes to gain or regain better vision. In some cases, the training may involve physical exercises.
Eye patching can also be a part of vision therapy. Adults with certain eye conditions may also benefit from vision therapy.
If you plan to drive, you may be a candidate for specialized glasses that can help you. Your doctor may suggest using bioptic telescope attachments on your glasses to make it easier for you to see things that are farther away.
If moving around your home is a challenge, try altering the lighting and contrast in certain areas to help you see better.
For example, if you have trouble perceiving depth differences at night, try improving the lighting in and around your home, so you’re not creeping around in the dark.
Additionally, placing brightly colored tape on the edge of your stairs may help you navigate them with less fear.
If you’ve long since adapted to an eye condition that affects your depth perception, you may have already developed a toolbox of effective ways to compensate. But if you’ve just recently sustained an eye injury or developed a condition that’s affecting your vision, it’s a good idea to talk to your eye doctor.
You may not be aware of any depth perception issues yet, but your doctor may be able to examine you and determine if it’s something you should be monitoring.
It’s easy to take good depth perception for granted. But you can still live a full life even if your depth perception has been impaired in some way. You may benefit from certain treatments or vision therapy, or you may find aids to help you.
Many people with depth perception issues develop a combination of strategies to help them go about their lives as best they can. If you notice any changes to your vision, be sure to check with your doctor, just in case you’re experiencing any new problems that may need to be treated.