How to Find Your Dominant Eye and How It Affects Your Vision
September 1, 2024 • 5:30 PM
Humans are typically made with two of almost everything: two hands, two feet, two arms, two legs, two ears, and two eyes. This not only makes us look symmetrical, but it’s also a clever survival tactic. If one gets injured, we have a spare.
In some ways, one even acts like a spare. Take, for example, your dominant hand. If you’re right-handed, then your right hand does more work than your left hand. It writes, eats, throws, and catches while your left hand hangs out. Sure, your left hand can help out when you need it, but it’s definitely not doing 50% of the work.
The same is true with your other duplicate body parts: One side is often working harder than the other. It’s a phenomenon known as laterality. And when it comes to your eyes, it’s called ocular dominance. You have a dominant eye, just like you have a dominant hand.
Here’s what it means to have a dominant eye and how to determine which of your eyes is dominant.
What Is a Dominant Eye?
Your dominant eye might sound like it’s the eye with better vision (or better visual acuity, as they call it in ophthalmology), but it’s not. It’s more like the eye with better communication skills.
Your dominant or preferred eye sends more accurate information to your brain. So, when your brain is trying to determine how far away an object is or where an object is located in relation to you, your dominant eye does a better job of pinpointing the object’s location and sharing that information with your brain.
While two-eyed or binocular vision is best for depth perception, your dominant eye has more accurate depth perception on its own than your non-dominant eye. It can also relay more accurate information about the details of an object, like the object’s texture, color, or pattern.
So, your dominant eye is clearly working harder to keep you in the know. But that doesn’t mean your non-dominant eye isn’t doing anything. It just means it’s doing less.
Maybe your brain gets 70% of its information from your dominant eye and 30% from your non-dominant eye. That extra 30% is still helpful and creates a more accurate picture of the world around you, which is why binocular vision is always better than one-eyed or monocular vision.
Why Do You Need to Know Which Eye Is Dominant?
Most of us don’t. We use two eyes for the majority of activities, and even if one eye is doing more of the work, ultimately the eyes function together to help us see things clearly. But there are some activities and visual conditions where ocular dominance plays a bigger part.
Activities Affected by Ocular Dominance
If you’re ever doing a one-eyed activity — like looking through the viewfinder on a camera, the eyepiece on a telescope, or the sight on a crossbow — using your dominant eye will help you more accurately set up your shot.
Knowing which eye is dominant can also help you achieve proper alignment in sports. You’ll learn how to angle your body so that your dominant eye — not just your non-dominant eye — is able to see the goal or target. This will enable you to set up a more accurate putt in golf, hit a moving target in archery, or catch a flying ball in baseball.
Visual Conditions Affected by Ocular Dominance
Sports and photography aren’t the only things affected by ocular dominance. Your eye doctor may need to determine your dominant eye to correct certain vision problems.
Amblyopia (or Lazy Eye)
Amblyopia, sometimes called lazy eye, is an extreme example of ocular dominance where the brain stops listening to the non-dominant eye entirely and relies only on the dominant eye.
Over-reliance on the dominant eye makes vision in the non-dominant eye worse and worse. So, a healthcare professional will need to intervene to teach the brain to rely on the non-dominant eye, too. This is typically done by having the patient wear an eye patch or use eye drops that blur their near vision in the dominant eye.
Amblyopia is most common in children. And kids with other eye health issues, like strabismus (sometimes called crossed eyes) or childhood cataracts are most at risk.
In these cases, an eye doctor will treat the underlying conditions as well. Strabismus may require glasses, eye muscle exercises, or eye muscle surgery. Childhood cataracts may require cataract surgery to remove the cloudy lens of the eye.
In most cases, children who receive proper eye care for amblyopia will achieve much better vision in their non-dominant eye. And the younger children are when they start treatment, the more successful it will be.
Monovision Contact Lenses
If you have presbyopia — a normal, age-related decline in your close-up vision that causes many older people to need reading glasses — then your eye doctor may prescribe you monovision contact lenses. At which point, the doctor will need to determine your dominant eye in order to provide the best vision correction.
With monovision lenses, you’ll wear one contact in your non-dominant eye to correct your near vision. You’ll use your dominant eye for distance vision because this will give you better depth perception.
If you already have perfect distance vision, then you won’t need a contact lens in your dominant eye. But if you need correction for your distance vision and your near vision — like if you already wore single-vision lenses before your presbyopia set in — then you’ll wear two different monovision contact lenses.
You’ll wear one contact in your non-dominant eye to correct your near vision and a different contact in your dominant eye to correct your distance vision.
Monovision contact lenses are often prescribed to people who wear progressive lenses in their glasses. Like monovision lenses, progressive lenses also correct your near and far vision at the same time. However, they work differently, so you don’t need to know your dominant eye for progressive glasses.
Both monovision contacts and progressive lenses take some getting used to. But once you master them, your eyes will work together to help you see clearly at every distance.
How to Find Your Dominant Eye
There is some correlation between eye dominance and hand dominance. So, if you’re left-handed, you’re more likely to be left-eye dominant. And vice versa: If you’re right-handed, you’re more likely to be right-eye dominant.
But your dominant eye can also be on the opposite side of your dominant hand. So if you really want to know which of your eyes is dominant, you should perform a dominant eye test.
While most people will have one eye that’s clearly dominant over the other, it’s possible to have cross dominance, which is the eye-equivalent of being ambidextrous — with both your eyes working equally hard. You can also have mixed ocular dominance, which means one eye is better at one thing (like depth perception) while the other is better at something else (like color perception).
So, if you’re still not sure after doing the following eye dominance test, ask your eye doctor during your next eye exam.
Circle Test
This is our favorite eye dominance test to do at home because it’s very similar to the card test done at your doctor’s office using a card with a small hole in it. Except with this simple test, you don’t need any equipment.
Begin by bringing your thumb and index finger together to make a circle. Then, pick a distant object, like a light switch or a picture frame on the wall. Keep both eyes open. Hold your arm straight out in front of you, so that the object is centered in the circle created by your thumb and forefinger.
Now, close your left eye. Does the object remain centered in the circle?
Open your left eye, and repeat it on the opposite side.
Close your right eye. Does the object remain centered?
If the object was centered when your left eye was closed, then you have a dominant right eye. If it was centered when the right eye was closed, then you have a dominant left eye. And if it stayed centered no matter which eye you closed, then congratulations: You may have the rare trait of being cross-dominant.
Is It Possible To Have No Dominant Eye?
Some people don’t have one dominant eye, but this is the exception and not the rule.
Sometimes, a person won’t show a significant difference between their eyes during sighting tests, which usually indicates mixed eye dominance. With mixed dominant eyes, a person will sometimes switch between their left eye and their right eye for dominance throughout the day. But again, this isn’t common.
In the same way that some people don’t have a dominant hand — also known as ambidextrous — some folks are “ambidextrous” with their eyes. In these cases, it can be hard to find a preferred or dominant eye using conventional testing, and it might not be necessary to test at all.
Can Your Dominant Eye Change?
As it turns out, eye dominance can change. It tends to stay consistent after a person hits puberty, but some people notice one eye getting weaker and the other eye compensating later in life.
This may happen in middle adulthood, and it’s sometimes only temporary. For example, some older adults report that when their eyes are tired, they rely more on their non-dominant eyes to focus.
What Else Can Affect Eye Dominance?
One key factor that can influence eye dominance is an issue with the muscles in your eyes. This condition is called strabismus, and it comes in multiple forms, including esotropia (when the eyes turn inward), exotropia (when the eyes turn outward), and hypertropia and hypotropia, which cause one eye to turn upward or downward, respectively.
In cases of hypertropia or hypotropia, a person develops what is sometimes called a “lazy eye,” although this term is not considered polite. One eye is weaker than the other due to a neurological or muscular problem, and the other eye will compensate as a result.
Some people with hyper- or hypotropia wear an eye patch to re-establish balance in their vision, as the unfocused eye can make it hard to see objects in the center of their field of view.
It’s also worth mentioning that an eye injury can affect eye dominance, too. If one eye is weakened by physical trauma, the opposite eye might compensate. Finally, cataracts, glaucoma, and other eye conditions that develop with age can also cause changes in eye dominance, especially when they go untreated.
Seeing Is Believing
Once you’ve done a dominant eye test, it’s easy to visualize how one of your eyes is giving more information than the other. That dominant eye is a hard worker and an excellent communicator — always keeping your brain up-to-date with the most accurate information about your surroundings.
But your non-dominant eye deserves love too. It may not be providing as much information as the dominant eye, but it’s still doing its part. Much like how most activities are easier to do two-handed, most things are also easier to do with both eyes open.
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Sources:
Visual Acuity | American Academy of Ophthalmology
Amblyopia (Lazy Eye) | National Eye Institute
Strabismus | Johns Hopkins Medicine