Dominant Eye

What does having a dominant eye mean?

Having a dominant eye is where your brain prioritizes one eye’s input over the other. It’s a common and normal trait that most people have. It works somewhat like how most people have a dominant hand or foot.

When you’re looking at something, your dominant eye is the one your brain relies on most. The input from the nondominant eye is “suppressed.” It’s like cooking using two pots on your stove at the same time and putting one on a back burner or heating element set on “low.” You can still monitor it and make sure it’s not burning, but it doesn’t demand your full attention.

Eye dominance isn’t a constant. You might prefer to use your nondominant eye for certain tasks. And there’s evidence that your brain can automatically switch which eye is dominant to match the situation. Most people don’t notice the switch because the handoff is usually smooth and subtle.

Why does one eye become dominant?

Having two eyes that work together — known as stereopsis, or informally as “stereovision” — is an important vision trait most people have. The difference in angle between your eyes may be tiny, but your brain uses the difference to calculate distance, which is necessary for depth perception.

But your brain also wants to be efficient. Eye dominance lets your brain prioritize input so it doesn’t have to expend resources constantly to keep up with both. And because there are many reasons why one eye might be dominant in a specific situation, there are a few different subtypes of eye dominance.

What are the types of eye dominance?

There are different types of eye dominance for different purposes. They vary depending on what your eyes are doing at the time and what you’re looking at. The types are:

Motor (sighting) dominance

Motor dominance refers to whichever eye takes the lead when you direct your gaze at something (which is why it’s sometimes called “sighting” dominance). This is usually what people mean when they talk about eye dominance.

Sensory dominance

Sensory dominance describes when your brain has one eye take the lead when both eyes provide competing information. To test for this, eye care specialists use a binocular rivalry test. They use a device that shows separate pictures to each eye. The picture you see clearest is the one shown to the eye with sensory dominance.

Acuity dominance

Acuity is how clearly you see. Normal acuity is known as “20/20 vision.” But some people have eyes with different acuities. When you do, the eye with better acuity might take the lead in some situations.

How can you tell which eye is dominant?

To figure out if you have a dominant sighting eye — and most people do —you can use the following steps, which are known as the Miles test:

• Pick an object far away from you, like a light switch, clock or picture across the room.
• Use your hands to create a small hole and then extend your arms out all the way.
• Look at the object through the hole made by your hands.
• Close your left eye. If you can still see the object through the hole between your hands, your right eye is probably the motor-dominant eye. If you don’t still see the object after closing your left eye, then your left eye is probably motor-dominant.
• Try switching which eye is closed a couple times to confirm.

But not everyone has a dominant eye. Research on it is mixed, but one estimate indicates just under 7% of people don’t have a preference when asked about how they use their eyes for various tasks (looking through a telescope, looking through a keyhole, etc.). They might test as dominant for one eye, but it becomes a question of habit vs. preference.

It’s also important to remember that when you test your own eye dominance, you’re probably testing motor dominance only. To figure out sensory or acuity dominance, you’ll probably need to see an eye specialist for specific testing.

Do your dominant hand and eye have to be on the same side?

Having a dominant eye and a dominant hand on opposite sides is known as crosshandedness. It isn’t rare, but it also doesn’t happen for most people. The type of hand dominance can also vary. Some people have inconsistent hand dominance, meaning they write with one hand, but throw with the other.

A 1999 study that analyzed 10,635 people broke down the preferences for writing, throwing and eye dominance. The findings from that study break down like so:

So, it isn’t rare to be consistently right-handed and left-eyed. But if you don’t use your right hand consistently and are left-eyed, you’re part of a group that makes up less than 2.1% of people, or nearly 169 million, worldwide.

Is it rare to be left-eye dominant?

Most people are right-eye-dominant, but left-eye dominance isn’t rare. It’s just less common. About 30% of people have left-eye sighting dominance.