How to Find Your Dominant Eye

A dominant eye test can tell you which of your eyes is the dominant one. Your dominant eye is the eye that sends slightly more information to your brain. It tends to be the eye that gets the most use.

You may notice this preference when you use a camera, microscope, or telescope. It is also referred to as "ocular dominance."

This article discusses how to find your dominant eye and when eye dominance can make a difference.

The Dominant Eye Test Procedure 

Most people automatically use their dominant eye when looking through a camera eyehole or a telescope. But you may still have a hard time deciding which eye is dominant.

If you're curious, you can take an eye dominance test. There are several techniques for determining your dominant eye. There are tests that involve the use of a hole in a card, and others that involve the use of pinholes and rings. The Miles Test, described below, is considered to be a good indicator too.

1. Extend your arms in front of you with your palms facing away.
2. Bring your hands together, forming a small hole by crossing the thumbs and forefingers.
3. Choose a small object about 15-20 feet away from you. With both eyes open, focus on the object as you look through the small hole.
4. Close one eye and then the other. When you close one eye, the object will be stationary. When you close the other eye, the object should disappear from the hole or jump to one side.
5. If the object does not move when you cover one eye, then that eye is dominant. The eye that sees the object and does not move is the dominant eye.
   

Does Eye Dominance Matter?

Eye dominance has no particular medical significance, and it may make no difference in your life. For most tasks, it doesn't matter which eye is dominant. Most people instinctively use their dominant eye for things like:

• Using a microscope
• Looking through a telescope
• Performing other tasks that involve closing one eye

It is, however, important to know which eye is dominant if you participate in certain sports that require accurate aim. Examples include:

• Archery and hunting: Knowing which eye is dominant may help you with your accuracy. If you try aiming with your non-dominant eye, your target won't be in the right place. You should shoot with the hand that matches your dominant eye. For example, if you have a dominant left eye, you should shoot with your left hand, and vice-versa.
• Baseball and Golf: These sports require good aim. Your accuracy depends on using your dominant eye when hitting the ball.
• Photography: If you aren't using your dominant eye to look through your camera's viewfinder, you may see certain details that will end up outside of the frame in the final image. Looking through your camera's viewfinder with your dominant eye ensures that the image you see is the one that you'll capture.
  

It is possible to change eye dominance through the use of patches and other techniques, but it is difficult and takes time. If you are considering monovision correction to reduce the need for reading glasses or bifocals, your eye dominance will need to be considered.

Eye Dominance and Handedness

In general, eye dominance goes along with handedness. In other words, lefties' left eyes are more likely to be dominant while righties' right eyes are likely to be dominant. But there are many exceptions to this rule. For example, according to one study, about 35% of right-handers and 57% of left-handers are left eye dominant.

Things get even more complicated if you're ambidextrous (a switch hitter), or use different hands for writing and throwing. According to one review, 28.8% of left-handers and 1.6% of right-handers by writing were inconsistent for throwing. For this group, it's almost impossible to correlate handedness and eye dominance.

Is It Possible to Not Have a Dominant Eye?

Most people have a dominant eye, just as most people have a dominant hand. In rare cases, a person's eyes may be balanced, meaning neither one is dominant. That means the person can use either eye when performing tasks in which most people use the dominant one.

It is much more common, though, to have a variation in how dominant your dominant eye is. For example, some people may have one eye that is only slightly more dominant than the other. Others may have one eye that is much more dominant than the other.

It is also possible to have mixed ocular dominance, which means one eye may be more dominant for certain tasks, while the other is preferred for other tasks. 

Summary

Your dominant eye is the one that sends the most information to your brain. Some people have one eye that is much more dominant than the other, while others have an eye that is only slightly more dominant. You can find out which of your eyes is the dominant one using a simple at-home test, described in detail above.

Ultimately, it doesn't matter which eye is dominant, but for certain sports and professions, you may want to find out which eye you naturally favor. Using your dominant eye to aim or look through a viewfinder can improve your accuracy.