Eye dominance (sometimes called eyedness) refers to the tendency to use one eye more than the other in certain tasks involving precise hand-eye coordination and a reasonably distant target. It is especially important in sports which require aim, such as archery, darts or shooting sports.
In normal binocular vision there is an effect of parallax, and therefore the dominant eye is the one that is primarily relied on for precise positional information.
It is somewhat analogous to right or left handedness, however the side of the dominant eye and the dominant hand do not always match. Approximately 80% of the population is right-eye dominant; in a small percentage of the population, neither eye is dominant. Eye dominance can be slight or profound; highly profound cases are sometimes caused by amblyopia.
Testing eye dominance
There are a number of ways to test eye dominance, but the simplest is to extend your arm out in front of you. Connect your index finger and thumb together making a circle like shape. Focus on an object, and ensure that the object is in the middle of the circle. Now, close an eye (eg, your left), if the object moved, that is your dominant eye. The movement should be noticeable. For an alternative method of testing, make the same shape with your hand, and focus on a distant object. Bring your hand towards your head while keeping the object in the circle. Whichever eye your hand is in front of is your dominant eye.
