A dominant eye is the eye from which a person prefers to receive visual input. Generally, the person feels as if this eye is the stronger eye, and so he tends to favor it when looking through telescopes or camera eyeholes. There is a variety of simple tests that can help determine eye dominance, but many people discover their dominant eye is not on the same side of their bodies as their dominant hand. Having one eye that is more dominant than the other is common and not usually dangerous. Typically, it only becomes a problem if the vision of the weaker eye is so weak that normal vision is impossible.
Perhaps the most common dominant eye test is the Miles Test. During the Miles Test, the person extends both of his arms straight in front of him. He then brings his hands together, palms facing forward, so that only a small opening remains between his two hands. Once he chooses an object at eye level, he centers that object in the opening between his two hands and alternates closing and opening each eye to see which eye can see the object. The eye that can see the object is the dominant eye.
A person’s dominant eye plays a big role in certain actions. People who practice archery, for example, tend to rely on their dominant eye to help them best aim their arrows. The same is true of people who play other kinds of aim-reliant sports, such as darts and target shooting. At the same time, cross-dominance, which means the dominant eye is on the opposite side from the dominant hand, can be more beneficial for people who play sports like golf and baseball. This is because these sports require a side-stance, and having a dominant eye on one side of the stance and a dominant hand on the other helps their performance.
Generally, there are no hazards to having a dominant eye. Although a small percentage of the human population does not experience ocular dominance, most humans do have one eye that is more dominant than the other. Still, if one eye seems to have much better vision than the other, the person should have his eyes examined by an eye care professional. The doctor can perform an eye test to determine the cause of the vision difference and recommend the best course of action. Usually, this means wearing corrective lenses or eyeglasses, but in some instances it might mean corrective surgery.