How to Determine One's Dominant Eye. The human body is amazing because its senses are acute, and having two of anything heightens the sensitivity. Two eyes are a perfect example of this phenomenon, but both eyes are not created equal. Cameras, aiming and anything that requires a person to either close an eye or line things up uses the dominant eye. Here's how to determine your dominant eye.
Pick an object that is at least 6 feet but no more than 20 feet from you and focus only on that object. Larger objects work better to determine your dominant eye.
Stretch one arm outright and point to the object with the index finger. Eye dominance does not relate to the hands so it won't matter which hand you use. Avoid looking at the finger and focus only on the object. The finger should be blurry and two fingers may appear, but keep the object in clear focus and aim the finger at the middle of the object.
Place the other hand over one eye and keep your focus on the object. Check to see if the finger moved away from the object and note how much. Repeat by covering the other eye and note how much the finger moved. Your dominant eye is the eye not covered which had the less finger movement from the object.
Print out a "Dominant Eye Test Card" and cut out the middle square. Hold the card as far away from the face as possible with your own hands and focus on something in the distance seen through the hole in the card.
Bring the card towards the face slowly, keeping the object in focus. Don't loose focus on the object and the card will naturally come towards the dominant eye for you to easily determine the dominant eye.