Similar to handedness when persons one hand is superior to the other, ocular dominance is a term which describes the tendency to prefer visual input from one eye over the other.
How To Determine Your Dominant Eye?
1. Select a relatively small object such as window of a distant building or a cup of coffee on your colleagues desk.
2. Stretch both arms in front of you towards the object.
3. Use your hands to create a small triangle.
4. With both eyes open visually place the object within the triangle of your hands.
5. Close your left eye. (Is the object is still visible?)
6. Close your right eye. (Did the object jump away?)
If you answered 'No' at point No.5 and 'Yes' to point No.6, then you are right eye dominant. And vice versa if the answers were the opposite.
In fact a small percentage of world's population has no ocular dominance, which means that both eyes are equally strong. If so you are among the lucky ones!
Now when I know my dominant eye, what's next?
While for target shooting it is always advised to use your dominant eye for aiming and your dominant hand for triggering this is not always true as some people might belong to the group who are 'cross-dominant' that is when your dominant eye and your dominant hand are the opposite.
I am Cross-Dominant. What should I do?
The solutions differ based on your preference of disciplines.
The solution might be relatively easy as it is actually possible to shoot in a 'cross-dominant' position when your weapon for example is held in the right hand and left eye is used for aiming. One important note here is to understand if such position will be comfortable for you as there might occur additional neck and muscle strain.
The solution might not be as easy. While your dominant eye will provide you with a sharper and more clear sight picture especially when practising with open sights, your dominant hand allows you to have a better trigger control. Since it is not possible to shoot in a 'cross-dominant' position, that is to lean all over the cheek plate with your head a trade-off will always be there.
In such case as a rule of thumb it is advised to start with your dominant eye and see if it works for you.