Pardon me, you mean "dominant" eye?...
To know which is your dominant eye, you can do it easily yourself or by the help of another person.
1. Try to look something/object clearly infront of you by using a small "tube" (you can use folded paper and such, about 1inch dia.) or even with your two hands (make a "tunnel" with them-in line within your eye to the object).
After you can see clearly the object in a moment, try to close/blink one of your eyes. (don't move the "tube/tunnel). If you can see the object with your right eye, so that's your dominant eye....and vice versa.
2. Ask another person or your buddy stand in front of you. Look his face through your "tube" and ask him to see which one of your eye can be seen by him. If he see your right eye through the "tube", so that's your dominant eye.
(You can also try this methode infront of a mirror by yourself).
*hope you undertand my bad english...