In this function, y is the dependent variable and x is the independent variable. Variable used in an experiment or modelling can be divided into three types:  dependent variable ,  independent variable , or other.
About 70% of men have an eye dominance that matches their handedness. BUT, 30% do not. Most right handers have a dominant right eye and the bulk of southpaws a dominant left. These are the people who are well advised to shoot both eyes open (assuming that they are shooting from their strong shoulder).
Sometimes an eye may look crossed and it really is not, this is called pseudo-strabismus. Pseudo-strabismus is most often found in infants due to a wide, flat nose and a fold of skin at the inner eyelid (called epicanthal folds) that makes the eyes appear crossed (See Example of Pseudo-Strabismus).