A good eye is returned with a good eye and a bad one with a bad. When someone acts in good they receive good if they act in bad they receive bad. We cannot do wrong in the name of righteousness. This is to say, that if we cause sin in the name of good it is still sin and causes more sin. Sin is sin no matter it's intentions. If you 'take' a good eye one would do a good deed to another, if you take a bad eye you are doing an injustice to another. You do not do a good deed and receive an injustice for that deed. You may receive injustices for other sinful acts, from a sinful person, when you do a good deed for them, but that is not the effect of the good deed, that is an effect of a past wrong deed.