This phrase can have one of 3 meanings the Metaphorical sense: meaning one aggressive or harmful action commited against a person is moraly equal to that person commiting an aggressive or harmful action towords against his or her aggressor. The other meaning is the Entirely Literal sense of the phrase: in which one person has there eye taken by an other and so then takes that persons eye as retribution. There is also the Half Metaphorical meaning: which is one action that is aggressive or harmful towords a person or a body of people makes it moraly acceptable to take that aggressors eye as retribution
"Thouse barbarians have raped all of the virgins of our village so we must go over to their all-male camp and rape them because that is the way of an Eye for an Eye"
"Oww!! holy shit!! that guy just took my eye, what the hell!! I'm gonna take his eye because that's fair, its an eye for an eye!"
"I can't belive you just stole my last rolo Skippy!, that's it I'm taking your eye, *struggle* Bloody hold still!! *gauge* *pop* There we go. An eye for an eye skippy."