So in the game Dynasty warriors he is featured in there being shot by an arrow to the eye in; I believe, a battle against Lu Bu.
The game doesn't show him eating it but from before I've seen it is mentioned that he ate his eye.
You're making a big assumption about the historical veracity of Dynasty Warriors, which is a heavily fictionalized version of a book that was already a heavily fictionalized account of that time period. He ate the eye in the book as a demonstration of how badass he was, sure, but there's no actual historical proof that the real man did anything of the sort.