This is a gaming term relating to first person shooters (FPS) predominantly Call of Duty. It means a gamer whose reactions and hand-eye coordination are very high. It can be a permanent state or a temporary state.
Someone who fingers a girl and then does not wash his/ her hands afterwards, then rubs his/ her eyes with said fingers, thus temporarily blinding themselves.
You fingered your girlfriend last night and now all of a sudden you're blind? It's obvious, you've got 'cod eye' you stupid tit, you should have washed your hands afterwards.