Sometimes pied birds tend to have 'cracked' or 'split' eyes, which is where parts of the eye are shadowed/black. It can be a little bit to nearly the whole eye. If that's not what you're talking about, then I don't know. But I can say split eyes has nothing to do with how good a bird is It's like when you have a blue bar you expect it to have bars; it just happens.
It means that he got a bug in his eye and doesn't have a finger to get it out with!
Just kidding of course. Some will tell you that this has some great hidden meaning. They will give you all kinds of fancy terms like circle of correlation, etc. to impress you. Bottom line is that you need to decide what makes sense to you and go from there. If you decide that it is an important sign then I guess it is...to you.