Unfortunately, the eyes of baby chicks are very appealing to other chicks. They're shiny and bite-sized, and easy to distinguish as something interesting to peck at. They look exactly like a little edible bug would look - like a beetle. Our Brahma babies were pecking each other in the eyes like crazy. They're about 4 days old (I think, I'm horrible with time). Eyeballs and beaks - they peck. All three have little red 'dots' on their beaks from pecking each other there, and their eyes look a bit sore. BUT...they are improving.
It has gotten much better since I threw in two polka-dotted watermelon fabric swatches. Fabric is bad (obviously) for chickens to eat, but if you buy thick fabric they're not going to eat it anytime soon - they're babies. Ours have had theirs for two days and it's still not torn. They peck at that together now instead of each other. I'll remove it when I see they're getting old enough to tear and possibly eat bits of it, but for now I'm leaving it there (contrary to any "suggestions" by others) - they're fine with it and it's definitely keeping them away from each others ouchy bits.
I also put a speckled rubber dog toy in there and they sort of push that around sometimes too (more interest in the fabric though).
good luck - I think it's normal chick behavior - eyes are tasty looking for them.
I assume they have a plentiful supply of chick starter too?
If I were a brand new chick with no life experience yet - and I saw something black and tiny and shiny-glowy, and moving around, I'd peck at it too. =)
[Edited to add] If they start pulling and tearing at each other (grabbing and seriously injuring) rather than pecking, I would remove the offenders and have chick-ka-bobs for dinner.
