Chicken attack

[TwoDogFarm]

We had two of our chickens attack each other today and it led to this:

If we hadn't seen him when we did, we know he would have been killed. We cleaned his head up, sprayed Veterycin on him and now have brought him inside the house. At the moment, he is walking around a little bit and drinking water on his own, but I don't know if there's anything else we can do to help him more than what we've done. I don't want to lose him.

His feathers were pulled out of his head, we think he has an eye missing and he is very swollen and bloody. The attack came out of nowhere but he was being pecked in the head countless times. Please help if you can.

 

[Ol Grey Mare]

So, the bird in question is male - what is the gender of the other bird involved in the altercation? When you say he has been pecked in the head many times are you referring to this situation or is that a pattern of him being a target of aggression - if the latter has it only been the bird involved in this attack or other birds in the flock pecking him?
For now your primary focus is good supportive care to allow his body to heal -- chickens are very resilient and there is no reason, barring infection, he cannot come back from this even if the eye is, in fact, gone. Keep him calm, quiet, appropriately temperatured, hydrated and on a diet that will support mending -- monitor for infection and treat accordingly if it develops.