5) I am really not sure on this. My wife was sure that one particular cockerel was near sighted but observing him over the past year he seems to have unimpaired visions to me. Others could be in the same category. I don't really know how to administer the chicken vision sight test.
Obviously you need to purchase the chicken eye exam poster which has pictures of various insects that get progressively smaller and see how far down the line the chicken can identify from a reasonable distance.
