I was given a jersey giant rooster a few months ago and noticed one of his eyes was a little odd looking,but it still didn't look too bad. It has no progressed to where the iris is turning black, while the other eye is normal. The pupil seems to be a little mishaped too. There is some yellowing around the iris, but not much, and the bottom lid seems to be a little droopy, but no more than when I got him. I don't think it's mereks, but what else could it be?