My 1.5 year old Delaware has a pupil that look completely different for the other and the other hens. She has no other symptoms, she eats, she plays, she lay eggs daily and seems very happy. I bought her in tractor supply and I kept her up organic. She only eats organic food and I don’t give her medicine. I was under the impression that the chicks are vaccinated when we buy them there. I read about Mareks, but I can’t see any other symptoms and my child told me that she’s been like that for at least four months. (Shame on me, I didn’t listened to him). I don’t want to kill her since she seems fine, the other girls are okay (Rhode Island). My chickens are backyard flock in the middle of the city, so I don’t know how they could’ve catch a desease. Please, any advice can help we are very attached her.