I thought about posting this in the genetics/breeding section, but I would figure that perhaps some people with veterinary experience would have their attention called to an abnormality like this more so than breeders who would simply write it off as a fault and cull the bird. I have now 2 cockerels that have displayed this same sort of iris staining as they age. It is not the result of physical injury, the birds appear to be in great health, and when the chicks were born the eyes were normal (although both had blue eyes). As they aged, the irises get stained brown from the pupil outward, until the entire eye is brown with a ring of gold around it. Here are pics of my two birds. Has anybody ever seen this?