I have a hen, about 2 years old, who has gotten listless and sits on the roost most of the time. She seems to have lost feathers around her eyes, and the skin around her eyes seems red and maybe a little swollen. This isn't a large patch, just sort of encircling her eye. She sits with this left eye closed most of the time, and the right one open. If you say something to her, or touch her, she opens the left eye, but if you move your hand in front of it, she doesn't respond. Apparently has become blind in that eye. She doesn't have mites or lice. I had another hen like this about a month ago, did about the same thing, and got so she was twisting her head around as tho in pain. I put some Tomorrow Dry cow treatment in and around her eye, thinking this might help, but didn't, and I finally put her down because she was almost gone, anyway, and seemed to be suffering. Anyone have any idea what is wrong here?