Good morning all and thankyou for the tag
@Wyorp Rock.
@tripletfeb I'm so sorry you are having to deal with this. I regret to say that I agree with everyone that you are more than likely dealing with ocular Marek's in your flock. Everything fits the symptomology. Birds with MD have problems maintaining a normal body weight. Often they will stop eating as the disease progresses or eat like teenagers but not gain any weight. I suspect it is because of the tumors they develop secondary to MD that causes the latter. But your girl's eye is pretty much standard with OMD. I had three birds with OMD and they survived for approximately 18 months after diagnosis. They were either mostly blind with partial vision or blind in one eye. But found their way around enough to find food and water.
OMD is a painful form of Marek's. It is the same as herpes eye infections in humans so try to keep the bright light down around her. You can try giving her a baby aspirin and see if that helps.
My birds with the disease developed a sudden decline in neurological function when the end came for them. All acted as though they had strokes, one sided weakness, seizures, etc. When that happened I culled them immediately.
Banana Split. Her eyes look different than Peggy's so I'm wondering if the pigmentation isn't just 'normal' for her.
What to do? I agree with everyone also with this. Until you can get a solid diagnosis consider your flock positive for Marek's and close it. Your birds without symptoms are now carriers of the disease. There was nothing you could do to prevent this from happening. Wild birds may have brought it onto your property or even the wind carries it so other than living in a domed bubble you can't prevent it from happening.
If Peggy can survive this onset she may live for awhile for you but birds that survive the onset will develop secondary problems from the disease and perish from those. The good news is not all of your birds will die. Some will but some will survive and those birds will be resistant.
I invite you to read my article about my experiences with the disease:
https://www.backyardchickens.com/ar...-i-learned-to-deal-with-mareks-disease.76944/
I went almost 6 years without a suspicious death from the disease until earlier this year when I had a year old rooster suddenly present with emaciation and weakness/shortness of breath. Thought I was in the clear but it reminded me that it is always around.
Hang in there. Things will get better. You were saying that you didn't know what to look for in the eyes? Here is a picture of a typical chicken eye with ocular Marek's disease.
View attachment 3858035
The eye on the right is the eye with MD. The iris color will be either a sickly green or a green/gray color. The pupil will be either pin point and misshapen or I have seen some that are wide and misshapen. My bird's eyes were always the same, tiny pupil, misshaped pupil and the sickly green gray color. Since your bird is emaciated I can't help but wonder if she doesn't have internal visceral tumors along with the ocular problems. Time will tell. But I do agree with having a necropsy done when the time comes.
Blessings to you and your flock,
Becky