Happy wrote: ↑Tue Aug 21, 2018 10:41 pm
I've noticed her eyelids getting very droopy and realized that she's not seeing very well or not at all out of her left eye. Her depth perception is way off. She walked right off the top step of the deck tonight and tumbled down. Might this be why they pick on her?
Yes, a chicken with
anything wrong with it, even something very minor, will be ostracized or outright picked on. The other chickens can smell something amiss, quite literally.
Happy wrote: ↑Tue Aug 21, 2018 10:41 pm
I sure hope it's not the result of their bullying.
No, highly unlikely, you said there was something always a little different about her. Different means weakness, illness, genetic issues. Other chickens would have known this long before humans would have noticed. Different is not OK in a chicken's world. Different attracts predators and endangers the whole flock. The different ones gravitate to us as people, because they need company/a flock, and we gravitate to the 'different' ones because they are friendly and we subconsciously sense that they need us.
Injury or illness comes first, THEN bullying. I've never seen it otherwise. It's why our favourites never seem to live to old age--they seem off because they ARE off. The lowest in the pecking order are always there for a reason.
Happy wrote: ↑Tue Aug 21, 2018 10:41 pm
I feel bad that I'm just noticing this.
For now she seems happy enough so I guess I will just continue as we've been doing.
Please don't feel bad, it's very likely something that has been brewing for a long time, perhaps all her life, and is only now just getting bad enough that it's become obvious to you as a lowly human

Remember, chickens are MASTERS at hiding illness and disability, because they are a prey animal. Blind chickens with a full crop will peck randomly at the ground when other chickens are nearby, not because they're trying to find food, but because they're genetically programmed to pretend there's nothing wrong so they won't be driven from the flock and/or killed. Generally, by the time a chickens' illness or disability is noticeable to a species that doesn't pay attention to such things (people), it's severe and well-established.
Happy wrote: ↑Tue Aug 21, 2018 10:41 pm
Has anyone had a seeing impaired chicken?
Yes! Several! My very first (and probably not a great example) was a rooster named B**ch. Thus named because at first he was a model rooster, beautiful and great with hens and people, until an unfortunate peck skewed his one eye and his brain. His one pupil looked like a sideways number 8. After that, if he saw a person (or anything else moving) first with his bad eye, they would get an unstoppable flogging. One time, I broke a bucket over his head trying to get him off me. He flopped around for a bit and I was sure I had killed him

. Then he suddenly jumped up and walked off like nothing had happened. I walked away and went about chores, and then suddenly got his spurs in the back of my calf. THEN, he went after my elderly silkie hen, jumped on her and pecked her in the head over and over and over. I yanked him off her and isolated him. Mama Silkie died the next day from her injuries/shock. I took his head off. He might not have been responsible for his violence, but I still have the leg scars. I still remember how TASTY and satisfying his tough old carcass was. I've learned a lot since then. Never run, or even walk, away from an aggressive rooster. Blind, brain damaged, or not. Act like you own the place. Because YOU are head chicken, and this attitude can not only prevent aggressive roosters, but also can teach your hens not to bully a disabled one! But that's another story for another day.
The second blind chicken I owned, was "Mama White", the last of my hatchery leghorns about 2013 or so. She went blind in her old age. In her second last year, she could still seem to see light, shadow and shapes, and got along OK out with other birds with a bit of extra attention like your girl is getting. Completely blind in her last year, I kept her by herself for a short bit in a huge cage, keeping food and water always in the same place. They CAN smell where food and water is, but she was old and I didn't want to make her hunt for it, it hurt my heart. She enjoyed the personal attention, and I even raised some chicks in with her. At first she needed to be lifted on a roost at night and off in the morning, but if I didn't do it, she would huddle looking miserable on the bottom of the cage. Until she learned to bump it with her chest and step up :) One of the chicks became her buddy, and never picked on her even as an older adult. They were inseparable until the end, and Buddy Chick never left Mama's side. I was actually able to put Mama White and her buddy back out with the other hens for a while. Buddy hen would lead MW out of the cage (the door was always open), calling quietly to her like a mother hen to a chick, and then back into the cage at night. MW died in her sleep at 7 years old, and her Buddy hen wasn't long following. The two of them had a system like I'd never seen before or since...so, if your special hen has a friend she gets along with, keep them together!
The third was Owl. Old Owl the rooster started to lose vision in his middle years. I wasn't quick enough or careful enough about making sure he was safe, and his low vision was his undoing. At the age of 8, he tried to perch on precariously leaned pieces of plywood, and he and them fell flat: him stuck underneath, and dead the next morning when I found him

. I believe in, and usually try to practice "survival of the fittest" with my chickens, but some just have my heart, or at least "Coop Cred", and I've tried to be a little more observant since then.
Then there was Buddy Rooster. (yeah, I've had several chickens named "Buddy".) He was ALWAYS weird; none of the hens liked him at all, always drove him away and even quit laying when I locked them in with him. I could never put my finger on why nobody like him. And then one day he just suddenly went almost totally blind after an unfortunate hen peck to *just* the right spot on his head. One day he was completely fine, and the next he was neck out, 'hunting' as if in a pitch dark room, bumping into walls and bleeding from both ears. Never got his sight back, but again, food and water always in the same spot, and he got along just fine. As a matter of fact, since he was no longer trying to breed the hens, they decided he was OK and he finally had his little flock! Hens that hated him before now happily slept next to him. Babies would snuggle under his feathers after their mothers started turning them away, and indeed, I "used" him to save orphaned, or cold chicks more than once. He couldn't mother them, but he happily spread his huge wings and kept them warm and took them to food until they were strong enough to go find food on their own. After he lost vision, he was actually a MORE productive flock member, in my eyes, anyway. He died very suddenly one night, at only 4 years old. He was a beautiful, gentle, huge, red splash Orpington/Chantecler, and I still miss him.
Like I said, the special ones don't generally live to old age

I currently have two "sight impaired" chickens. One is a four year old UGLY hen that came from Performance Poultry as a day old chick. She was supposed to be a Jersey Giant, but has the skin colouring of an Australorp, and is ugly with ratty, stick-y-up-y feathers and is smaller than a sexlink. She only has one good eye. The bad eye has always been a tiny, shrivelled, ugly thing like a dried currant, and she has no inner eyelid on that side, so every couple of weeks there is some dead tissue/pus on that side. Apart from her appearance, she is strong and alert, constantly swivelling her head to keep watch. Unless I'm close, and then she keeps her blind side to me. I feel strangely honoured that she trusts me that much. She stays close to the barnyard, especially now that she is mothering chicks for the very first time, but has no problems getting around; she's just nervous about being blindsided and startles easily. She's not top of the pecking order, but she holds her own. For now. And now is mothering four chicks
Also, I have a 1 1/2 year old rooster that lost sight in an eye as an adolescent, during a dominance fight with a much older rooster just after I got the stupid douchebag. He's completely blind on one side, blank eye with no pupil... but the other eye works fine. He has adapted very well, and also gravitates to me. The majority of the roosters I have, see me as THE head rooster and will not mate or even crow in my presence, which works in the favour of some of the guys on the sidelines. One-Eye watches for me to come outside, follows, and hops on any hen in his path (they are quite willing) unmolested.
Low vision is very manageable, if that's the only thing going on with your hen. It sounds like you're doing all the right things to keep her safe and happy

Make sure there is food and water for her when the others are done (and that she knows where it is), and that she continues to have friendly company (you and/or a friendly buddy hen) as her condition gets worse (It WILL) and prepare yourself for the fact that she will not likely have a long life

, but be reassured that she has had the BEST life any hen could ever have!
Oh, something else to consider--egg laying. Any reasonably healthy hen, young or old, blind or sighted, will lay eggs if they perceive light for certain hours per day on the top of their head. Even hens born without eyes will lay eggs if they get the required hours of light (possibly due to "sensors" in their combs or due to optic nerves even if eyes are nonfunctional?). Egg laying tends to be unusually upsetting to hens that are vision impaired, and if the hen has some congenital anomaly, egg laying can use reserves she doesn't have to spare, especially if older. I would advise against encouraging a pet blind hen to lay eggs. If she's in the coop, either she will or she won't, but if you bring her in the house, it's easy enough to control. 12 hours of light or less as needed, and she won't lay. If light is diffuse off to the side, she probably won't lay anyway. And, no matter how much you love her, you likely won't want her passing her possibly genetic blindness on to her chicks, so it's a bad idea to hatch her eggs. Anything she lays is breakfast. Generations of "special" chicks is not a road you want to take. I did it once, with the last egg a "special" 16 year old hen named Googles ever laid. Googles Junior was...weird. She raised a weird clutch of chicks. All now dead, including GJ, before the age of 2. That's not acceptable to me.
WEIRD attracts humans. It's why we have great danes, pugs, mastiffs and chihuahuas and blue merle anything, all descended from wolves. Just because we CAN and we WANT, doesn't mean we SHOULD.