You may be dealing with Mareks.It's really weird she doesn't have the symptoms of worms or infection her comb is normal but her eyes look a little cloudy and she doesn't seem to be able to see. I have been giving her antibiotics and a worm medicine and will see how that works... still force feeding with soaked food and water.
I say this because of the cloudy eyes, blindness, staggering, and seizures.
I've never dealt with this. I can't give you any advice. I know it is highly contagious, but can affect some flock members and not others. There are several threads concerning Mareks, that you can research.
On the other hand, these can be symptoms of heat stroke in a human. At this point, she doesn't appear to be recovering. If a vet is an option, I'd have one evaluate her, and help you make a decision about euthanasia. I'm very sorry. I wish I could help.