No chicken likes you to mess with their eyes, but you need to drip some saline or water, or use an eye wash into her eyes 2-3 times a day. Then apply either the Terramycin or plain Neosporin/triple antibiotic ointment into the eyes. Something has injured her, possibly a hawk, raccoon, dog, etc. can anything get into the coop or run or dig under the floor? Did you answer if you have a rooster? They sometimes grab the back of the neck to mate. Saline is easy to make to use on her wounds, or you can use a wound spray such as Vetericyn. Look her over well for any other hidden wounds. Separating her in a wire dog crate with food and water inside the coop, or in a basket inside your house would be good. Do they normally pick on her or has she been having any balance or walking issues? Mushy wet chicken feed, scrambled egg, canned cat food or tuna are good things to tempt her to eat. Fluids are more important, so you may need to dip her beak in a small cup to get her started on the water or the food. Let us know how she is getting along.