I would look into her eyes for any drainage, bubbles, or gunk. Putting some saline eye drops into both eyes might help if it is some sort of irritation. Bring her inside to a basket or crate near water and feed, in case she is having trouble finding them with her eye issue. Look at your air circulation inside the coop for ammonia odors or dust, and maximize air movement from one end to another, especially if more openings are needed. Is she moving both legs and wings normally, and walking okay? While I worry that she may be dehydrated, there is also a slight possibility that something more serious is going on. Was she vaccinated for Mareks? Is her neck behaving like wry neck or torticolis? If you can get some chick vitamins with electrolytes in her water for a few days, that might cover wry neck, vitamin deficiency, or dehydration.