Yep, isolate it immediately. Does she show any other symptoms? (e.g. nasal discharge or rasping breathing?). Either way, you may wish to consider cleaning the eyes in a mild saline solution (or luke warm water) and then administering antibiotic eye drops (e.g. Neosporin Ophthalmic Ointment / drops) and add vitamin supplements to the water - helps the immune system to fight whatever is going on. If there are other symptoms, then giving a broad spectrum antibiotic to the water may either address her problem, or at worst fight off any secondary infections. Personally, i only do the latter if the chicken is showing symptoms of general illness - lethargy, not eating or running around doing "chicken things".