How long have you had her, and have you added any new birds recently? Her eye appears to have conjunctivitis and a sinus infection which are common with MG (mycoplasma gallisepticum.) It is a chronic disease and may be treated with certain antibiotics, such as Tylosin and a few others. It may return later with stress. It would be best to close your flock to new birds. You can get a diagnosis by testing or a necropsy by your atate vet.
How does she smell around the face? Could she have been stung by something in the face? Infectious coryza can also be possible, and it smells bad, and symptoms can be more serious. Terramycin eye ointment for a feed store may be applied to the eye 2-3 times per day after cleaning the eye with saline eye wash or a clean wash cloth. If there is pus in the eye, it needs to be removed.