Hello, and welcome to BYC.
Could you post a few more pictures of her eye? Up-close, and in good-lighting?
Face edema (swelling around the face) in several birds could indicate a respiratory infection. There are several that affect poultry, but you're most likely to see Infectious bronchitis, Coryza, or MG (mycoplasma gallisectum). There are often other symptoms with respiratory diseases such as nasal discharge, sneezing, rattled breathing, sometimes plaque deposits in the mouth. Have you seen any of that along with the swelling?
If you would like to know which respiratory disease if/you're dealing with you can send a swab into your state veterinary lab, or a national one like Zoologix.
Here are some links,
Testing.
https://www.zoologix.com/avian/Datasheets/PoultryRespiratoryPanel.htm
https://www.metzerfarms.com/PoultryLabs.cfm
https://www.aphis.usda.gov/animal_health/nahln/downloads/all_nahln_lab_list.pdf
MG
https://extension.umd.edu/sites/ext... Mycoplasma gallisepticum (MG) Infecti....pdf
https://www.merckvetmanual.com/poultry/mycoplasmosis/mycoplasma-gallisepticum-infection-in-poultry
Coryza
https://thepoultrysite.com/disease-guide/infectious-coryza
https://www.merckvetmanual.com/poultry/infectious-coryza/overview-of-infectious-coryza-in-chickens
Glad you joined.
