Where are you located? Are there mosquitoes out now or recently? Can you try to look into her eyelids to see if her eye is intact? You can use saline or water to clean her eye. Then apply either Terramycin eye ointment if you can get it at your feed store, or plain Neosporin or Triple Antibiotic Ointment 2-3 times daily. Pecking or her eyelid by others, scratching herself might be possible, and she could have fowl pox, although it looks more like peck wounds. Does she have any sneezing, crackles or wheezes, or nasal drainage? Those would be signs of a respiratory disease, such as MG or coryza, which also can cause the eyelid swelling. If she doesn’t have those other symptoms, it might just be from peck wounds. Here is tylosin (tylan) powder to put in the water, 1 tsp per gallon for 3-5 days:
https://www.jedds.com/shop/tylan-soluble-100-g/