Well. That's certainly a wealth of information to go on.
If the hen is walking and drinking and otherwise behaving normally while keeping both eyes shut, it could mean she has a painful eye issue. Bacterial infection or pink eye can cause pain in the eyes. Flush with eye wash or a saline solution. Then place an ophthalmic antibiotic ointment in each eye twice a day.
If the hen is mostly lethargic and standing around doing nothing with eyes closed, she's got something far more serious going on.
Call your feed stores and ask if they have terramycin antibiotic eye ointment. She probably has a bacterial infection, and the closed eyes signal her eyes are causing her pain.