Here is how I treat eye infections in chickens.
I prepare a strong tea: for 1 tea spoon of black tea leaves – 1/2 cup of boiling water. Let the tea to stay for 1/2 an hour and cool down. Then gently wash the sick eye with tea using a cotton swab, wiping out any discharge with a paper napkin. I do this twice a day, in the morning and at the evening.
One hour after the tea I put some petroleum gelly on the closed eye to prevent clogging with dry mucus.
I continue with the tea for 1 week, then stop the tea and use the gelly only. At night it’s OK to put the gelly after the chicken is asleep. Just wake her up gently, carefully open eyelids wipe out any discharge and gently put the gelly on the closed eye.
I noticed that younger chicks with eye infections retard in growth. They catch up later. A slight sign below the eye will remain.