Looks like the start of a respiratory infection. Isolate her from the other hens. If you have contact lens solution you can try to gently flush out the eye to see if the bubbles come back. At least it should sooth the eye.
If she starts sneezing, the eyes are swollen or half closed or if she sounds funny breathing (hold her up to your ear to listen to lungs) she definitely has a respiratory infection.
Get some Tylan antibiotic. Make sure you follow instructions to the letter and even if the hen(s) look better give them the medicine for the recommended number of days. It's a powder and instructions are on the back of the package. You mix with water. Terramycine drops are good for the eyes.
Watch your other hens for signs of illness. You'll probably have to treat your entire flock.