One of my chickens eyes are red and watery with a fresh "cut"

I would check her for signs of a respiratory disease just in case. Mycoplasma can cause eye bubbles, but so can injuries and infections. Her eye need to be cleaned with some saline or eye wash, then Terramycin or Neosporin Ointment can be applied to the eye inside and outside twice a day. Most of the time rats are after feed in the coop, but if they are meat eaters, then you meed to work on getting rid of them around the coop. I use Just One Bite in locking bait boxes outside of my coop, and they have pretty much gotten rid of those pests.