It's not an abscess, she has an infection or a virus, or she may have injured the eye. There are lots of things that can manifest themselves as swollen eyes in chickens. Separate her from your other chickens..put her in a dog crate or rabbit cage or anything where she will have some privacy but still can hear and see her friends. It's also necessary in case what she has is contagious to other chickens. Start out by doing the simple things first..wash the eye twice a day with saline or human eye wash..you can warm the bottle in hot water til the contents are body temperature, then just drip it in her eye and she won't feel it. Follow that with a careful dab of Triple Antibiotic ointment around the eye, using your clean finger tip or a q tip. Make sure the ointment does not have pain killer in it. It will seep into her eye. Do this twice a day too. Get some poultry vitamins from the feed store and give them to her and the whole flock in the drinking water. Make sure that she continues to eat and drink well. If you don't see improvement in a day or two, or if she shows other symptoms like nasal discharge, sneezing, coughing, poor appetite, it's likely she will need antibiotics. A vet is best, and even if they don't treat birds some will give you a prescription for antibiotics that you can get filled at a veterinary pharmacy or on line. If a vet is not going to work for you, you can look for water soluble antibiotics like Oxytet on line, or use injectible antibiotics like Duramycin or Tylan that you can get at the feed store. If you do have to resort to antibiotics let us know and someone can tell you what and how much to use. It is important that you monitor her and the whole flock pretty closely, because chickens conceal symptoms until they are unable to. On the other hand, sometimes all you need is just the eye wash and antibiotic gel.. and it will clear up with no problems. Keep us posted on how she is doing! Also obviously, antibiotics won't work for a virus, but they will help combat secondary infections if she does have a virus, and that's always my first go to in situations like yours . I doubt it's avian influenza, but I suppose there's always that possibility. If it's Coryza it will respond to antibiotics. You can treat the whole flock if others start getting sick, but that might never happen.