It could be a peck to the eye, some type or a symptom of respiratory illness. Flush the eye with saline to remove any debris and apply an ophthalmic ointment like Terramycin or Vetericyn eye gel.
If it doesn't get better in a day or 2 with treatment or she presents with other symptoms, then you may need antibiotics. Seeking vet care is always best.
If it's an eye ulcer from a peck, debris, etc., you'll usually be able to see it by a shining a light in the eye. If it was a few pecks and one landed in the eye and some on the face, that might explain the swelling. Like Wyorp said, Terramycin and flushing the eye will help but keep a close watch for any other symptoms in case it's something more. I had one recently with an eye ulcer and one day of saline drops and neosporin (I couldn't find my Terramycin) cleared it up.