Tonight when i was putting my chickens away for the night, i noticed one of my hens had bubbles on the bottom part of both her eyes. She is one of the younger ones we have, she was hatched in October 2012. She still runs around and is eating. She isn't coughing or sneezing and her breathing sounds fine. It is just her eyes that are watery and the bottom is lined with bubbles. And she isn't acting at all out of the ordinary, just her eyes. She does seem to be able to see. There are no other hens that have this happening. They all seem fine. Please help! Any idea what caused this and what i can do to treat it?