I want to clarify your question better. Where exactly is the cyst? Is it on the eyelid? Is it on the white of the eye? Can she see out of the eye?
I have actually seen many of these. They are probably epithelial inclusion cysts. I have removed a few; and they actually come out pretty easily. Most are encapsulated and come out as a whole. I always get a CT first to make sure whether it is free or attached to the bone, etc. There would be no harm to the eye. As far as cancer, most are merely inclusion cyst; but the only way to know for sure is to remove it. They do have a tendency to grow with the child.
Hope this helps and thank you.