That is strange. I would get her to the vet for an exam, especially have the eyes checked.
See what the vet has to say. If she thinks nothing is wrong & has no explanation you should seek the help of a behaviorist.

If this is a problem that just started it may get worse & sooner than you think. I don't want to scare you but do want you to resolve it before it does get worse.

I wish you the best of luck!