Ok to fly with burst blood vessel in my eye?

Yes: A broken blood vessel on the surface of the eye is called a subconjuctival hemorrhage. It is the equivalent of a bruise elsewhere on the body. A new subconjuctival hemorrhage can rebleed in the first week, but there is no contraindication of flying in a pressurized cabin.

Depends: In your question, you did not indicate where the burst blood vessel is located. If it is in the conjunctiva (giving a red spot on the white part of your eye - called subconjunctival hemorrhage), then flying is fine. If it is in the retina or elsewhere, then maybe not depending on the cause.