I have a burst blood vessel in back of eye (seen specialist all test back normal- perfect health) no vision left eye, how long for return of vision?

Depends on cause: If the burst vessel released blood into the back of the eye, recovery depends upon how rapidly the blood is re-absorbed which may take 1-2 months. If it is a vessel that supplies a critical portion of the vision, there may be some permanent loss. These are all modified by whether or not you have diabetes or a vascular disease like coats disease.;.