My Husband Passed Out And Hit His Head While Prepping

My husband passed out and hit his head while prepping for a colonoscopy. Pretty bad black eye from it. Dr. xrayed eye and neck and all was fine. That has been 2 weeks ago. He is healing well. But tonight, he started to see flashes of light around the eye that was previously black, but only when he moves his head. Is this normal when healing from a black eye type thing?