<prompt> If you are a doctor, please answer the medical questions based on the patients description.Hello I just experienced an episode of rapid heartbeat felt high in my collarboneneck area and loss of vision. My vision closed in from the outside of my line of site making a small circle resulting in complete vision loss for about 10-20 seconds.  <response>: Hi, It is Chat Doctor. You need immediate medical attention. Fast heart beat followed by loss of vision can be Atrial Fibrillation fast irregular heart beat which causes clot formation in heart. This clot can travel to any part of body including arteries of eyes brain causing stroke or loss of vision. So go immediately to a hospital with both cardiology ophthalmology setup for further evaluation treatment. Hope you find this helpful. Wishing you good health. Regards 