What cause my vision to black out?

[Tayop01]

What can be the cause of my vision black out? My vision blacks out for a split second like 5 times after having a nose bleed at 4am when i was sleeping. This not my first time this happen and when i went to go see the optometrist ( other eye problem too) they just said i had astigmatism, nothing serious. I also have anxiety if that help and really havent had any good sleep for the past 3 days due to allgery. I havent experience any other symptoms beside just sleepyness and im only 16 years old.

[John C Hagan III, MD, FACS, FAAO]

First of all you need to share this information with your parents.  Astigmatism would not cause those symptoms. I would suggest you see an Eye MD ophthalmologist to evaluate your complaint of your vision "blacking out"   At your age serious causes are fortunately rare but you do need to have a physician, not an optometrist, evaluate your complaints.