M.P.
I get them a few times a year. I asked my opthamologist but I can't remember what he said. I do know that it wasn't anything alarming though. I do not get headaches but get a weird visual feeling and then my peripheral vision goes fuzzy and I can't see well. It's rather hard to explain if you haven't had one before, but the "sparkly arc" comes close. They usually last between 20 and 30 minutes.