Hi Tiberia and welcome to PC. One thing that hasn't been mentioned is an actual eye problem being the cause. The reason I mention this is it happened to me 2 yrs ago. When I look to the side, it was like a lightening flash....so I went to see my eye doctor. Often this is just Posterior Vitreous Detachment - some of the gel like structure shrinks slightly with age and this causes the flash. Other times it can be more serious like a detached Retina. Yes it can also be light symptoms of a migraine. If you still are getting these flashes its most likely your eye and you need to get an eye exam. I was also concerned because I never heard of this before. Hopefully this will get better. Here's a link explaining light flashes in the eye:

http://www.livestrong.com/article/10...t-flashes-eye/