This has happened to me twice in the last 2 - 2 1/2 months, with the second one being yesterday at work. All of sudden there is like a flash, and then my vision is like I just had a flash picture taken, with the spots thing so you can't see well. The spots have a bit of prism color around them and it lasts for about a half hour then goes away. I'm pretty sure it was in my left eye, but it's hard to tell for sure. Any ideas what this could be from?