I still remember when that happened to me, it was quite a bizarre experience. It started after coming back from a meeting where the room was all painted white and had some of the brightest light I had seen and then it started while I was coming back home in the car, it was a sunny winter day with bright white reflected snow.

I didn't feel the pain of a migraine like I usually do but the zigzag pattern started as a very small point in the middle of my vision, got home, lay down on the couch and the circle grew and grew. I'd say around two third of the outline of that circle was a zigzag and I vividly remember that there was a checkboard pattern around the part that wasn't zigzag.

It was hard to see at some point as it became bigger and bigger and I was beginning to panic. But there was an inner circle inside of it of clear vision and once the zigzag circle became so big that it was outside of my vision, I was back to normal vision.

I did some research back then to figure out what happened and saw all those medieval paintings and drawings that people with similar experience did. I would enjoy the experience much more today with that knowledge but it never happened again.

The experience last between 30-60 min.