Steve G.
Yes, I have these things too. It starts as a very small blind spot near the center of my vision and then gradually expands in a circular fashion with the zig-zag lightning bolts at the outer edge of the circle. The circle finally expands past the edge of vision and then the episode is over. A little bit of nausea is associated with the attack that usually lasts about 30 minutes. I just had an episode and found your query on the web. From what I've read so far, it is a good idea to get an MRI. Best wishes.