Scintillating scotoma

For today's post I decided to tell about a weird thing that has happened four times now. The last episode was day before last.
Two or three years ago when it happened the first time, I pretty much dismissed it.
The second time, I googled the symptoms and learned it is called scintillating scotoma. The first three times were the same, starting with moving, flashing zigzagged arcs on the left side of my field of vision. During thirty minutes or so, they get worse - larger, colorful and more filled with motion. They can obscure your vision pretty bad. You feel the need to lie down and shut your eyes. But then you find out the moving lights and lines are not in your eyes but in your brain. No matter how dark you make your surroundings, they persist. But after an hour, you are back to normal and can resume whatever you were doing.
On Monday the episode started with a small, bright wiggly polygon in my lower right field of vision. The one shape turned into many, and they grew bigger than the zigzags did covering a larger area. I lay down and was fortunate enough to sleep for a few minutes. When I woke up, they were gone.
I don't get a headache or have any other symptoms. I think the "jury is still out" as to the causes. For me, I wonder if it is triggered by bright light, because I was really aware of light right before the visual show started.
I just thought I would share in case someone else out there had them.