I have been getting these for many many years! Too many to count lol.
I get it in both eyes and it starts with flashing zig zags and when it goes off to the side it becomes like a ripple. I don't get headache either but a thick head. They last about 15 minutes.
Apparently it's caused by a restriction in the blood flow to the eye. It's not harmful or anything, well if it was I certainly wouldn't be here
Els
xx