Boychild and I both have these...no headache, just the colors. Hubby...never. Go figure. It starts as a pulsating dot in the corner of my eye, then spreads into an expanding rainbow around the outer peripheral, usually the right, sometimes the left. Son, too. My brother made glasses for years, took some classes in optometry and he always called them optical migraines.
Scary when you're driving but now I just shut my eyes and enjoy.