> For instance, when I get (got: my blood pressure is treated) migraine visual effects, I would say "lightning bolt" but thats just a textual analogue/simile. What I actually saw was more complex than that: lightning is white. My effect was polychrome.

What you describe seems to refer to scintillating scotoma, which appears to be well known and documented: https://en.wikipedia.org/wiki/Scintillating_scotoma

I personally have my doubts whether it has to do with blood pressure (i had it while on medication and normal blood pressure), or that it's generated by the brain, but lack the time/motivation/skill to research this further.