On the way to work he experienced something he’ve worried about for a long time - a visual migraine while he was driving. For those who don’t know, he occasionally get migraines, and lately (the past few years) they have either been accompanied by or have solely consisted of what is known as a “visual migraine.” This is a result of blood vessels in the visual part of the brain suddenly spasming, causing bloodflow changes in the region and, hence, visual weirdities. He was most concerned about this because it does impair his vision and, when on the road, this could be a serious problem.
Stuck in the middle of heavy traffic this morning, he suddenly saw the tell-tale flickering, like a non-existent light flashing on and off quickly right in the center of his vision. Within a few minutes it expanded and grew to encircle his vision, leaving a disorienting open area in the middle of his vision while blurring out the lower right. Too far from home to turn around, he decided to press on, doing his best to pay very close attention to what was going on around him.
For years he’ve attempted to describe the sensation, but it’s almost impossible to really get across how disorienting it is. Today, however, he finally figured out a good way to do so: Below you’ll see a pretty accurate animation of what happens. The timeline is obviously shortened, so imagine this happening over a half-hour time span. This is very similar, but still not quite as strange as what he see in his head (nothing is happening in his eyes - this is all deep in the brain.