Here's an artist's depiction. In my experience, the ring expands slowly outward from the center, and it is composed of zigzag patterns that move around the ring, rather than little colored bubbles, as is indicated here. The aura creates a blind spot in the area of the shimmering ring. At the Wikipedia page on the subject, there are some animated gifs that people have created to simulate the effect.
Whenever I get one, I refer to it as the "Mystic Donut."
Here's another animated simulation (Thanks, Derek).
For me the effect is most often triggered by a cup of coffee and a sudden exposure to bright light. The phenomenon is caused by a spreading wave of neural firing called a cortical spreading depression in the optical cortex in the back of the brain. It doesn't happen on the retina, as in a retinal migraine, which has a monocular effect.
Unlike some other kinds of migraines, there's no pain associated with scintillating scotomas, and I find them kind of fun, as long as I'm not reading or driving.
Wikipedia on Scintillating Scotoma
I call mine the Technicolor Worm. Someone animated it here. Pretty accurate to what I see.
ReplyDeleteMine is the crystal worm and is usually accompanied by a half a day headache where nothing gets done. Very rare for me though thankfully.
ReplyDeleteIt feels oddly comforting to know that I experience the same thing as you do, James :^). I used to be scared that these were the precursors of painful headaches, but that no longer appears to be so - though I think it used to be the case. Like you, I now just go along for the ride, unless I'm driving or reading.
ReplyDeleteI get those. My optometrist calls them "scintillating migraines." Mine are painless, but distracting, but also infrequent. They most often are shaped like a football (or, rather, an eye, LOL) but sometimes a circle. I'm fascinated to see that people have actually made videos to show what they're like!
ReplyDeleteI get these too, maybe two or three times a year. They last about 20 minutes. I just sit down and enjoy the show.
ReplyDeleteGlad to know it's nothing serious!
ReplyDeleteI have these every few months. They are always shaped like a flattened C, concave side toward the center of vision, and always just on one side of the field of vision. Possibly always on the left. Ever since learning these are visual migraines (to my great relief), I've assumed they were happening in the occipital lobe, but I didn't know about retinal migraines, so I guess next time I'll cross my eyes to see what happens; if it's in the eye, I guess I'll just see one, but if it's in the brain, then two. I've never had a migraine headache, which made this all the more mysterious for many years.
ReplyDeleteThanks for this post! Your blog really fills a niche, in a big way.
This is first I've seen others discuss the same thing that I get every once in a while, too. I call it my Painless migraine test pattern. It spreads out from a spot in shimmering black and white, into a crescent that sometimes lasts 40-45 minutes. I never know what triggers it.
ReplyDeleteI feel for all of you.
ReplyDeleteI only got those rarely so far and its usually accompanied by nausea. Light becomes problematic too. A few times I spent the whole day with my head against the mattress of my bed and not moving from that spot. It was truly horrible.
Those things that you are seeing, I wonder if its part of quantum physics? :D It reminds me of those strings and squiggly rings that scientists keep on describing that are the fabric or foundation of things in existence.
I get these too, not very often though. But they only go away if I lie down and rest for a couple of hours.
ReplyDeleteMine look more like a zig zag pattern in a semi circle. I find them rather boring as you can't do anything other than wait. No reading or working, possible. At least they go away and there is no pain.
I've only had this happen to me while I was in art school, and was sleeping way too little and drinking way too much coffee. The first time was in my morning painting class, and it really threw me for a loop. I sat down in the courtyard for a hour and it went away slowly. Another weird thing that used to happen to me is called "alice in wonderland syndrome" http://en.wikipedia.org/wiki/Alice_in_Wonderland_syndrome
ReplyDeleteWhere your spatial perspective gets all out of whack for a little while.
Mine are a circle of zig-zag colours of the spectrum and gradually move out from the centre of my eye. I only have a couple a year. With no other effects
ReplyDeleteMine started 10 years ago and occurred every 6 months. Since having a brain tumor removed last year, they seem to have stopped.
ReplyDelete