The Scintillating Scotoma

Have you ever wondered whether you'll go blind or deaf first?

I'm pretty sure that I know that I'll go blind in my dotage, rather than deaf. And the reason is that I experience a thing called scintillating scotomas.

Basically, this is a distortion in my visual field. It appears, grows, moves slowly and goes away after maybe ten to twenty minutes. It's hard to describe exactly what it looks like, though I've described it as "wrigglies". It's not like the "floaters" that people sometimes experience - those are actual protein fragments in the eyeball, whereas my scotomas are still visible when I close my eyes. Wikipedia has a couple of artists' impressions of what it looks like, but none of them really reflect what I see. This is perhaps the closest:


"Scintillating scotoma" by Mikael Häggström.

Even this isn't really accurate, since the background image still shows distinctly through the distortion. When I experience it, it really does disrupt what I can see.

They become a problem when they cover the main part of my visual field. When this happens I can't really see anything properly - though it's because my vision is distorted rather than just seeing blackness. More often I can keep doing whatever I'm doing because the scotoma doesn't cover the primary area of visual acuity - it covers my peripheral vision, but not my central. In fact, you probably wouldn't even realise that I'm experiencing one if you were watching my behaviour at the time. Sometimes it covers just part of my central vision, and I have to look slightly sideways at things in order to see them properly.

Scintillating scotomas are usually associated with migraines - and when I was young, they were a sure sign of the onset of a headache. However, my headaches were never particularly serious, and these days I get the scotoma without a headache at all.

So far I've been lucky enough to not have it occur when I'm driving. However, the onset is gradual enough that I would certainly have time to pull over and stop if it did happen.

There's really no reason to think that it'll get worse as I get older. I just posted that as a hook to get you interested.