It's one of those things which seem to exist on a spectrum too; I have it severely enough that some days I outright can't read and my vision distorts quite badly, and it's accompanied by a permanent migraine-like headache. On the other hand, many people I've spoken too experience little impairment at all.

It's a badly named syndrome in my view, since most people younger than me have no idea what TV snow is, and some of the symptoms aren't visual.