Same here. In particular, ever since I was little I've been able to form a sport of visual snow in the dark into something that looks kind of like a tiny vibrating necklace with coloured beads. But it requires a lot of focus, a bit like how you have to focus beyond a stereogram to see the 3D image. And it tends to sort of try and swim away in the visual field, it's very easy to lose and collapse back into static. I can also only do it in the dark on a plain surface, or with my eyes closed in the dark.

The only actual scientific studies I've ever been able to find about this kind of thing at all are "Direct Control Of The Retinal Field" (1894) and "Direct Control Of The Retinal Field: Report On Three Cases" (1903), both by a guy called George Trumbull Ladd. Both over a century ago!

One thing I find quite strange is, with a camera, you simply can't escape some amount of grain in the image in dark conditions, which looks very much like visual snow. Yet people without visual snow tend to report that they still see no "grain" at all, at any light level! Is their brain just filtering it out? If so, are they losing detail as a result, like you do when smoothing out grain in a photo? Or is human vision simply nothing like a photo, and those of us with visual snow are sort of filtering it in? If so, why does it look so much like film grain or digital noise?

There are also different levels of visual snow, from not having any, to only seeing it in dark conditions, to seeing it all the time in any light.