It is talking about visual snow when the eyes are open. I have this condition and I can tell you it is very noticeable. Also migraine and tinnitus. However, it is quite distinct from migraine's visual aura which looks like a reflection or a light corona and tends to go away after a few moments, whereas visual snow is visible 24/7 and looks exactly like the images in the wikipedia article suggest.
I think floaters and such in the eye are more common also in the general population as a temporary phenomenon.