The visual "snow" is from low intraocular pressure (the opposite of glaucoma). I see it as blue and green sparkles that were strongly enhanced when I used cannabis (known to decrease eye pressure and combat glaucoma). In my case it probably comes from no longer playing a wind instrument (oddly, playing such instruments is known to increase eye pressure). My vision was perfect until some years into playing. My eyes compensated during a decade and a half of playing, so when I stopped, my eye pressure decreased. It also had the effect of curing my nearsightedness, as the lower pressure allowed my eyes to change shape and regain focus. My resulting 20:15 vision (better than 20:20) just comes at the cost of the sparkles, which are not at all distracting. It's not unlike ringing of the ears--you forget until something calls attention to it.

I also get after images, but I've always put that down as permanent changes to my visual cortex from chronic (but former) cannabis use. Cannabis actually increases the flow of sensory data to the brain (why music sounds more detailed, food tastes better, colors are enhanced, etc.). My cerebral cortex has adapted to the increased sensory input.

If, like me, you see walls breathing, the reason is because the permanent changes to my visual cortex allow me to perceive objects in greater detail. The cerebral cortex interprets this as an object being closer (how you normally increase detail in vision), so the center of my vision seems closer than the periphery. As my eyes move, it makes it seem like things get closer and farther away (why the walls seem to breathe). This is most noticeable with objects that have little detail to begin with (white walls in particular) This is also why too much cannabis makes people think they are zooming into objects. The changes to my visual cortex also allow me to perceive the motion of a minute hand or the movement of the sun (by watching shadows move).

TLDR:I'll bet you've used a lot of cannabis.