When I was child I saw visual snow only when I wanted to see it and it was not in full field of vision, i saw it only as figures that I imagine in my head. My hypnotist doctor told me that I have a very high power of self-confidence(hope I wrote it right).
Much before I got T, I noticided that my VS "spilled" to all my field of vision after smoking or PTSD.
In my opinion all the things that I write in a pool may be related to each other and to tinnitus that caused by drugs using, so if some one who already have VS (for example) and still not have tinnitus had to avoid using psychiatric or street drugs in any way possible. In my opinion, the best way to deal with stress is visit a good psychologist.
Hope for the sufferers, I suffered from also two things that I mentioned in the pool, of the one of them I recovered through stress control (without drugs helping) and willpower, of the second through prayer+fast and after full physical exertion.