I feel there is no problem like visual snow and this is coined online by few people.
Even cases where people are unable to read, write or see (extreme condition) are undergoing vitreous detachment that is why problem in vision. In other cases where people have any neuro symptom present it would be HPPD, MS etc.
Rest of the cases with visibility in almost all conditions might be experiencing normal entopic phenomenon!
One should not generalize cases. The term visual snow does not exist at all.