Whenever a friend of mine takes acid, he gets visuals for a week or more afterward. Not full on intense visuals, but every couple of days he'll notice after images, tracers, colour distortions or the like. He beleives his brain may be more susceptible to HPPD than others, so severely moderates his use with acid or mushies, cause what he's heard about full blown HPPD is not very nice. He wonders if he will have to moderate as severely with DMT.