I believe I got it from weed. I was a daily pot smoker for about 2 years. During that time span, I used LSD once, mushrooms 3 times, and smoked salvia a couple of times.
The night I acquired HPPD, I took a Zoloft thinking it was similar to benzodiazapenes, then I smoked marijuana. When I was trying to fall asleep, I noticed closed eye visuals for the first time, and then when I opened my eyes I saw visual snow everywhere.