HPPD is an EXTREMELY rare condition. Seeing textures move is perfectly normal. Sight is a subjective thing. If you're in bed and you see yellow shapes moving with your eyes closed, it's all your imagination and because you're entering other states of conciousness. Trails are also common, we have just experienced full-blown psychedelic trails, so we know what they are in a psychedelic point of view. So we can give it a name.
HPPD basically only occurs when one takes huge amounts of a psychedelic drug, usually the person has a frightening life changing trip and is sensitive to the drug. The second option is one has abused a psychedelic drug. HPPD virtually always goes with dissociative thinking, fear disorder and depression. If you fit the criteria, you might have HPPD. If not, you're not having HPPD and it's just placebo/imaginary thinking.
Sorry if I sound harsh, but HPPD is so rare, I find it hard to believe so many people claim to suffer from it.