Can prolonged neural adaptation lead to HPPD?
No.  This disorder requires the sufferer to have used hallucinogenic substances in the past:


  Previous use of hallucinogens by the person is necessary, but not sufficient, for diagnosis of HPPD. For an individual to be diagnosed with HPPD, the symptoms cannot be due to another medical condition. 


from Wikipedia following the DSM-IV criteria reproduced here.


  A. The reexperiencing, following cessation of use of a hallucinogen, of one or more of the perceptual symptoms that were experienced while intoxicated with the hallucinogen (e.g., geometric hallucinations, false perceptions of movement in the peripheral visual fields, flashes of color, intensified colors, trails of images of moving objects, positive afterimages, halos around objects, macropsia, and micropsia).