Negative afterimages

[wisp]

Icosa,
I'm not familiar with HPPD, will you talk more about this? It sounds interesting.

The only negative images I recalled in dreams is when there is an xray being taken of a body part. This has happened twice for me.

[Icosa]

Hello Wisp,
Light enters the eye and produces chemical changes in the retina.  Prolonged stimulation by a bright image desensitizes part of the retina, so that it does not process new input as well as the rest of the retina.  The desensitized area appears as a negative afterimage, which lasts 30 seconds or so.  When such an "illusion" persists, it is considered a disorder by the American Psychiatric Association!  The diagnostic criteria is defined here-http://hppdonline.com/diagnostic.php.  
I thought it was rather interesting that my lucid dream had enough substance, in this case, light, that it produced chemical changes in my retina to the point that when I went immediately to an awake state, I was seeing afterimages of my dream!
I guess that anything that can't be rationally explained, somehow becomes a disorder.  That is something, of course, that I don't agree with.  But then again, maybe someday, science will walk down that road and take a closer look at what this phenomena really consists of.

[Icosa]

Greetings all,

After having to quickly exit a lucid dream state directly to an awake state, I experienced negative afterimages of the dream environment.  I thought this was interesting, and did a little research on the phenomena.  Prolonged stimulation by a bright image, such as a light source, desensitizes part of the retina, which retains the image that appears as the negative afterimage.  I thought, could this be a way to prove the 'physical' validity of the lucid or of any dream state?  Further investigation shows that experiencing afterimages is also indicative of something called HPPD, or Hallucinogen Persisting Perception Disorder, a visual disorder with psychological implications!  Frankly, all I did was wake up, so I discounted that diagnosis as definitely not applying to myself!
Anyone with a similar experience?