The term imagistic phosphene comes from the Latin noun imago (image) and the Greek words phos (light) and phainein (to shine). It is used to denote a "phosphene (i.e. a flash of light) presenting in the shape of a " formed hallucination. Etiologically, imagistic phosphenes are associated with a variety of conditions, including migraine with " aura, " migraine aura without headache, the use of "hallucinogens, "flashback phenomena, and " hallucinogen-induced persistent perception disorder (HPPD). It has been suggested that phosphenes occurring in the context of a migraine aura always start out as simple visual phenomena, and sometimes develop into geometric patterns, while the third stage of imagistic phosphenes (i.e. formed hallucinations) is seldom attained. At any rate, imagistic phosphenes are considered extremely rare phenomena.
References
Sacks, O. (1992). Migraine. Revised and expanded. New York, NY: Vintage Books. Selby, G., Lance, J.W. (1960). Observations on 500 cases of migraine and allied vascular headache. Journal of Neurology, Neurosurgery and Psychiatry, 23, 23-32.
Dictionary of Hallucinations. J.D. Blom. 2010.