- Also known as photome, phosphorescence of the retina, scintillations, and suffusio scintillans. The term photopsia comes from the Greek words photizein (to give light, to illuminate) and opsis (seeing). It is used to denote a group of * simple or * geometric visual hallucinations such as * phosphenes, luminous rays, coruscations, heat waves, * snow lights, and * Moore's lightning streaks. In ordinary parlance, these phenomena are referred to as light flashes. Simple forms of photopsia are designated as * unstructured pho-topsia, while the geometric forms are designated as * structured photopsia. Sometimes photopsia may lead the affected individual to perceive fleeting illusory images or * passage hallucinations. It has been speculated that photopsia may even act as a * point de repère for the development of * complex visual hallucinations. As the British surgeon Walter Cooper Dendy (1794-1871) wrote in 1847, "The brilliant beams in the suffusio scin-tillans, so varied and so whimsical, might be readily moulded into human form by the imagination of an enthusiast or the feelings of the ghost-seer, who is usually morose and melancholy, in a state of longing for a ghost or a mystery." Photopsia may be classified as a subclass of the *positive spontaneous visual phenomenon (PSVP). When attributable to intraocular pathology, it may be classified as an *entoptic phenomenon. Pathophysiologically, photopsia is associated primarily with aberrant neuronal discharges in any part of the visual system. Eti-ologically, it is associated with such diverse conditions as posterior vitreous detachment (PVD), retinal break, acute zonal occult outer retinopathy, retinal migraine, migraine with aura, *migraine aura without headache, metastatic tumours, occipital epilepsy, cocaine intoxication, *hallucinogen-induced persistent perception disorder (HPPD), and *digitalis intoxication. Historically, the term photopsia is used in opposition to the term * morphopsia, the latter term referring in a broad sense to *formed visual hallucinations.ReferencesAmos, J.F. (1999). Differential diagnosis of common etiologies of photopsia. Journal of the American Optometric Association, 70, 485504.Dendy, W.C. (1847). The philosophy of mystery. New York, NY: Harper & Brothers.Klee, A., Willanger, R. (1966). Disturbances of visual perception in migraine. Acta Neurolog-ica Scandinavica, 42, 400-414.Oishi, A., Miyamoto, K., Kashii, S., Yoshimura, N. (2006). Photopsia as a manifestation ofdig-italis toxicity. Canadian Journal of Ophthalmology, 41, 603-604.
Dictionary of Hallucinations. J.D. Blom. 2010.