pulsation phenomenon
   The term pulsation phenomenon is indebted to the Latin verb pulsare, which means to hit, to knock, to pulsate. It is used to denote the repeated "magnification or "minification of visually perceived objects. The pulsation phenomenon has been described as a special quality of "macropsia and " micropsia occurring in the context of " migraine aura. The cycle of pulsation (i.e. from the onset of the object's apparent increase or decrease in size until the return to its proper size) tends to be of the order of 10 s. When macrop-tic or microptic vision sets in more gradually, it is referred to as " zoom vision. The pulsation phenomenon has also been described in relation to a recurrent dimness of vision. In the latter case, visually perceived stimuli are gradually replaced by a uniform greyness, to then reappear at a faster pace.
   References
   Klee, A., Willanger, R. (1966). Disturbances of visual perception in migraine. Acta Neurolog-ica Scandinavica, 42, 400-414.

Dictionary of Hallucinations. . 2010.

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