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Medical Term:

phi phenomenon


an illusion of movement, which occurs by means of successive visual impressions at intervals of 115 to 120 sec; when an occluder is passed from one eye to the other while a small distant light is observed, the light seems to move with the occluder in exophoria, but in an opposite direction in esophoria.

© Copyright 2017 Wolters Kluwer. All Rights Reserved. Review Date: Sep 19, 2016.