Flicker Fusion Frequency: Background and Applications

Abstract

The rate of successive light flashes from a stationary light source at which the sensation of flicker disappears is now being used as a diagnostic test in physiological stress and certain medical conditions. The purposes of this review are: "(a) to give an introductory summary of information concerning the fundamental variables; (b) to discuss variations in testing procedures and techniques, as a background for comparison of results obtained in various laboratories and for suggestions of standarization of the method; and (c) to present the main results obtained in studies on various stresses, with a discussion of the physiological and clinical problems involved." The stresses considered are anoxia, hyperventilation, effect of CO2 inhalation, acceleration, cold hip baths, nutritional stresses, visual fatigue, fatigue in sedentary work and in physical exertion, sleep deprivation, drugs. The clinical conditions considered are anemia, emphysema, cardiovascular disease, metabolic disease, cerebral lesions, brain tumors, psychoses, eye disease. "One important result of the application of the FFF in physiological stress and pathological conditions is the strengthening of the view that the critical location of this function is in the CNS rather than in the retina. As an approach to the study of CNS excitability the measurement of the FFF has a wide field of potentially useful application.