[Slight variations of vitamin A in blood levels and their effect on visual perception]

The purpose of this study was to find out a simple perceptual visual test that gives the possibility to detect the visual incidence of slight variations of the vitamin A blood rate. The visual function was tested in 30 young subjects without refraction problems at the same time as blood concentration of vitamin A was measured. Visual tests comprised visual acuity at high and low luminance level, contrast sensitivity, glare sensitivity as well as attenuation characteristics of the eye toward flickering stimuli. Among all these tests, only the flicker test showed some relation with the plasma vitamin A levels, which were situated between 35 and 75 mcg/100 ml.