[Visual fatigue during work associated with increased visual loading]

Visual perception is an important factor of human activity. The quality of production activity of the worker depends on its accuracy and speed. Representative groups of workers with various occupational activities, associated with considerable loading of visual system, were systematically examined by clinical and functional methods in the course of several years. A total of 765 subjects were examined, aged from 20 to 55 and a length of service from I to 25 years. The results reveal considerable alterations in visual system within one working day. The most general features of those alterations are as follows: elevation of the threshold of electric sensitivity towards the end of the working day, reduction of light-distinguishing and colour distinguishing sensitivity, the closest point of clear vision is removed father, unproper ergogram with an ascending course, reduction of fusion ability towards the end of the working day, etc. A great part of the subjects over the age of 40, were established to have uncorrected presbyopia, leading to high strain of accommodation and convergation, followed by visual fatigue. The adaptation of visual system to labour conditions is the best at the age range 25-35. The alterations in the visual function are far better manifested in the age group over 40. The determination of fatigue degree and the time of developing of the first alterations is of particular significance for the introduction of additional rest for rehabilitation.