“…The age-related periodization of human development adopted at the VIIth conference with the problems of agerelated morphology, physiology and biochemistry (1965) is used. As the load on the visual apparatus begins to increase from about 4 years, our study included persons belonging to the following age groups: first childhood (girls and boys aged 4-7 years), second childhood (girls aged 8-11 years and boys aged 8-12 years), adolescence (girls aged [12][13][14][15]…”