Contrast and Sensory Peculiarities of Visual System in Children of Different Age

For a normal visual perception of the world, it requires not only a high visual acuity, but also full-valued spatial-frequent channels of contrast sensitivity. These channels provide filtering of high frequencies, informing about the high frequencies of the object, and low frequencies, without which is impossible whole perception of the image even with distinction of small parts, and medium parts, especially sensitive to contrast and creating preconditions for high-quality analysis of the contours of objects. Thus, only the study of the contrast sensitivity of the visual system in all three ranges will provide complete and qualitative information. It was conducted a research of spatial contrast sensitivity among schoolchildren of three age groups (total number contained 107 people: there were 51 men and 56 women). Black-white grates with a smooth sinusoidal brightness change profile were used. The thickness of the strips is determined by their spatial frequency which is expressed by the number of black-and-white cycles per degree varies. Grates are also differed in contrast, which gradually changed from top to bottom from 0 to 1 (100%). Variation statistics methods of analysis of alternative characters parametric criteria for distinguishing medium were used for processing the results of research. An analysis of these figures allows concluding the nature of changes in contrast sensitivity by gender and age. Thus, in the group of boys a contrast sensitivity increases with age across the entire frequency range, the highest values are observed at low (0.65 cycles / degree) and medium (7.7 cycles / degree) frequencies. In middle and high groups of boys at a low frequency (0.65 cycles / degree) also have high values of contrast sensitivity. The biggest difference between the indicators of the contrast sensitivity of the right and left eyes in all age groups of boys was observed at frequencies of 5.5 cycles / degree and 20 cycles / degree, and in the middle and high groups - even at a frequency of 0.65 cycle / degree. In the group of girls retained the same patterns of contrast sensitivity change with age. It reliably increases in all frequency ranges. In the younger group, the highest values are observed at medium (5.5 and 7.7 cycles / degree) and high frequencies. At these frequencies, maximum differences in contrast sensitivity meanings of the right and left eyes are observed. In middle and high groups of girls the highest values of contrast sensitivity are observed at low (0.65 cycles / degree), medium (7.7 cycles / degree) and high (20 cycles / degree) frequencies. The maximum differences in contrast sensitivity are observed in the medium and high frequencies. A study of contrast sensitivity, that it was conducted, demonstrated that the contrast sensitivity increases at all frequencies, revealed the presence of asymmetry between the right and left eye, which reaches a maximum at frequencies of 5.5 and 20 cycles / degree. These changes indicate an increase in intensity of the information processing visual system in the area of near vision. The initial asymmetry characterizes the way of adaptation to its own structural organization. It was noted earlier in the literature that asymmetry is associated with the presence of disease, both in the peripheral and central parts of the visual system. In our research participated children and teenagers without pathology, therefore, one can consider that the presence of asymmetry may be related to the structure and functioning features of the visual system.