No abstract

Introduction. According to the World Health Organization (WHO), glaucoma accounts for 4-5% of the total ocular pathology, making it one of the most common eye diseases in the world. The first sign of the disease is a constant or periodic increase in intraocular pressure, which leads to the development of visual field defects, optic nerve atrophy, and dystrophic changes in eye tissues. Detection of glaucoma and ocular hypertension is done by measuring the intraocular pressure, which is the standard procedure for diagnosis of the condition of eyes in all patients over 40 years of age. Patients with a diagnosis of "glaucoma" should constantly measure the intraocular pressure, which is necessary to control the effectiveness of treatment, its correction and evaluation of the effectiveness of drugs. The purpose of the article is to develop the system for assessing the intraocular pressure level using the interference pictures parameters observed on the eye cornea in the polarized light.

Background: Near visual work causes redistribution of internal stresses in the cornea, leading to a change in the shape and parameters of the interference patterns observed on the cornea in polarized light. Purpose: To assess the effect of various types of visual load on the extraocular muscles (EOM) in children and adolescents on the basis of characteristics of the interference patterns observed on the cornea in polarized light. Material and Methods:The interference patterns observed on the cornea in polarized light were studied in children and adolescents before and after they performed a visual load task which consisted in either working with texts printed on paper at different parameters of convenience for reading (97 individuals) or playing Tetris on a smartphone (58 adolescents). A symmetry coefficient K was calculated for the quantitative assessment of changes in interference pattern parameters induced by visual load. Results: Performing a visual load task which consisted in working with texts printed on paper resulted in a significant increase in asymmetry between the actions of the EOM in 60% to 73% of children; this was indicated by the values of a symmetry coefficient K which were twofold to six-fold higher than normal. Performing a visual load task which consisted in playing Tetris on a smartphone resulted in an increase in asymmetry between the actions of the EOM in 64% of adolescents. Conclusion:Our research confirmed that studies on the stress-strain behavior of the cornea in polarized light are promising for assessing the effect of various types of visual load on the function of EOM.

The parameters of interference patterns observed on the cornea in a polarized light in pathology of extraocular muscles were quantitatively evaluated. A study of the shape of 147 interference patterns observed on the cornea in a polarized light showed that the horizontal deviation of an eye in 56 % of cases was caused by the displacement of the attachment of the upper rectus muscle towards the inner rectus muscle. During illumination of the cornea of a live eye with polarized light, a specific interference pattern in the form of a rhombus formed by rainbow stripes (isochromes) is observed. It is established that such an interference pattern is the result of the influence of extraocular muscles on the cornea. The findings showed that the weakening of the force of one of muscles leads to asymmetric distortion of the shape of the interference rhombus, which is manifested with a reduced length of the corresponding section of the diagonal. On the contrary, as the force of the muscle increases, the corresponding section of the diagonal enhances. The displacement of the attachment site of direct extraocular muscle along the line of action is equivalent to a change in effort on its part, indicated appropriately by the shape of the interference rhombus. As the muscle moves away from the line of action, the angle of the interference rhombus is shifted away from the corresponding meridian. Key words: polarized light, optical anisotropy, cornea, extra−ocular muscles, interference picture.