For citation:
Franus D. V. Thickness Influence of the Multylayer Corneal Shell on the Value of Intraocular Pressure. Izvestiya of Saratov University. Mathematics. Mechanics. Informatics, 2017, vol. 17, iss. 2, pp. 209-218. DOI: 10.18500/1816-9791-2017-17-2-209-218, EDN: ZEVXBZ
Thickness Influence of the Multylayer Corneal Shell on the Value of Intraocular Pressure
A research of changes in the stress-strain state of the corneoscleral shell of the human eye under loading by a flat base stamp is made. In this paper a three-dimentional finite-element model of contact problem under loading of multilayer corneal shell with flat base stamp is presented. This mathematical model is made in software package ANSYS. Cornea is modeled as a transversely isotropic spherical shell of variable thickness composed of four layers: epithelium, Bowman's membrane, stroma of the cornea, and Descement's membrane. Moreover, all layers have individual elastic properties, which are significantly different in tangential direction and in thickness direction. Detailed description of the contact interaction of the corneal shell and flat stamp is presented. Since the thickness of the corneal shell changes in the center, the attached flat stamp deforms the corneal shell in different ways. The paper describes the numerical calculation of the diameter of the contact zone between the shell and the stamp, on the basis of which it is judged in clinical practice about the value of intraocular pressure. Values of correction coefficients of intraocular pressure are obtained depending on the thickness of the corneal shell in its center.
1. Avetisov E. S. Blizorukost’ [Myopia]. Мoscow, Meditsina Publ., 1999. 285 p. (in Russian). 2. Choplin N. T., Lundy D. S. Atlas of Glaucoma. Moscow, Logosfera, 2011. 372 p. (in Russian). 3. Vit V. V. Stroenie zritel’noi sistemy cheloveka [The structure of the human visual system]. Odessa, Astroprint, 2003. 664 p. (in Russian). 4. Zakharov V. D. Vitreoretinal’naia khirurgiia [Vitreoretinal surgery]. Moscow, Moskva Publ., 2003. 173 p. (in Russian). 5. Iomdina E. N. Mechanical properties of the human eye tissues. Modern Problems of Biomechanics, Moscow, Moscow Univ. Press, 2006, vol. 11, pp. 184–201 (in Russian). 6. Rodionova V. A., Titaev B. F., Chernykh K. F. Prikladnaia teoriia anizotropnykh plastin i obolochek [Applied theory of anisotropic plates and shells]. St. Petrsburg, St. Petrsburg Univ. Press, 1996. 278 p. (in Russian). 7. Nesterov A. P., Vurgaft. M. B. Kalibrovochnye tablitsy dlia elastonometra Filatova—Kalfa [Calibration tables for elastomer Filatov–Kalfa]. Vestn. oftal’mol. [Bulletin of ophthalmol ogy], 1972, no. 2, pp. 20–25 (in Russian). 8. Franus D. V. Finite-element model of intraocular pressure measurement by Maklakov ap- planation tonometer. Proc. VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016), 2016, vol. 4, pp. 6631–6636. 9. Shevchenko M. V., Bratko O. V. Evaluation of biomechanical peculiarities of fibrous eye layer in myopia and glaucoma. RMJ Clinical Ophthalmology, 2011, vol. 12, no. 4, pp. 124–125 (in Russian). 10. Avetisov E. S., Bubnova I. A. Issledovanie biomekhanicheskikh svoistv rogovitsy in vivo [Reseach of biomechanical properties of cornea in vivo]. Biomekhanika glaza–2007 : Sb. tr. konf. [Biomechanics of the eye : Coll. of conf. works]. Мoscow, State Research Institute of Eye Diseases of Russian Academy of Medical Sciences Publ., 2007, pp. 76–80 (in Russian). 11. Avetisov E. S. Diagnosticheskie vozmozhnosti elastotonometrii [Diagnostic possibilities of elastotonometry]. Glaukoma: Real’nost’ perspektivy: sb. nauchn. st. [Glaucoma: Reality, prospects: Sat. sci. article]. Мoscow, State Research Institute of Eye Diseases of Russian Academy of Medical Sciences Publ., 2008, pp. 81–85 (in Russian).
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