The mechanical response of lamina cribrosa to the elevated intraocular pressure

Purpose To consider the different mechanical aspects of the development of glaucomatous atrophy of the optic nerve fibres. Methods The Lamina Cribrosa (LC) is modelled as a continuous anisotropic plate with radial and angular nonuniformity. The solutions for LC with different degrees of nonuniformity can help reveal the structure of the LC, for which the glaucomatous damage is most probable to develop. In the second model, LC is assumed to be of multilayer shell of revolution with elastic ties between the layers. The varying of the LC strain of the optic nerve disk after decompression surgeries due to a dissection of the sclera channel paries is analyzed. The nonlinear shell theory is used to analyze deformations of the LC. Results The calculations of the stresses and deformations in the LC show that the shear deformation of the vertical element of the LC could cause the atrophy of the optic nerve fibres. Buckling in the nonaxisymmetric state in the neighborhood of the edge could also cause edemas at the periphery of the LC and the atrophy of the optic nerve fibres. It is shown, that after decompression surgeries the shape of the LC deflection becomes more shallow, its relative value decreases, as a result of the sclera refinement. However the absolute LC deflection increases. Conclusion All considered models confirm the mechanical genesis of glaucoma and help to evaluate the deflection of LC in normal state and after decompression surgeries.