Narrow Results

Understanding the relationship between the changes in the axonal transport of the optic nerve (ON) and lamina cribrosa (LC) deformation will be helpful to estimate the degree of axonal transport block by measuring the LC deformation in vivo. First, the changes in the axonal transport of the ON were studied using an acute high intraocular pressure (IOP) model, which was established by perfusing saline water into the anterior chamber of cats. The IOP of cat was unilaterally elevated to and maintained at 30, 40, and 50mmHg. The axonal transport of the ON was examined by confocal laser scanning microscope. Then the deformations and stress distributions of the LC and ON were calculated using a three-dimensional finite element model of the LC microstructure including ON. The results showed axonal transport changes of ON increased with elevation of the IOPs. While Young’s modulus of the LC and ON were assumed as 0.1MPa and 0.03MPa, the numerical simulation results showed that LC had displacements of 0.02, 0.03, and 0.04mm backward at the IOPs of 30, 40, and 50mmHg, respectively. The calculated compressive strain applied to the ON were 0.0425, 0.0567, and 0.0709 under 30, 40, and 50mmHg IOP, respectively. The results of strain and stress analysis of LC and ON showed that the deformation of LC would compress the ON. The axonal transport abnormalities could be inferred by measuring the LC deformation in vivo.

A three-dimensional mathematical model is proposed that describes the ferroelectric response of polycrystalline ferroelectrics to an electric field in the absence of mechanical stresses. It is based on the separation of the switching process into two related parts: the rotation of the spontaneous polarization vectors and the destruction of the domain wall fixing mechanisms. For each of the parts, the energy costs are calculated, which are the components of the energy balance in the real polarization process. The constitutive relations for the induced and residual components of the polarization vector of the representative volume are obtained. A number of numerical experiments were performed, which showed good agreement with the experimental data.