Foveoschisis prediction based analysis of macular retina OCT-scan. Part II. Prediction of microcavity growth in retinal foveoschisis

Introduction. Increasing the number and size of microcavities in the retina is an important clinical manifestation of foveoschisis progression. However, there are no data about the patterns change shape and size of microcavities in the retina in the foveoschisis progression. Purpose. To develop quantitative criteria for predicting foveoschisis development in high axial myopia based on the average concentration of microcavities in retinal volume and based on the energy balance in the framework of nonlinear elastic-plastic medium. Material and methods. We examined 7 patients (14 eyes) with high axial myopia and myopic maculopathy. All patients underwent a spectral optical coherence tomography. Mathematical methods in the theory of destruction of elastic and elastic-plastic materials were applied. Results. The quantitative criteria for predicting foveoschisis development in high axial myopia based on the average concentration of microcavities in retinal volume and based on the energy balance in the framework of nonlinear elastic-plastic medium was set. In the first case in the formula for calculating the risk of progression foveoschisis accounted size of the plastic stress at the edge of a void in the retina (al), the distance between the micro-cavities (Al). If al>Al, then there is a merge of microcavities and progression foveoschisis. In the second case, the mathematical solution is reduced to the determination of destruction energy disclosure in a continuous medium. This takes into account the Poisson ratio of the retina, the Young's modulus, the intraocular pressure, the size of a void in the retina, the stress intensity factor in the thickness of the retina. Practical use of the criteria found to predict foveoschisis progression involves determining intraocular pressure and the maximum linear dimension of a void in the thickness of the retina accord- ing to the spectral optical coherence tomography. In the calculations, take intoaccount the biophysical properties of the retina.