Abstract：
To investigate the optimal cutting depth (Cap) in small incision lenticule extraction from the perspective of corneal biomechanics, a three-dimensional finite element model of the cornea was established using a stromal sub-regional material model to simulate small incision lenticule extraction. The displacement difference PΔ at the central point of the posterior corneal surface before and after lenticule extraction, as well as the von Mises stress at four points of different thicknesses in the center of the cornea, were analyzed using the finite element model considering the hyperelastic property and the difference in stiffness between the anterior and posterior of the cornea. The numerical curves of PΔ-Cap and von Mises Stress-Cap relations at different diopters show that the displacement difference PΔ has a smallest value at the same diopter. In this case, the von Mises stress at four points with different thicknesses in the center of the cornea was also minimal. Which means that the optimal cutting depth exsisting in the cornea. Moreover, PΔ-Cap curves for different depth of stromal stiffness boundaries show that the optimal cap thickness would change with the depth of the stromal stiffness boundary. These results are of guiding significance for accurately formulating small incision lenticule extraction surgery plans and contribute to the advancement of research on the biomechanical properties of the cornea.
摘要：
从角膜生物力学的角度探讨小切口微透镜摘除的最佳切割深度(Cap)。利用基质亚区域材料模型建立角膜三维有限元模型，模拟小切口微透镜摘除。微透镜取出前后角膜后表面中心点的位移差PΔ,以及在角膜中心四个不同厚度点处的vonMises应力，使用有限元模型进行分析，考虑了角膜前后的超弹性和刚度差异。不同屈光度下PΔ-Cap和vonMises应力-Cap关系的数值曲线表明，在相同屈光度下，位移差PΔ具有最小值。在这种情况下,在角膜中心具有不同厚度的四个点上的vonMises应力也很小。这意味着最佳切割深度存在于角膜中。此外，对于基质刚度边界的不同深度的PΔ-Cap曲线表明，最佳盖厚度会随着基质刚度边界的深度而变化。这些结果对准确制定小切口微透镜摘除手术方案具有指导意义,有助于推进角膜生物力学特性的研究。
