基于有限元分析的个体眼光学特性和视觉矫正研究

The biomechanical properties of the human eye may be changed from ophthalmic clinical surgery. These changes may induced the change of refractive state and have significant effects on optical property of the whole human eye, which concerns both the predictability of ophthalmic surgery and the outcomes of vision correction. Therefore it has significant the clinical application value to study the connection mechanism between the change of biomechanical properties of human eye and the optical properties of the whole human eye systematically. This project prepares to focus on analysing the effect of the operation parameters on the corneal shape change by building the customized finite element model of human eye. Then we study quantitatively the mechanism of the optical property changing with biomechanical properties of human eye after ophthalmic surgery by building the customized optical model with considering the corneal shape change. Futhermore, it may be verified that the corneal shape change has significant impact on the postoperative visual quality by the clinical experiment. These models are all based on the clinic individual data. The main contents of the project include:①Based on the clinical geometric data and classical biomechanical properties of the human eye, the three dimensional finite element models of the individual human eye will be built. Then, the simulations are performed on refractive and cataract surgery, and the influence of the surgery parameters on postoperative corneal shape will be studied. ②The optical models of the individual eyes will be built by combining the corneal shape change based on the clinical structure parameters, and then some optical characteristic parameters will be analyzed, such as monochromatic aberration. ③Finally, through the clinical data and theoretical data, we will provide statistical analysis that reveals the connection mechanism between the biomechanical properties and the postoperative optical properties of the whole human eye. The results may offer the new theoretical basis for improving the predictability of ophthalmic surgery, accurately evaluating and improving the outcomes of vision correction.

眼科手术往往改变人眼的生物力学特性，从而导致屈光状态发生变化并显著影响全眼光学特性，最终影响手术的预测水平和视觉效果，因此研究人眼生物力学特性变化与全眼光学特性的关联机制具有重要的应用价值。本项目拟采用临床个体数据为基础，正确构建个体化人眼有限元模型，明确手术参数对角膜形态变化的作用效果；构建考虑角膜形态变化的个体化光学模型，定量研究光学特性随生物力学特性的变化机理，并通过临床实验验证角膜形态改变对术后视觉质量有明显影响。内容包括：①基于临床几何参数和经典物理参数，建立个体化人眼有限元模型，模拟眼科手术，分析手术参数对术后角膜形态的影响；②基于临床结构参数，结合角膜形态改变量，建立个体化人眼光学模型，分析像差等光学特性参量；③综合临床测量数据和理论预测数据，统计分析人眼生物力学特性对术后光学特性的影响机理。研究结果可为提高手术预测水平、准确评估和提高术后视觉效果提供新的理论依据。

眼科手术往往改变人眼的生物力学特性，从而导致屈光状态发生变化并显著影响全眼光学特性，最终影响手术的预测水平和视觉效果，因此研究人眼生物力学特性变化与全眼光学特性的关联机制具有重要的应用价值。本项目基于临床测量的个体数据，构建个体化人眼有限元模型，系统地分析屈光手术对人眼生物力学特性的影响，并基于有限元分析结果构建光学模型，从而定量研究人眼像差等光学特性与生物力学特性之间的关联机制。取得的重要结果、关键数据等及其科学意义包括（1）构建了精确的人眼有限元模型，曲面的拟合精度达到了平均误差小于2微米，在此精度上才能更好的实现角膜LASIK手术和SMILE屈光手术的模型，保证模拟的可靠度。该模型的构建为眼科生物力学的后续研究提供了非常好的物质基础。（2）分析了角膜瓣厚度对LASIK手术后人眼角膜前后表面位移、应力和应变分布的影响，发现了角膜瓣的创建会大大影响人眼生物力学特性。研究结果可为眼科屈光手术医生提供参考，并可为眼科手术设备厂家提供改进手术方案提供理论基础。（3）分析了过渡区对常规屈光手术和个性化波前像差引导的屈光手术术后波前像差的影响，发现残余的术后高阶波前像差可以通过优化非球面过渡区类型来降低，从而达到提高术后视功能的目的。研究结果可为眼科屈光手术医生优化眼科手术参数提供理论依据，对全体屈光手术患者都有重要意义。（4）基于有限元模型分析了LASIK常规屈光手术后由于人眼生物力学改变而引入的波前像差，研究结果可为眼科屈光手术医生设计治疗方案提供参考，提高屈光手术的可预测性，降低手术风险。（5）分析了飞秒激光小切口角膜微透镜取出术（SMILE）屈光手术后人眼角膜前后表面位移、应力和应变分布以及由于人眼生物力学改变而引入的波前像差。研究结果可为优化眼科手术参数提供理论依据，提高临床眼科手术的安全性。研究方案和研究结果已经被天津市眼科医院用于临床，并取得了非常好的临床效果，经济效益和社会效益显著。