CAJ | 학술논문

目的以有限元数字模拟近视准分子激光原位角膜磨镶术(LASIK),初步研究术后角膜后表面隆起度改变同各项参数之间的关系.方法计算机数字模拟研究.使用OrbscanⅡZ角膜地形图系统采集116只近视人眼角膜上各特定点的高度图数据,并计算各点坐标,以非线性回归拟合角膜前、后表面通用曲面方程；建立角膜的三维立体模型,模拟LASIK手术；引入生物力学参数进行有限元分析,研究术后角膜后表面隆起度改变同各项参数之间的关系.结果近视国人角膜前后表面均呈椭球形态,其前表面方程为:X2/8.78+Y2/8.68+(Z+9.79)2/9.792=1 (Residual=115.50,R2=0.99)；后表面为:X2/8.40+Y2/8.19+(Z+11.89)2/11.352=1 (Residual=96.63,R2=0.99).模拟结果示LASIK术后角膜后表面隆起度变化受弹性模量的影响最大,与角膜瓣厚度、光学区直径、眼内压及屈光不正矫治度数成正比.结论近视眼角膜前后表面均为椭球面,有限元分析结果证实角膜生物力学性能是影响LASIK矫治近视效果的一个重要因素.
목적 이유한원수자모의근시준분자격광원위각막마양술(LASIK),초보연구술후각막후표면륭기도개변동각항삼수지간적관계.방법 계산궤수자모의연구.사용OrbscanⅡZ각막지형도계통채집116지근시인안각막상각특정점적고도도수거,병계산각점좌표,이비선성회귀의합각막전、후표면통용곡면방정；건립각막적삼유입체모형,모의LASIK수술；인입생물역학삼수진행유한원분석,연구술후각막후표면륭기도개변동각항삼수지간적관계.결과 근시국인각막전후표면균정타구형태,기전표면방정위:X2/8.78+Y2/8.68+(Z+9.79)2/9.792=1 (Residual=115.50,R2=0.99)；후표면위:X2/8.40+Y2/8.19+(Z+11.89)2/11.352=1 (Residual=96.63,R2=0.99).모의결과시LASIK술후각막후표면륭기도변화수탄성모량적영향최대,여각막판후도、광학구직경、안내압급굴광불정교치도수성정비.결론 근시안각막전후표면균위타구면,유한원분석결과증실각막생물역학성능시영향LASIK교치근시효과적일개중요인소.
Objective To establish a biomechanical finite element model of myopic laser in situ keratomileusis (LASIK) and to study the relationship between various parameters and the elevation change of posterior corneal surface.Methods Computer numerical simulation study.Sixty-eight subjects (116 eyes) were measured with Orbscan ⅡZ corneal topography system.Selecting 110 eyes randomly from 116 eyes,all special points' coordinates of the 110 corneas were introduced to SAS statistical software to calculate the corneal surface equations through non-linear regression method and to compare the forecast results with the actual values.Constructing the corneal 3D model by ANSYS software,simulating LASIK by mathematical method,setting up biomechanical parameters,restraining boundary conditions,loading capacity,establishing the laser refractive corneal surgery model based on the biomechanical properties.The Z-axis displacement of posterior corneal surface apex was used as an observing index.Results The general equation of the anterior surface:X2/8.78+Y2/8.68+(Z+9.79)2/9.792=1 (Residual=115.50,R2=0.99),posterior surface:X2/8.40+Y2/8.19+(Z+ 11.89)2/11.352=1(Residual=96.63,R2=0.99).The correlation r between the measured Z-axis values and predicted Z-axis values of anterior and posterior corneal surface were both 0.99.The Z-axis displacement of posterior corneal surface apex correlated positively with flap thickness,optical zone diameter,intraocular pressure,negatively with the modulus of elasticity and refractive errors correction in the surgery simulation.The parameter that had the most effect on the hyperopic shift of the posterior surface was the modulus of elasticity.Conclusion The myopia anterior and posterior corneal surfaces are both ellipsoid.The finite element model shows that the modulus of elasticity has the most effect on the hyperopic shift of the posterior surface.The study will be able to provide other relevant basic information.