CAJ | 학술논문

目的:探讨猪眼LASIK术后角膜的应力松弛特征方法:新鲜猪眼,经视神经灌注维持眼压恒定,行常规LASIK手术,基质床分别切削30%,50%,70%整体角膜厚度,用自制的模具尺,切取哑铃型试件,200mL/L人血白蛋白液浸泡,冰箱4℃过夜保存.将试样吸干蛋白液,置于自制夹具固定,于美国Tytron250力学实验机做应力松弛实验.应力松弛突加载荷的加载速率为385mm/min,伸长比为1.5,松弛时间1 000s,计算机自动采集数据.结果:LASIK手术中,单纯切开角膜瓣即导致了角膜的应力松弛程度降低,P＜0.05(P=0.49),但是程度不大,可能角膜依然保持其粘弹特性.当激光消融30%角膜整体厚度及大于此值时,角膜的应力松弛程度几乎下降了一倍,P＜0.01.在LASIK手术中角膜的纵向应力松弛程度不如横向的变化明显,尤其是在70%切削深度条件下,角膜的横向应力松弛程度小于纵向应力松弛程度,有显著的统计学差异(P＜0.001).结论:猪眼角膜在横向上的应力松弛程度与纵轴方向的应力松弛程度相似,猪眼角膜LASIK手术后,角膜横轴方向的应力松弛程度小于纵轴方向应力松弛程度,在70%角膜厚度的切削深度时,差异有显著性意义.猪眼LASIK手术中,切削深度越深,角膜的应力松弛程度越差,也就越容易引起角膜的形变和蠕变.
목적:탐토저안LASIK술후각막적응력송이특정방법:신선저안,경시신경관주유지안압항정,행상규LASIK수술,기질상분별절삭30%,50%,70%정체각막후도,용자제적모구척,절취아령형시건,200mL/L인혈백단백액침포,빙상4℃과야보존.장시양흡간단백액,치우자제협구고정,우미국Tytron250역학실험궤주응력송이실험.응력송이돌가재하적가재속솔위385mm/min,신장비위1.5,송이시간1 000s,계산궤자동채집수거.결과:LASIK수술중,단순절개각막판즉도치료각막적응력송이정도강저,P＜0.05(P=0.49),단시정도불대,가능각막의연보지기점탄특성.당격광소융30%각막정체후도급대우차치시,각막적응력송이정도궤호하강료일배,P＜0.01.재LASIK수술중각막적종향응력송이정도불여횡향적변화명현,우기시재70%절삭심도조건하,각막적횡향응력송이정도소우종향응력송이정도,유현저적통계학차이(P＜0.001).결론:저안각막재횡향상적응력송이정도여종축방향적응력송이정도상사,저안각막LASIK수술후,각막횡축방향적응력송이정도소우종축방향응력송이정도,재70%각막후도적절삭심도시,차이유현저성의의.저안LASIK수술중,절삭심도월심,각막적응력송이정도월차,야취월용역인기각막적형변화연변.
AIM: To explore the characteristic of relaxation of porcine cornea after LASIKMETHODS: Usual LASIK was performed on fresh porcine corneas with stable intraoculer pressure (IOP) maintained through optic nerve irrigation. The ablation depth on stroma is 30%, 50% and 70% respectively. Then the dumbbell-shaped corneal strip specimens were cut and stored in 20% Human Albumin solution for use (4℃).Sip up the Albumin solution on specimens, and fixed them on homemade jig. Stress relaxation tests were erformed on Tytron250 Dynamics Experiment System. the loading speed was 385mm/min,extending ratewas 1.5, and relaxation time was 1 000s. The data werecollected electronically and automatically.RESULTS: In LASIK procedure, though a single flap-cutting can cause a little reduction of corneal stress relaxation (P＜0.05,P=0.49), the cornea may still remain its property of visco-elasticity. When ablation depth was 30% or more, corneal stress relaxation decreased to almost one half (P＜0.01).The change of corneal stress relaxation degree in vertical meridian specimen was lower than that in horizontal specimen, especially when ablation depth was 70%, and it's statistically significant (P＜0.001). In LASIK operation, the more depth the ablation, the more reduce the stress relaxation degree, and it's easy to cause deformation and creep deformation.CONCLUSION: The changes of the stress relaxation in verticai and longitudinal meridian specimens are similar, and slightly obvious in longitudinal specimen, especially in 70%ablation group.