猪眼LASIK术后角膜的应力松弛和连续松弛谱(英文)  

Stress and continuous relaxation spectrum of porcine cornea after LASIK

作　　者：方学军[1] 徐艳春[1] 史天禹 张黎[2] 李子凡[2] 

机构地区：[1]中国医科大学附属第一医院眼科,中国辽宁省沈阳市110001 [2]沈阳爱尔眼视光医院,中国辽宁省沈阳市110003

出　　处：《国际眼科杂志》2007年第3期626-629,共4页International Eye Science

摘　　要：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1000s,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。AIM： To explore the characteristic of relaxation of porcine cornea after LASIK METHODS： Usual LASIK was corneas with stable intraoculer performed on fresh porcine 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 out 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 rate was 1..5, and relaxation time was 1 000s. The data were oollected electronically and automatically. RESLILT： In LASIK procedure, though a single flap-outting can cause a little reduction of corneal stress relaxation （P〈0.05, P=0.49）, the cornea may still remain its property of vico-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 speamen 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 vertical and longitudinal meridian specimens are similar, and slightly obvious in longitudinal specimen, especially in 70% ablation group.

关 键 词：LASIK 应力松弛 松弛谱 

分 类 号：R779.63[医药卫生—眼科]