圆锥角膜与LASIK术后角膜生物力学变化

Biomechanical changes in keratoconus and post-LASIK

目的 了解LASIK术后角膜生物力学变化的规律.方法 前瞻性病例对照研究.采用分层随机法选择圆锥角膜50眼和年龄相匹配的预行LASIK手术的50眼;测量LASIK术前、术后1周、术后6个月角膜滞后量（CH）、角膜阻力因子（CRF）值,并与圆锥角膜患者相应的角膜参数进行比较.对LASIK术前、术后1周、术后6个月及圆锥角膜的生物力学数据行正态性检验及方差齐性检验,各时间点差异行重复测量的方差分析,2组之间的差异行u检验.结果 LASIK术前CH[（10.25±2.44）mmHg]及CRF[（10.97±2.33）mmHg]明显高于术后1周[（7.84±1.25）mmHg、（7.47±1.13） mmHg]及术后6个月[（8.33±1.16）mmHg、（8.18±1.33）mmHg],差异具有统计学意义;术后6个月角膜生物力学值较术后1周时有回升;圆锥角膜患者的CH[（7.19±1.35）mmHg]、CRF[（7.15±1.46）mmHg]与LASIK患者术后1周角膜CH、CRF值差异无统计学意义,与术后6个月差异有统计学意义（t=-3.60、-3.05,P＜0.01）.结论 角膜屈光手术后角膜CH、CRF值呈先下降后上升的趋势,提示早期角膜保护的重要性.

Objective To analyze corneal biomechanical changes post laser in situ keratomileusis （LASIK）.Methods This was a prospective case-control study.The study included a stratified sample of 50 LASIK eyes and 50 keratoconus eyes.Corneal hysteresis （CH） and the corneal resistance factor （CRF） were measured before surgery and 1 week and 6 months after surgery.The results were compared to the keratoconus group.A normal distribution test and homogeneity test of variance were used to analyze the data.Repeated measures ANOVA was used to compare the groups.Results The average CH and CRF before LASIK were 10.25±2.44 and 10.97±2.33 mmHg.These values were much higher than values 1 week after the surgery （7.84±1.25 and 7.47±1.13mmHg） and 6 months after surgery （8.33±1.16 and 8.18±1.33 mmHg）.Corneal biomechanics at 6 months after the surgery were higher than those 1 week after surgery.There were no differences between the keratoconus and LASIK groups 1 week after surgery （7.19±1.35 and 7.15±1.46 mmHg）,but there were significant differences 6 months after surgery （t=-3.60,-3.05,P＜0.01）.Conclusion After LASIK,the CH and CRF initially declined and then increased,indicating the importance of early protection of the cornea.