不同进展期圆锥角膜生物力学研究

目的:探讨可视化角膜生物力学分析仪(Corvis ST)测量正常角膜、顿挫期圆锥角膜、亚临床期圆锥角膜、临床期圆锥角膜的生物力学变化,分析不同进展期圆锥角膜生物力学特征,为更早期地诊断圆锥角膜提供临床依据.方法:病例对照研究.选取顿挫期圆锥角膜15眼为顿挫组,亚临床期圆锥角膜23眼为亚临床期组,临床期圆锥角膜40眼为圆锥角膜组,欲行近视激光手术和正常角膜志愿者40眼为正常组(对照组),应用Corvis ST测定各组的生物力学参数,并进行比较分析,绘制受试者工作曲线(ROC).结果:正常角膜与顿挫期圆锥角膜生物力学各参数差异均无统计学意义(P>0.05).正常角膜与亚临床期组第二压平长度(AL2)、第一压平速率(AV1)、最大压陷曲率半径(HC-radius)、最大压陷深度(DA)间的差异有统计学意义(P<0.05).正常角膜与圆锥角膜组除第二压平速度(AV2)、最大压陷时间(HC-time)、最大压陷屈膝峰间距(PD)差异无统计学意义外,其余生物力学数据差异均有统计学意义(P<0.05),ROC曲线分析DA对于圆锥角膜诊断效率最高(曲线下面积0.891±0.028).结论:顿挫期圆锥角膜生物力学较正常角膜无改变,亚临床期圆锥角膜生物力学较正常角膜部分参数有改变,但其参数单独诊断圆锥角膜特异性和敏感性均较差.临床期圆锥角膜生物力学较正常角膜明显改变,DA诊断效率最高.

A biomechanical study of keratoconus at different stages of progression

AIM: To investigate and analyze the changes of corneal biomechanics of normal eyes, forme frusta keratoconus eyes, subclinical keratoconus eyes and clinical keratoconus eyes by Corneal visualization Scheimpflug technology(Corvis ST), and provide clinical basis for early diagnosis of keratoconus.

METHODS: Case-control study. We randomly selected 40 normal eyes as normal group, 15 forme frusta keratoconus eyes as forme frusta keratoconus group, 23 subclinical keratoconus eyes as subclinical keratoconus group, and 40 clinical keratoconus eyes as keratoconus group. The biomechanical parameters of each group were measured by Corvis ST. The receiver operating characteristic(ROC)curves was plotted to distinguish keratoconus from the normal cornea.

RESULTS: There was no significant difference in the parameters of biomechanics between normal group and forme frusta keratoconus group (P>0.05). Compared to normal group and subclinical keratoconus group, the parameters second applanation length(AL2), first velocity of applanation(AV1), central curvature radius at highest concavity(HC-radius), deformation amplitude(DA)were revealed statistically significant differences(P<0.05). The biomechanical parameters of the keratoconic group were significantly different from those of normal group except for the second velocity of applanation(AV2), time from the start until the highest concavity(HC-time), peak distance(PD). ROC curve showed that the DA(area under the curve:0.891±0.028)was the best predictive parameter to distinguish keratoconus from the normal eyes.

CONCLUSION: The corneal biomechanical parameters of forme frusta keratoconus group are not changed compared with normal group. The changes between normal group and subclinical keratoconus group should combine with other technology to further improve subclinical keratoconic screening. Compared with normal corneas, keratoconus has a great change in biomechanics, which DA diagnosis of the highest efficiency.