基于中国本土人口数据构建的新角膜生物力学指数(cCBI)对中国人圆锥角膜和亚临床圆锥角膜的诊断效能

Diagnostic capability of Corvis Biomechanical Index for Chinese populations in keratoconus and subclinical keratoconus

目的探讨基于中国本土人口数据构建的新角膜生物力学指数(cCBI)对中国人圆锥角膜和亚临床圆锥角膜的诊断能力。方法病例对照研究。本研究共纳入天津市眼科医院收治的眼病患者558例(558眼)。其中,双侧圆锥角膜患者200例(200眼),记为圆锥角膜组;单侧圆锥角膜患者112例(112眼),记为亚临床圆锥角膜组;预行屈光手术的屈光不正患者246例(246眼),记为对照组。采用德国Pentacam眼前节分析系统进行角膜地形图检查,应用Scheimpflug相机获取患者眼前节图像,合成受试者眼前节三维立体图像。使用德国Oculus公司生产的可视化角膜生物力学分析仪进行角膜生物力学检查,应用超高速Scheimpflug断层扫描技术以每秒4330帧的速度对患眼进行扫描,在喷气脉冲作用下采集140幅图像。使用受试者操作特征(ROC)曲线分析原有的CBI、cCBI、Belin/Ambrósio增强扩张显示(BAD)、断层扫描联合生物力学指数(TBI)诊断圆锥角膜、亚临床圆锥角膜的能力,并通过诊断能力最佳时所对应的截断值计算诊断亚临床圆锥角膜的敏感值。使用DeLong检验进一步分析ROC曲线下面积(AUC),比较cCBI和原有的CBI诊断圆锥角膜和亚临床圆锥角膜的准确性。结果BAD、原有的CBI、cCBI、TBI对圆锥角膜均显示出优异的诊断能力(均为AUC≥0.900),其中TBI和BAD的诊断能力最佳,AUC均高达1.000,cCBI(AUC=0.999)对圆锥角膜诊断能力优于原有的CBI(AUC=0.995)。BAD、原有的CBI、cCBI、TBI对亚临床圆锥角膜均显示出较好的诊断能力(均为AUC≥0.800),其中cCBI诊断能力最佳,AUC可达0.891,优于原有的CBI(AUC=0.856)、TBI(AUC=0.856)和BAD(AUC=0.847)。诊断圆锥角膜的cCBI和原有的CBI的截断值分别为0.105、0.635。cCBI对亚临床圆锥角膜诊断的准确性仍高于原有的CBI,且DeLong检验显示二者之间的差异有统计学意义(Z=1.985,P=0.047)。其中诊断亚临床圆锥角膜的cCBI和原有的CBI的截断值分别为0.014、0.362。结论基于中国本土人口数据构建的cCBI更适用于筛查中国人的早期圆锥角膜。

Objective To evaluate the accuracy of the Corvis Biomechanical Index for Chinese populations(cCBI)on the diagnosis of keratoconus(KC)and subclinical keratoconus(SKC).Methods A case-control study was conducted.A total of 558 patients(558 eyes)were included and divided into the KC group(200 eyes of 200 patients with bilateral keratoconus),SKC group(112 eyes of 112 patients with unilateral keratoconus),and control group(246 eyes of 246 patients with refraction error who intended to receive the refractive surgery).The Pentacam anterior segment analysis system(Germany)was used for a corneal topography examination.The anterior segment images were obtained by the Scheimpflug camera,and the three-dimensional anterior segment images were synthesized.The Oculus Corvis ST(Germany)was used for the corneal biomechanical examination,and the affected eyes were scanned at a rate of 4330 frames per second using ultra-high-speed Scheimpflug tomography,and 140 images were acquired under the action of jet pulses.Receiver operating characteristic(ROC)curves were used to analyze the ability of original Corvis Biomechanical Index(CBI),cCBI,Belin/Ambrósio Enhanced Ectasia Display(BAD)and Tomographic and Biomechanical Index(TBI)to diagnose KC and SKC,and the sensitivity value for SKC diagnosis was calculated with the cut-off value corresponding to the optimal diagnostic ability.DeLong test was used to analyze the area under the curve(AUC)and compare the accuracy of CBI and cCBI to diagnose KC and SKC.Results The BAD,CBI,cCBI and TBI all showed excellent diagnostic capability on KC(all AUC≥0.900);among them,TBI and BAD showed the best diagnostic ability(both AUC=1.000).The diagnostic ability of cCBI(AUC=0.999)in KC was superior to that of CBI(AUC=0.995).The BAD,CBI,cCBI and TBI all showed excellent diagnostic capability on SKC(all AUC≥0.800);among them,cCBI showed the best diagnostic ability,with an AUC up to 0.891,which is superior to CBI(AUC=0.856),TBI(AUC=0.856)and BAD(AUC=0.847).The cut-off values of cCBI and CBI for KC diagnosis were 0.105 and 0.635,respectively.The accuracy of cCBI was superior to CBI in diagnosing SKC,and DeLong’s test showed a significant difference between the two(Z=1.985,P=0.047).The cut-off values of cCBI and CBI for SKC diagnosis were 0.014 and 0.362,respectively Conclusion The cCBI is more suitable for screening early KC in Chinese people.