Pentacam HR和RTVue OCT测量圆锥角膜的角膜厚度及最薄点位置的比较

Comparative study of corneal thickness and thinnest point position of keratoconus measured by Pentacam HR and RTVue OCT

目的:比较圆锥角膜患者行Pentacam HR角膜地形图和RTVue OCT检测的角膜厚度及最薄点位置的差异性、相关性和一致性。方法:横断面比较研究。使用Pentacam HR和RTVue OCT两种测量方法检测得到角膜曲率图、角膜厚度图、最薄点位置及最薄点厚度。符合正态分布数据采用配对样本t检验,不符合正态分布数据采用配对样本的秩和检验,两种测量方法的相关性和一致性分别采用Spearman相关分析和Bland-Altman分析。结果:本研究共包括圆锥角膜患者63例105眼,其中男49例(77.8%),女14例(22.2%),年龄22.24±6.19岁;其中Pentacam HR地形图相关数据:角膜曲率平均值(Km)为47.85±4.73D,角膜最大曲率值(Kmax)为55.43±8.72D。圆锥角膜患者中Pentacam HR比RTVue OCT测量的中央角膜厚度和最薄点厚度平均值厚4.70μm和19.46μm,均具有差异(P<0.05)。两种设备测得的最薄点位置的横坐标和纵坐标比较均无差异(P>0.05)。两种设备测得的中央角膜厚度、最薄点厚度均呈高度相关,最薄点位置的横坐标呈中度相关、最薄点位置的纵坐标呈弱相关。Bland-Altman分析结果显示两种设备测得的中央角膜厚度、最薄点厚度、最薄点位置的横坐标、最薄点位置的纵坐标分别有95.2%(100/105)、93.3%(98/105)、95.2%(100/105)、95.2%(100/105)的点在95%一致性界限以内,一致性范围分别为-36.00~+26.62μm、-42.27~+3.36μm、-0.80~+0.84mm、-1.95~+1.06mm。结论:在圆锥角膜中Pentacam HR比RTVue OCT检测的中央角膜厚度和最薄点厚度高,两仪器测量的中央角膜厚度和最薄点厚度的一致性范围较大,临床工作使用中不建议将二者测量值替换使用。两仪器测量圆锥角膜的角膜最薄点位置相当、一致性较好,临床工作使用中可考虑将二者测量值替换使用。

AIM:To investigate the difference,correlation,and consistency of corneal thickness and the thinnest point position detected by Pentacam HR corneal topography map and RTVue optical coherence tomography(OCT)in patients with keratoconus.METHODS:Cross-sectional comparative study.The corneal curvature map,corneal thickness map,thinnest point position,and thinnest point thickness were detected by Pentacam HR and RTVue OCT.Paired sample t-test was used for data consistent with normal distribution,and paired sample rank sum test was used for data inconsistent with normal distribution.Spearman correlation analysis and Bland-Altman analysis were used for the correlation and consistency of the two measurement methods.RESULTS:A total of 63 patients(105 eyes)with keratoconus were included in this study,including 49 males(77.8%)and 14 females(22.2%),aged 22.24±6.19 years;among them,relevant data of Pentacam HR topographic map:Km was 47.85±4.73D and Kmax was 55.43±8.72D.In measuring central corneal thickness and the thinnest point thickness of keratoconus,the Pentacam HR was 4.70μm and 19.46μm thicker than the mean value measured by RTVue OCT(P<0.05).There was no significant difference between the horizontal and vertical coordinates of the thinnest points measured by the two devices(P>0.05).The central corneal thickness and the thinnest point thickness measured by the two devices were highly correlated,the horizontal coordinate of the thinnest point was moderately correlated,and the vertical coordinate of the thinnest point was weakly correlated.Bland-Altman analysis showed that the central corneal thickness,the thinnest point thickness,the horizontal coordinate of the thinnest point,and the vertical coordinate of the thinnest point were 95.2%(100/105)and 93.3%(98/105),95.2%(100/105),95.2%(100/105)respectively,which were within the 95%consistency limit,while the consistency ranges were-36.00~+26.62μm,-42.27~+3.36μm,-0.80~+0.84mm,and-1.95~+1.06mm,respectively.CONCLUSION:In keratoconus,the central corneal thickness and the thinnest point thickness measured by Pentacam HR were higher than those measured by RTVue OCT.It is not recommended that the central corneal thickness and the thinnest point thickness measured by the two instruments be interchangeable in clinical use because of the wide range of consistency between the two instruments’results.The position of the thinnest corneal point measured by the two instruments is similar and consistent,so it could be considered to replace the measured values of the two instruments in clinical use.