Optovue iVue OCT测量角膜厚度的可重复性及其与Pentacam、Visante OCT的一致性研究

Repeatability of corneal thickness measurement with Optovue iVue OCT and a comparative study with Pentacam and Visante OCT

背景 角膜厚度测量对角膜屈光手术和眼病的诊断具有重要意义,Optovue iVue OCT是测量角膜厚度的新型频域OCT,了解其测量角膜厚度的可重复性及其与目前常用的Pentacam、Visante OCT的一致性,有助于对其临床应用价值进行客观评价. 目的 评价Optovue iVue OCT测量角膜厚度的可重复性,分析其与Pentacam三维眼前节分析诊断系统、Visante OCT测量角膜厚度的一致性. 方法 选取45例拟行角膜屈光手术的近视患者的右眼,分别用Optovue iVue OCT、Pentacam、Visante OCT对角膜最薄点、中央点和距角膜中央1 mm的3：00、6：00、9：00、12：00位进行厚度测量,采用组内相关系数（ICC）对Optovue iVue OCT 3次测量的可重复性进行分析,采用Bland-Altman一致性检验分析Optovue iVue OCT与Pentacam、Visante OCT的一致性;对Optovue iVue OCT所测8个象限的平均角膜厚度进行分析. 结果 Optovue iVue OCT在6个点的3次角膜厚度测量结果差异无统计学意义（P=0.546）,角膜最薄点、中央点、距角膜中央半径1 mm的3：00、6：00、9：00、12：00位ICC分别为99.92％、99.99％、99.96％、99.99％、99.99％和99.97％;Optovue iVue OCT、Visante OCT、Pentacam在6个点所测的角膜厚度值组间比较差异均有统计学意义（P=0.000、0.001、0.000、0.003、0.002、0.000）.两两比较结果显示,Optovue iVue OCT所测6个点角膜厚度值比Pentacarm测量值平均低24.20 μm,差异均有统计学意义（P=0.000、0.001、0.000、0.003、0.004、0.000）,一致性检验差异较大.Optovue iVue OCT测量的角膜厚度与Visante OCT比较,除12：00位差异有统计学意义（P=0.016）外,其余各点差异均无统计学意义（P=1.000、0.447、0.239、1.000、1.000）,一致性较好.Pentacam所测角膜厚度值比Visante OCT测量值平均高14.01 μm,除中央点差异无统计学意义（P=0.056）外,其余各点差异均有统计学意义（P=0.009、0.005、0.034、0.017、0.008）,一致性较差.Optovue iVue OCT所测8个象限平均角膜厚度颞下象限最薄者23例,占51.11％,上方和鼻上象限最厚者各21例,分别占46.66％. 结论 Optovue iVue OCT测量角膜厚度重复性好,其测量值与Visante OCT一致性好,但与Pentacam测量角膜厚度一致性差异较大,互相替代使用时应慎重.Optovue iVue OCT所测各象限平均角膜厚度大多数颞下象限最薄,鼻上、上方象限较厚.

Background Measurement of corneal thickness is of great significance for the design of refractive surgery and the diagnosis of eye diseases,measuring equipments and technology develop rapidly in recent years.Optovue iVue OCT is a new frequency-domain optical coherence tomography （OCT）,to compare its results with those of Pentacam and Visante OCT is helpful to objectively assess the clinical value of Optovue iVue OCT.Objective This study was to investigate the repeatability of corneal thickness measurement with Optovue iVue OCT and the comparatbility with Pentacam three-dimensional anterior segment analysis diagnostic system and Visante OCT.In addition,this study attempted to analyze the distribution of average corneal thickness in each quadrant by Optovue iVue OCT.Methods The corneal thicknesses of the corneal thinnest point,the central point and 3：00,6：00,9：00,12：00 zones 1 mm away from the center of the cornea were measured in 45 right eyes of 45 subjects with myopia using Optovue iVue OCT,Pentacam and Visante OCT in Tianjin Eye Hospital.Interclass correlation coefficient （ICC） was used to analyze the repeatability of measurement by Optovue iVue OCT.The agreements between Optovue iVue OCT and Pentacam or Visante OCT were evaluated by Bland-Altman test.The corneal area of 1.0-2.5 mm away from the center was divided into eight quadrants and the average corneal thickness of each quadrant was measured and analysis with Optovue iVue OCT.Results No significant difference was found in corneal thickness values for 3 times by Optovue iVue OCT （P=0.546）.The ICC by Optovue iVue OCT was 99.92%,99.99%,99.96%,99.99%,99.99% and 99.97% at the corneal thinnest point,the central point and 3：00,6：00,9：00,12：00 zones respectively.There were significant differences among the 3 kinds of methods （P =0.000,0.001,0.000,0.003,0.002,0.000）.The measured values of Optovue iVue OCT were significantly lower mean 24.20 μm than those of Pentacam （P=0.000,0.001,0.000,0.003,0.004,0.000）,but only the value at 12：00 zone of Optovue iVue OCT was evidently declined in comparison with that of Visante OCT （P =0.016）,there were no significant differences between all the other zones （P =1.000,0.447,0.239,1.000,1.000）.While the mean corneal thickness value from Pentacam lowed by 14.01 μm in comparison with Visante OCT,all zones had significant differences （P =0.009,0.005,0.034,0.017,0.008） except the central point （P =0.056）.Based on the Optovue iVue OCT,the thinnest zone was at temporal quadrant in 23 eyes （accounting for 51.11%） and at superior quadrant or super nasal quadrant in 21 eyes （both at 46.66%）.Conclusions Optovue iVue OCT measurement of corneal thickness is of high repeatability and is consistent with Visante OCT in myopic eye.Optovue iVue OCT shows evident difference from Pentacam in the measurement of corneal thickness.The thinnest point of the cornea is mainly in the inferior temporal quadrant and the thickest point is commonly in superior quadrant and nasal superior quadrant based on Optovue iVue OCT.