Epithelial and corneal thickness measurements by in vivo confocal microscopy through focusing (CMTF)
Epithelial and corneal thickness measurements by in vivo confocal microscopy through focusing (CMTF)
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DOI：
10.1076/ceyr.16.3.214.15412
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发表时间：
1997-03-01
影响因子：
2
通讯作者：
Jester, JV
中科院分区：
文献类型：
--
作者：
Li, HF;Petroll, WM;Jester, JV
目的.目的研究一种新的活体共焦显微镜穿透聚焦（CMTF）方法测量角膜总厚度、上皮厚度和Bowman层厚度的可行性。对兔以3 μ m/sec的平均焦平面速度，对人以64 μ m/sec的平均焦平面速度，从上皮到内皮扫描中央角膜。扫描最初被录像，后来被数字化。从数字图像，通过计算扫描中每个图像的中心180 × 180像素区域（285 μ m × 285 μ m）中的平均像素强度并绘制为z深度的函数来生成CMTF强度曲线。然后，使用一个程序将该强度分布图中的峰与独特的角膜层经验性地关联起来，该程序交互地显示对应于鼠标光标位置的图像，该鼠标光标位置沿强度分布图曲线沿着。然后从强度曲线中相关峰的z轴位置计算亚层厚度值。在研究中评估了10只正常家兔和7名人类志愿者。对兔眼进行CMTF和超声角膜厚度测量（UP），以确定CMTF和UP之间的一致性。所有10只兔眼均识别出明显的上皮、基底层和内皮峰。CMTF测量的兔子平均中央角膜厚度为381.6 +/-27.3 μ m，UP测量的平均中央角膜厚度为384.4 +/-28.7 μ m。CMTF和UP之间中央角膜厚度的平均差异为-2.8 +/-7.1 μ m，这在统计学上不显著（配对t检验p> 0.2）。通过CMTF测量的兔中央上皮厚度为47.7 +/-2.2 μ m。上皮和角膜厚度重复扫描的平均变异系数分别为2.5%和0.7%。所有家兔的上皮和角膜厚度的标准误差均小于1.5 μ m。上皮和角膜厚度测量的可重复性分别为2.2 μ m和2.6 μ m，计算为组内方差的平方根的单因素AN0VA.Intensity曲线为人类角膜显示出强大的上皮和内皮峰，以及较小的峰值对应于基底上皮神经丛和致密的前层基质角膜细胞核。人的平均中央角膜厚度为532.1 ± 18.8 μ m;中央上皮厚度为50.6 ± 3.9 μ m;中央Bowman层厚度为16.6 ± 1.1 μ m。重复扫描的平均变异系数分别为5.9%，13.2%和1.6%的上皮，鲍曼的层，和角膜厚度，分别。所有测量的标准误差小于2.4 μ m。上皮、Bowman层和角膜厚度测量的重复性分别为3.2 μ m、2.3 μ m和10.0 μ m。CMTF是一种新的、可重复的技术，用于在角膜的临床体内共焦显微镜检查期间获得上皮和角膜厚度测量值。更重要的是，该方法提供了用于测量和分析角膜亚层的深度和厚度的第一客观定量方法，这可以证明在时间上评估角膜功能方面具有独特价值。
Purpose. To study the feasibility of measuring total corneal thickness, as well as the thickness of the epithelium and Bowman's layer, using a novel irt vivo confocal microscopy through-focusing (CMTF) methodology.Methods. The central cornea was scanned from the epithelium to endothelium at an average focal plane speed of 3 mu m/sec for rabbits, and 64 mu m/sec for humans. Scans were initially video-recorded and later digitized. From digital images, CMTF intensity curves were generated by calculating the average pixel intensity in the central 180 X 180 pixel region (285 mu m X 285 mu m) of each image in the scan, and plotting as a function of z-depth. Peaks in this intensity profile were then empirically correlated to unique corneal layers using a program which interactively displayed images corresponding to the mouse cursor position along the intensity profile curve. Sub-layer thickness values were then calculated from the z-axis positions of the relevant peaks in the intensity curve. Ten normal rabbits and seven human volunteers were evaluated in the study. Both CMTF and ultrasonic pachymetry (UP) measurements were performed on rabbit eyes to determine the agreement between CMTF and UP.Results. Distinct epithelial, basal lamina, and endothelial peaks were identified for all 10 rabbit eyes. The mean central corneal thickness in the rabbit was 381.6 +/- 27.3 mu m by CMTF and 384.4 +/- 28.7 mu m by UP. The mean difference in central corneal thickness between CMTF and UP was -2.8 +/- 7.1 mu m which was not statistically significant (p > 0.2 by paired t-test). Central epithelial thickness in the rabbit measured by CMTF was 47.7 +/- 2.2 mu m. The average coefficients of variation for repeated scans were 2.5% and 0.7% for epithelial and corneal thickness, respectively. The standard errors for both epithelial and corneal thickness were less than 1.5 mu m for all rabbits. The reproducibilities for epithelial and corneal thickness measurements were 2.2 mu m and 2.6 mu m, respectively, calculated as the square root of the within group variances of One-Way ANOVA.Intensity profiles for human corneas showed strong epithelial and endothelial peaks, as well as smaller peaks corresponding to the basal-epithelial nerve plexus and the denser anterior layer of stromal keratocyte nuclei. The mean central corneal thickness in the human was 532.1 +/- 18.8 mu m; central epithelial thickness was 50.6 +/- 3.9 mu m: central Bowman's layer thickness was 16.6 +/- 1.1 mu m. The average coefficients of variation for repeated scans were 5.9%, 13.2%, and 1.6% for epithelial, Bowman's layer, and corneal thickness, respectively. The standard errors for all measurements were less than 2.4 mu m. The reproducibilities for epithelial, Bowman's layer, and corneal thickness measurements were 3.2 mu m, 2.3 mu m, and 10.0 mu m, respectively.Conclusions. CMTF is a novel, reproducible technique for obtaining epithelial and corneal thickness measurements during clinical in vivo confocal microscopy of the cornea. Mole importantly, this methodology provides the first objective, quantitative approach for measurement and analysis of depth and thickness of corneal sub-layers which may prove uniquely valuable in temporally assessing corneal function.