Higher-Order Aberrations Due to the Posterior Corneal Surface in Patients with Keratoconus
Higher-Order Aberrations Due to the Posterior Corneal Surface in Patients with Keratoconus
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DOI：
10.1167/iovs.08-2754
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发表时间：
2009-06-01
影响因子：
4.4
通讯作者：
Tano, Yasuo
中科院分区：
文献类型：
--
作者：
Nakagawa, Tomoya;Maeda, Naoyuki;Tano, Yasuo
目的.本研究旨在探讨圆锥角膜眼与正常眼相比，由于角膜后表面引起的高阶像差（HOA）。我们研究了24只正常眼和28只圆锥角膜眼。使用旋转Scheimpflug相机获得前/后角膜高度和角膜厚度测量数据。根据高度数据和最佳拟合球面之间的差异，使用每个角膜表面的原始程序计算6 mm瞳孔的HOA。测量的参考轴与主视线对齐。HOA用归一化Zernike多项式展开。对于三叶形、彗差、四叶形和二级散光的每对标准Zernike项，通过Zernike矢量分析计算幅度和轴的一个值。圆锥角膜前/后表面的平均总角膜HOA（均方根[μ m]）（分别为4.34/1.09）显著（P < 0.001）高于对照眼（0.46/0.15）。圆锥角膜前/后表面的三叶形、彗差和球面像差的每个Zernike矢量项的平均幅度（0.77/0.19，3.57/0.87，-0.44/0.17）分别显著（P < 0.001）高于对照眼（0.09/0.04，0.33/0.07，0.25/-0.07）。前表面（63.6 °）和后表面（241.9 °）引起的昏迷向量计算的平均轴向相反。圆锥角膜眼角膜两侧的HOA均高于对照眼。后表面的昏迷部分补偿了前表面的昏迷。戴硬性透气性角膜接触镜的圆锥角膜患者的残余不规则散光可以通过测量角膜后表面的HOA来估计。（Invest Ophthalmol维斯科学。2009; 50：2660-2665）DOI：10.1167/iovs.08-2754
PURPOSE. This study was designed to investigate higher-order aberrations (HOAs) due to the posterior corneal surface in keratoconic eyes compared with normal eyes.METHODS. We studied 24 normal and 28 keratoconic eyes. The anterior/posterior corneal heights and pachymetric data were obtained with a rotating Scheimpflug camera. HOAs for 6 mm pupils were calculated from the differences between the height data and the best-fit sphere, using an original program for each corneal surface. The reference axes of the measurements were aligned with the primary line of sight. The HOAs were expanded with normalized Zernike polynomials. For each pair of standard Zernike terms for trefoil, coma, tetrafoil, and secondary astigmatism, one value for the magnitude and axis was calculated by Zernike vector analysis.RESULTS. The mean total corneal HOAs (root mean square [mu m]) from the anterior/posterior surfaces were significantly (P < 0.001) higher in keratoconic (4.34/1.09, respectively) than in control eyes (0.46/0.15). The mean magnitude of each Zernike vector terms for trefoil, coma, and spherical aberration from the anterior/posterior surfaces was significantly (P < 0.001) higher in keratoconic (0.77/0.19, 3.57/0.87, -0.44/0.17) than control eyes (0.09/0.04, 0.33/0.07, 0.25/-0.07), respectively. The mean axes by vector calculation for coma due to the anterior (63.6 degrees) and posterior surfaces (241.9 degrees) were in opposite directions.CONCLUSIONS. Corneal HOAs on both corneal surfaces in keratoconic eyes were higher than in control eyes. Coma from the posterior surface compensated partly for that from the anterior surface. Residual irregular astigmatism in patients with keratoconus wearing rigid gas permeable contact lenses can be estimated by measuring the HOA from the posterior corneal surface. (Invest Ophthalmol Vis Sci. 2009; 50: 2660-2665) DOI:10.1167/iovs.08-2754