Eye Hospital, Wenzhou Medical University, Wenzhou, 325027, China.
QuanZhou Women's and Children's Hospital, QuanZhou, 362000, China.
Sci Rep. 2017 Dec 12;7(1):17457. doi: 10.1038/s41598-017-17658-7.
To assess repeatability of corneal tomography in successive measurements by Pentacam in keratoconus (KC) and normal eyes based on the Iterative Closest Point (ICP) algorithm. The study involved 143 keratoconic and 143 matched normal eyes. ICP algorithm was used to estimate six single and combined misalignment (CM) parameters, the root mean square (RMS) of the difference in elevation data pre (PreICP-RMS) and post (PosICP-RMS) tomography matching. Corneal keratometry, expressed in the form of M, J and J (power vector analysis parameters), was used to evaluate the effect of misalignment on corneal curvature measurements. The PreICP-RMS and PosICP-RMS were statistically higher (P < 0.01) in KC than normal eyes. CM increased significantly (p = 0.00), more in KC (16.76 ± 20.88 μm) than in normal eyes (5.43 ± 4.08 μm). PreICP-RMS, PosICP-RMS and CM were correlated with keratoconus grade (p < 0.05). Corneal astigmatism J was different (p = 0.01) for the second tomography measurements with misalignment consideration (-1.11 ± 2.35 D) or not (-1.18 ± 2.35 D), while M and J kept similar. KC corneas consistently show higher misalignments between successive tomography measurements and lower repeatability compared with healthy eyes. The influence of misalignment is evidently clearer in the estimation of astigmatism than spherical curvature. These higher errors appear correlated with KC progression.
评估基于迭代最近点（ICP）算法的 Pentacam 在圆锥角膜（KC）和正常眼中连续测量的角膜断层扫描的可重复性。该研究涉及 143 例圆锥角膜和 143 例匹配的正常眼。ICP 算法用于估计六个单独和组合的对准（CM）参数，以及预（PreICP-RMS）和后（PosICP-RMS）断层扫描匹配的高程数据差异的均方根（RMS）。角膜屈光度以 M、J 和 J（功率向量分析参数）的形式表示，用于评估对准对角膜曲率测量的影响。PreICP-RMS 和 PosICP-RMS 在 KC 中比正常眼显着更高（P < 0.01）。CM 显着增加（p = 0.00），在 KC 中（16.76 ± 20.88 μm）比在正常眼中（5.43 ± 4.08 μm）更多。PreICP-RMS、PosICP-RMS 和 CM 与圆锥角膜分级相关（p < 0.05）。考虑到对准的第二次断层扫描测量的角膜散光 J 不同（p = 0.01）（-1.11 ± 2.35 D）或不考虑对准（-1.18 ± 2.35 D），而 M 和 J 保持相似。与健康眼相比，KC 角膜在连续的断层扫描测量之间始终显示出更高的对准误差和更低的可重复性。对准误差的影响在散光的估计中显然比球性曲率更明显。这些更高的误差似乎与 KC 的进展有关。
