Ravikumar Ayeswarya, Marsack Jason D, Benoit Julia S, Anderson Heather A
*PhD †PhD, FAAO ‡OD, PhD, FAAO College of Optometry (AR, JDM, JSB, HAA) and Texas Institute for Measurement, Evaluation and Statistics (JSB), University of Houston, Houston, Texas.
Optom Vis Sci. 2016 Nov;93(11):1356-1363. doi: 10.1097/OPX.0000000000000987.
To assess the repeatability of simulated keratometry measures obtained with Zeiss Atlas topography for subjects with and without Down syndrome (DS).
Corneal topography was attempted on 140 subjects with DS and 138 controls (aged 7-59 years). Subjects who had at least three measures in each eye were included in analysis (DS: n = 140 eyes (70 subjects) and controls: n = 264 eyes (132 subjects)). For each measurement, the steep corneal power (K), corneal astigmatism, flat K orientation, power vector representation of astigmatism (J0, J45), and astigmatic dioptric difference were determined for each measurement (collectively termed keratometry values here). For flat K orientation comparisons, only eyes with >0.50 DC of astigmatism were included (DS: n = 131 eyes (68 subjects) and control: n = 217 eyes (119 subjects)). Repeatability was assessed using (1) group mean variability (average standard deviation (SD) across subjects), (2) coefficient of repeatability (COR), (3) coefficient of variation (COV), and (4) intraclass correlation coefficient (ICC).
The keratometry values showed good repeatability as evidenced by low group mean variability for DS versus control eyes (≤0.26D vs. ≤0.09D for all dioptric values; 4.51° vs. 3.16° for flat K orientation); however, the group mean variability was significantly higher in DS eyes than control eyes for all parameters (p ≤ 0.03). On average, group mean variability was 2.5 times greater in the DS eyes compared to control eyes across the keratometry values. Other metrics of repeatability also indicated good repeatability for both populations for each keratometry value, although repeatability was always better in the control eyes.
DS eyes showed more variability (on average: 2.5×) compared to controls for all keratometry values. Although differences were statistically significant, on average 91% of DS eyes had variability ≤0.50D for steep K and astigmatism, and 75% of DS eyes had variability ≤5 degrees for flat K orientation.
评估使用蔡司阿特拉斯角膜地形图仪对唐氏综合征（DS）患者和非DS患者进行模拟角膜曲率测量的可重复性。
对140例DS患者和138例对照者（年龄7 - 59岁）进行角膜地形图检查。每只眼睛至少有三次测量结果的受试者纳入分析（DS组：n = 140只眼（70名受试者）；对照组：n = 264只眼（132名受试者））。每次测量时，确定每只眼睛的陡峭角膜屈光力（K）、角膜散光、平坦K轴方向、散光的屈光力矢量表示（J0、J45）以及散光的屈光度差值（此处统称为角膜曲率值）。对于平坦K轴方向比较，仅纳入散光>0.50DC的眼睛（DS组：n = 131只眼（68名受试者）；对照组：n = 217只眼（119名受试者））。使用以下方法评估可重复性：（1）组内均值变异性（受试者间平均标准差（SD））、（2）重复性系数（COR）、（3）变异系数（COV）和（4）组内相关系数（ICC）。
角膜曲率值显示出良好的可重复性，DS组与对照组眼睛的组内均值变异性较低（所有屈光度值分别为≤0.26D对≤0.09D；平坦K轴方向分别为4.51°对3.16°）即可证明；然而，所有参数在DS组眼睛中的组内均值变异性均显著高于对照组眼睛（p≤0.03）。在角膜曲率值方面，DS组眼睛的组内均值变异性平均比对照组眼睛大2.5倍。其他可重复性指标也表明，对于每个角膜曲率值，两组人群均具有良好的可重复性，尽管对照组眼睛的可重复性始终更好。
对于所有角膜曲率值，DS组眼睛与对照组相比显示出更大的变异性（平均：2.5倍）。尽管差异具有统计学意义，但平均而言，91%的DS组眼睛陡峭K值和散光的变异性≤0.50D，75%的DS组眼睛平坦K轴方向的变异性≤5度。
