傅立叶域光学相干断层扫描仪测量LASIK术后角膜参数的重复性和准确性

目的 研究RTVue傅立叶域光学相干断层扫描仪（FD-OCT）测量准分子激光原位角膜磨镶术（LASIK）后角膜参数的重复性与准确性。方法 前瞻性研究。接受LASIK手术者58例（58眼），均选择右眼进行研究，术前及术后3个月行主觉验光。术前IOL Master测量角膜屈光力，术后3个月使用RTVue FD-OCT测量角膜中央3 mm直径范围内前表面曲率半径（Ranterior）、后表面曲率半径（Rposterior）、角膜后前表面曲率半径之比（Rposterior/Ranterior）、角膜中央厚度（CCT）、角膜总屈光力（Knet）、模拟角膜屈光力（SimK）、角膜前表面屈光力（Kanterior）、角膜后表面屈光力（Kposterior），IOL Master获得的角膜屈光力（Km），临床病史法计算LASIK术后角膜总屈光力（Kchm）。连续测量3次。采用变异系数（CV）、Cronbach′s Alpha系数及组内相关系数（ICC）评估重复性；Bonfferroni校正的多重比较分析SimK、Knet、Km与Kchm之间的差异；Pearson相关分析SimK、Knet、Km与Kchm之间的相关性；Bland-Altman分析SimK与Kchm，Knet与Kchm，Km与Kchm，SimK与Knet，SimK与Km一致性并计算95%一致性界限范围（LoA）。结果Ranterior、Rposterior、Rposterior/Ranterior、Kanterior、Kposterior、SimK、Knet和CCT分别为（8.560±0.292）mm、（6.525±0.159）mm、0.763±0.024、（43.98±1.48）D、（-6.13±0.15）D、（39.47±1.33）D、（37.93±1.42）D和（451.81±33.91）μm，各参数CV均小于1%，各参数Cronbach′s Alpha系数和ICC均大于0.9。SimK比Kchm大（0.434±0.433）D，Knet比Kchm小（1.112±0.471）D，Km比Kchm大（0.334±0.379）D，SimK比Knet大（1.546±0.162）D，差异均有统计学意义（P<0.01）；SimK比Km大（0.100±0.287）D，差异无统计学意义。Pearson相关分析，SimK、Knet、Km、Kchm相互间均具有密切的相关性（r均≥0.944，P<0.01）。Bland-Altman图分析SimK与Kchm，Knet与Kchm，Km与Kchm，SimK与Knet，SimK与Km差值的95%一致性区间分别为-0.41～1.28 D，-2.04～-1.11 D，-0.41～1.08 D，1.23～1.86 D，-0.46～0.66 D。结论 RTVue FD-OCT测量LASIK术后角膜曲率和中央角膜厚度具有良好的重复性；RTVue FD-OCT和IOL Master获得的LASIK术后模拟角膜屈光力比临床病史法获得的理论角膜总屈光力略大0.3～0.4 D；Knet可能是评估LASIK术后角膜屈光力的较准确方法，但用于LASIK术后人工晶状体屈光力的预测，还需进一步的临床研究。

Repeatability and accuracy of corneal parameters in post-LASIK eyes measured by Fourier-domain optical coherence topography

Objective To evaluate the repeatability and accuracy of corneal parameters in post-laser in situ keratomileusis （LASIK） eyes obtained by RTVue Fourier-domain optical coherence topography （FD-OCT）. Methods In this prospective study， 58 right eyes of 58 persons who agreed to undergo LASIK were included. Subjective refractions were performed before LASIK and 3 months after LASIK. IOL Master was used to evaluate corneal power before LASIK. Three months after LASIK， RTVue FD-OCT was used to evaluate the anterior corneal curvature in a 3 mm central zone （Ranterior）， posterior corneal curvature in a 3 mm zone （Rposterior）， the ratio of posterior and anterior curvature （Rposterior/ Ranterior）， central corneal thickness （CCT）， total corneal power （Knet）， simulated corneal power （SimK）， anterior corneal power （Kanterior）， and posterior corneal power （Kposterior）. Km was obtained with IOL Master 3 months after the surgery. Kchm was calculated from the patient′s clinical history. Repeatability of corneal parameters was assessed using the coefficient of variation （CV）， Cronbach′s alpha， and intra-class correlation coefficient （ICC）. Bonferroni corrected multiple comparisons analyzed the differences between SimK， Knet， Km and Kchm. A Pearson correlation analyzed the correlations between SimK， Knet， Km and Kchm. Bland-Altman plots analyzed the agreements between SimK and Kchm， Knet and Kchm， Km and Kchm， SimK and Knet， and SimK and Km. Results The Ranterior， Rposterior， Rposterior/Ranterior， Kanterior， Kposterior， SimK， Knet and CCT were （8.560±0.292）mm， （6.525±0.159）mm， 0.763±0.024， （43.98±1.48）D， （-6.13±0.15）D， （39.47±1.33）D， （37.93±1.42）D and （451.81±33.91）μm， respectively. The CVs of all parameters were lower than 1%. Cronbach′s alpha and ICC were both higher than 0.9. SimK was （0.434±0.433）D higher than Kchm， Knet was （1.112±0.471）D lower than Kchm， Km was （0.334±0.379）D higher than Kchm， and SimK was （1.546±0.162）D higher than Kchm. All the differences were statistically significant （P<0.01）. SimK was （0.100±0.287）D higher than Km but the difference was not statistically significant. There were close correlations among SimK， Knet， Km and Kchm （r≥0.944， P<0.01）. The Bland-Altman analysis showed that the 95% limit of agreements between SimK and Kchm， Knet and Kchm， Km and Kchm， SimK and Knet， and SimK and Km were -0.41～1.28 D， -2.04～-1.11 D， -0.41～1.08 D， 1.23～1.86 D， -0.46～0.66 D， respectively. Conclusion The RTVue Fourier-domain OCT had high repeatability on corneal curvature and CCT measurements in post-LASIK eyes. The SimK obtained by RTVue Fourier-domain OCT and IOL Master were 0.3 to 0.4 D higher than those obtained by clinical history. Knet may be a more accurate method to assess corneal power in post-LASIK eyes， but further clinical studies are needed for the prediction of post-LASIK intraocular lens power.