LASIK手术前后IOLMaster、OrbscanⅡ及超声法测量角膜曲率、前房深度及眼轴长度的比较

Comparison of corneal curvature, anterior chamber depth and axial length measured by IOLMaster, Orbscan ±Ⅱ and ultrasound before and after LASIK

背景角膜曲率、前房深度、眼轴长度的精确测量对人工晶状体（IOL）度数的计算至关重要，不同方法的测量结果可能对IOL度数的计算结果产生误差。目的比较光学相干生物测量仪（IOLMaster）、OrbscanⅡ眼前节分析仪（OrbscanⅡ）以及A型超声法测量近视患者准分子激光角膜原位磨镶术（LASIK）手术前后角膜曲率（K）、前房深度以及眼轴长度的结果。方法收集近视患者65例130眼，对LASIK手术前及手术后1个月随访到的28例56眼分别行IOLMaster、OrbscanⅡ以及A型超声法眼部生物测量，并对其结果进行比较。结果LASIK手术前，IOLMaster和OrbscanⅡ测量角膜K值分别为（43．32±1．52）D和（42．99±1．45）D，二者相差（0．33±O．03）D，差异有统计学意义（t=10．380，P=0．000）。手术后K值分别为（39．02±2．14）D和（38．91±2．04）D，二者相差（0．12±0．33）D，差异有统计学意义（t=2．715，P=0．009）。Bland—Ahman分析显示，2种方法测量K值的一致性较差。手术前IOLMaster、OrbscanⅡ和A型超声法测得前房深度分别为（3．72＋0．22）、（3．69±0．22）、（3．75±0．27）mm，差异无统计学意义（P=0．100）。A型超声法测量眼轴长度为（25．22±O．99）mm，IOLMaster测得长度为（25．59±1．01）mm，二者相差（-0．37±0．30）mm，差异有统计学意义（t=-14．098，P=0．000），Pearson相关性分析显示二者呈正相关（r=0．954，P=0．000）。手术前后IOLMaster测量眼轴长度分别为（25．54±1．05）mm和（25．48±1．01）mm，二者相差（0．052±0．412）mm，差异无统计学意义（t=0．946，P=0．348）。结论IOLMaster测量角膜曲率与OrbscanⅡ测量结果差别较大，临床上二者不可替代。IOLMaster与OrbscanⅡ测量前房深度结果一致性较好，临床上可替代使用。与A型超声法比较，IOLMaster测得的眼轴长度较长，临床应用要引起注意。

Background It is important to measure the corneal curvature, anterior chamber depth （ACD） and axial length accurately for calculating IOL power. The interchange outcomes from different measuring methods and apparatus will cause unreliable IOL power. Objective The present study was to compare the differences of corneal curvature, anterior chamber depth （ACD） measured by IOLMaster and Orbscan Ⅱ before and after laser in situ keratomileusis（LASIK） and further compare the axial length measured by IOLMaster and A-ultrasound. Methods One hundred and thirty eyes from 65 consecutive myopic patients before LASIK and 56 eyes of 28 cases with 1-month follow-up duration after LASIK in Henan Eye Institute were enrolled in this study. The K value, ACD between IOLMaster and Orbscan Ⅱ as well as results of axial length between IOLMaster and A-ultrasound were compared by using paired t test. The agreements of the measured values among IOLMaster, Orbscan Ⅱ and A-ultrasound were evaluated using Bland-Altman plot. Results Before LASIK,the K value measured by IOLMaster, Orbscan Ⅱ were （ 43.32 ± 1.52 ） D and （42.99 ± 1.45 ） D respectively with the difference value of（ 0.33 ±0.03 ） D, showing a significant difference （ t = 10. 380, P = 0. 000 ） and a positive relation between them （ r = 0.971, P = 0. 000 ）. After LASIK, the K value measured by IOLMaster, Orbscan Ⅱ were（39.02±2. 14）D and （38.91±2.04）D with the difference value （0. 12±0. 33） D, presenting a significant differences between them （ t = 2. 715, P = 0. 009 ）. Bland-Altman plots indicated the disagreement in K value and uninterchangeable. Before LASIK, the ACD measured by IOLMaster,Orbscan Ⅱ and A-ultrasound were （ 3.72 ± 0. 22 ） mm, （ 3.69 ± 0.22 ）mm and （ 3.75 ± 0.27 ） mm respectively and no significant differences were found between them （P 〉 0. 05 ）. Axial length measured by IOLMaster significantly prolonged in comparison with A-uhrasound（25. 59±1. 01 mm vs 25.22±0.99 mm） , and the difference was（ -0.37± 0.30 ） mm, showing significant difference （ t = - 14. 098, P = 0. 000 ） and positive correlation （ r = 0. 954, P = 0. 000 ）. Axial length values measured by IOLMaster were （25.54 ± 1.05 ）mm in preoperation and （ 25.48 ± 1.01 ）mm in postoperation with the difference （0.052±0.412）mm, showing statistically insignificant difference between them （ t = 0. 946,P = 0. 348 ）. Conclusions Keratometries measured by IOLMaster, Orbscan Ⅱ are much more different. Therefore,these two methods are not recommended to use interchangely. ACD measured by IOLMaster,Orbscan Ⅱ and A ultrasound are proved to obtain the similar results and is clinically interchange. Axial length measured by IOLMaster is longer than that measured by A-ultrasound.