Yap Timothy E, Archer Timothy J, Gobbe Marine, Reinstein Dan Z
J Refract Surg. 2016 Feb;32(2):110-6. doi: 10.3928/1081597X-20151223-01.
To compare corneal thickness measurements between three imaging systems.
In this retrospective study of 81 virgin and 58 post-laser refractive surgery corneas, central and minimum corneal thickness were measured using optical coherence tomography (OCT), very high-frequency digital ultrasound (VHF digital ultrasound), and a Scheimpflug imaging system. Agreement between methods was analyzed using mean differences (bias) (OCT - VHF digital ultrasound, OCT - Scheimpflug, VHF digital ultrasound - Scheimpflug) and Bland-Altman analysis with 95% limits of agreement (LoA).
Virgin cornea mean central corneal thickness was 508.3 ± 33.2 µm (range: 434 to 588 µm) for OCT, 512.7 ± 32.2 µm (range: 440 to 587 µm) for VHF digital ultrasound, and 530.2 ± 32.6 µm (range: 463 to 612 µm) for Scheimpflug imaging. OCT and VHF digital ultrasound showed the closest agreement with a bias of -4.37 µm, 95% LoA ±12.6 µm. Least agreement was between OCT and Scheimpflug imaging with a bias of -21.9 µm, 95% LoA ±20.7 µm. Bias between VHF digital ultrasound and Scheimpflug imaging was -17.5 µm, 95% LoA ±19.0 µm. In post-laser refractive surgery corneas, mean central corneal thickness was 417.9 ± 47.1 µm (range: 342 to 557 µm) for OCT, 426.3 ± 47.1 µm (range: 363 to 563 µm) for VHF digital ultrasound, and 437.0 ± 48.5 µm (range: 359 to 571 µm) for Scheimpflug imaging. Closest agreement was between OCT and VHF digital ultrasound with a bias of -8.45 µm, 95% LoA ±13.2 µm. Least agreement was between OCT and Scheimpflug imaging with a bias of -19.2 µm, 95% LoA ±19.2 µm. Bias between VHF digital ultrasound and Scheimpflug imaging was -10.7 µm, 95% LoA ±20.0 µm. No relationship was observed between difference in central corneal thickness measurements and mean central corneal thickness. Results were similar for minimum corneal thickness.
Central and minimum corneal thickness was measured thinnest by OCT and thickest by Scheimpflug imaging in both groups. A clinically significant bias existed between Scheimpflug imaging and the other two modalities.
比较三种成像系统测量的角膜厚度。
在这项回顾性研究中，对81只未接受激光屈光手术的角膜和58只接受过激光屈光手术的角膜，使用光学相干断层扫描（OCT）、甚高频数字超声（VHF数字超声）和Scheimpflug成像系统测量中央角膜厚度和最小角膜厚度。使用平均差异（偏差）（OCT-VHF数字超声、OCT-Scheimpflug、VHF数字超声-Scheimpflug）和具有95%一致性界限（LoA）的Bland-Altman分析来分析方法之间的一致性。
在未接受激光屈光手术的角膜中，OCT测量的中央角膜平均厚度为508.3±33.2µm（范围：434至588µm），VHF数字超声测量的为512.7±32.2µm（范围：440至587µm），Scheimpflug成像测量的为530.2±32.6µm（范围：463至612µm）。OCT和VHF数字超声显示出最接近的一致性，偏差为-4.37µm，95%LoA为±12.6µm。OCT和Scheimpflug成像之间的一致性最差，偏差为-21.9µm，95%LoA为±20.7µm。VHF数字超声和Scheimpflug成像之间的偏差为-17.5µm，95%LoA为±19.0µm。在接受过激光屈光手术的角膜中，OCT测量的中央角膜平均厚度为417.9±47.1µm（范围：342至557µm），VHF数字超声测量的为426.3±47.1µm（范围：363至563µm），Scheimpflug成像测量的为437.0±48.5µm（范围：359至571µm）。OCT和VHF数字超声之间的一致性最接近，偏差为-8.45µm，95%LoA为±13.2µm。OCT和Scheimpflug成像之间的一致性最差，偏差为-19.2µm，95%LoA为±19.2µm。VHF数字超声和Scheimpflug成像之间的偏差为-10.7µm，95%LoA为±20.0µm。未观察到中央角膜厚度测量差异与中央角膜平均厚度之间的关系。最小角膜厚度的结果相似。
在两组中，OCT测量的中央角膜厚度和最小角膜厚度最薄，Scheimpflug成像测量的最厚。Scheimpflug成像与其他两种方法之间存在具有临床意义的偏差。
