Chalkiadaki Evangelia, Gartaganis Panos S, Ntravalias Thomas, Giannakis Ioannis, Manousakis Evangelos, Karmiris Efthymios
Department of Ophthalmology, 251 Hellenic Airforce General Hospital, Hpeirou 36, Agia Paraskeyi 15341, Greece.
Department of Ophthalmology, 251 Hellenic Airforce General Hospital, Athens, Greece.
Ther Adv Ophthalmol. 2022 Mar 31;14:25158414211063283. doi: 10.1177/25158414211063283. eCollection 2022 Jan-Dec.
Cataract surgery in keratoconic patients is challenging because of the corneal distortion, which can lead to inaccurate keratometry readings. This study is a comparison of the accuracy of keratometry readings by two types of devices in a tertiary hospital.
To evaluate the comparability of corneal power measurements, anterior chamber depth (ACD), and white-to-white (WTW) distance between Scheimpflug-based tomography (Pentacam AXL; OCULUS GmbH, Wetzlar, Germany) and swept-source optical biometry (IOLMaster 700; Carl Zeiss Meditec AG, Jena, Germany) in patients with keratoconus.
This pilot, prospective, interinstrument reliability study included 30 keratoconic eyes of 15 individuals who had not undergone any kind of corneal surgery. Standard K and total refractive power (TK) of the flattest and steepest axes of the IOLMaster 700 were compared with the standard keratometry (SimK), true net power (TNP), equivalent keratometer readings (EKR), and total corneal refractive power (TCRP) of the Pentacam. The Bland-Altman analysis was used to evaluate the agreement between the measurements of both devices. The paired-samples -test and the Wilcoxon signed-rank test were performed to compare the mean values of the variables obtained with the devices.
The K1 value of the IOLMaster 700 was significantly higher from EKR K1 along the 3-mm (mean difference: 0.79 diopters, = 0.01), 4-mm (mean difference: 1.01 D, = 0.01), and 4.5-mm zones (mean difference: 1.20 D, = 0.01) and TNP K1 along the 3-mm (mean difference: 0.88 D, < 0.001) and 4-mm zones (mean difference: 0.97 D, < 0.001). The TK1 value was significantly higher from EKR K1 along the 2-mm (mean difference: 0.42 D, = 0.04), 3-mm (mean difference: 0.83 D, = 0.003), 4-mm (mean difference: 1.05 D, = 0.004), and 4.5-mm zones (mean difference: 1.24 D, = 0.005) and TNP K1 along the 3-mm (mean difference: 0.92 D, < 0.001) and 4-mm zones (mean difference: 1.01 D, < 0.001). The K2 value of the IOLMaster 700 was significantly higher from TK2 (mean difference: 0.11 D, = 0.04) and all the corresponding variables of the Pentacam device. The TK2 value was significantly higher from all the corresponding variables of the Pentacam device. The Pentacam also yielded significantly lower values for the WTW distance (mean difference: 0.31 mm, < 0.001) and no significant difference in terms of ACD values ( = 0.9).
The IOLMaster measured significantly greater keratometry readings in the steep axis for all the variables studied. The keratometry and WTW measurements of the investigated devices cannot be used interchangeably in keratoconus.
圆锥角膜患者的白内障手术具有挑战性，因为角膜变形会导致角膜曲率计读数不准确。本研究是在一家三级医院中对两种类型设备的角膜曲率计读数准确性进行比较。
评估基于Scheimpflug的断层扫描（Pentacam AXL；德国韦茨拉尔OCULUS GmbH公司）和扫频光学生物测量仪（IOLMaster 700；德国耶拿卡尔蔡司医疗技术公司）在圆锥角膜患者中测量角膜屈光力、前房深度（ACD）和白对白（WTW）距离的可比性。
这项前瞻性、仪器间可靠性的试点研究纳入了15名未接受过任何角膜手术的个体的30只圆锥角膜眼。将IOLMaster 700最平轴和最陡轴的标准角膜曲率（K）和总屈光力（TK）与Pentacam的标准角膜曲率计读数（SimK）、真实净屈光力（TNP）、等效角膜曲率计读数（EKR）和总角膜屈光力（TCRP）进行比较。采用Bland-Altman分析评估两种设备测量结果之间的一致性。进行配对样本t检验和Wilcoxon符号秩检验以比较两种设备获得的变量均值。
IOLMaster 700的K1值在3毫米（平均差值：0.79屈光度，P = 0.01）、4毫米（平均差值：1.01 D，P = 0.01）和4.5毫米区域（平均差值：1.20 D，P = 0.01）与EKR K1相比显著更高，在3毫米（平均差值：0.88 D，P < 0.001）和4毫米区域（平均差值：0.97 D，P < 0.001）与TNP K1相比显著更高。TK1值在2毫米（平均差值：0.42 D，P = 0.04）、3毫米（平均差值：0.83 D，P = 0.003）、4毫米（平均差值：1.05 D，P = 0.004）和4.5毫米区域（平均差值：1.24 D，P = 0.005）与EKR K1相比显著更高，在3毫米（平均差值：0.92 D，P < 0.001）和4毫米区域（平均差值：1.01 D，P < 0.001）与TNP K1相比显著更高。IOLMaster 700的K2值与TK2（平均差值：0.11 D，P = 0.04）以及Pentacam设备的所有相应变量相比显著更高。TK2值与Pentacam设备的所有相应变量相比显著更高。Pentacam测得的WTW距离值也显著更低（平均差值：0.31毫米，P < 0.001），而ACD值无显著差异（P = 0.9）。
对于所有研究变量，IOLMaster在陡轴上测得的角膜曲率计读数显著更高。在圆锥角膜中，所研究设备的角膜曲率计和WTW测量结果不能互换使用。
