Sheng Huan, Bottjer Carol A, Bullimore Mark A
College of Optometry, The Ohio State University, Columbus 43210-1240, USA.
Optom Vis Sci. 2004 Jan;81(1):27-34. doi: 10.1097/00006324-200401000-00007.
Axial length is traditionally measured using A-scan ultrasound. The IOLMaster is a new instrument that uses partial coherence interferometry to measure axial length. We compared the repeatability of these techniques for both an experienced and an inexperienced observer, the agreement between the two techniques, and the effect of cycloplegia on IOLMaster measurements.
Five measurements of axial length and three measurements of anterior chamber depth were taken with the IOLMaster in two sessions separated by 1 to 12 days in 20 young adults. The two examiners each took measurements, and the subject was then cyclopleged with 1% tropicamide. The IOLMaster readings were then repeated by both examiners, followed by five ultrasound readings. Repeatability was evaluated by calculating the difference between measurements from the two sessions. The mean and standard deviation of these differences was then used to determine the 95% limits of agreement (LoA) for each technique. In addition, the agreement between the IOLMaster and ultrasound was assessed, along with the effect of cycloplegia on IOLMaster readings.
The IOLMaster was more repeatable than ultrasound. For axial length, the 95% LoA were -0.11 to +0.07 mm, -0.06 to +0.05 mm, and -0.25 to +0.35 mm, for noncycloplegic IOLMaster, cycloplegic IOLMaster, and ultrasound, respectively. The two instruments showed modest agreement with each other (mean difference, +0.12 mm; 95% LoA, -0.39 to +0.64 mm; p > 0.0125). Cycloplegia had no significant effect on IOLMaster axial length measurements. The 95% LoA for anterior chamber depth measurement were -0.11 to +0.18 mm, -0.06 to +0.04 mm, and -0.19 to +0.21 mm, for noncycloplegic IOLMaster, cycloplegic IOLMaster, and ultrasound, respectively. The IOLMaster gave significantly longer anterior chamber depths than ultrasound (mean, +0.18 mm; 95% LoA, -0.02 to +0.37 mm; p < 0.0125), and cycloplegia produced significantly deeper anterior chamber depths using the IOLMaster (mean, +0.12 +/- 0.09 mm; 95% LoA, -0.05 to +0.29 mm; t = 6.17; p < 0.001). The experienced observer's measurements were more repeatable than the inexperienced observer's for ultrasound, but not for the IOLMaster.
The superior repeatability of the IOLMaster suggests that it should become the standard for axial length measurement. The 95% limits of agreement for the cycloplegic measurements correspond to a change in refractive error of +/-0.12 D.
传统上使用A超测量眼轴长度。IOLMaster是一种使用部分相干干涉测量法来测量眼轴长度的新仪器。我们比较了经验丰富和缺乏经验的观察者使用这两种技术测量的可重复性、两种技术之间的一致性以及睫状肌麻痹对IOLMaster测量结果的影响。
20名年轻成年人在相隔1至12天的两个时间段内，使用IOLMaster进行5次眼轴长度测量和3次前房深度测量。两位检查者分别进行测量，然后用1%托吡卡胺对受试者进行睫状肌麻痹。之后两位检查者再次进行IOLMaster读数，接着进行5次超声测量。通过计算两个时间段测量值之间的差异来评估可重复性。然后使用这些差异的平均值和标准差来确定每种技术的95%一致性界限（LoA）。此外，评估了IOLMaster与超声之间的一致性以及睫状肌麻痹对IOLMaster读数的影响。
IOLMaster比超声更具可重复性。对于眼轴长度，非睫状肌麻痹状态下IOLMaster测量的95% LoA为 -0.11至 +0.07 mm，睫状肌麻痹状态下IOLMaster测量的为 -0.06至 +0.05 mm，超声测量的为 -0.25至 +0.35 mm。两种仪器之间显示出适度的一致性（平均差异，+0.12 mm；95% LoA，-0.3至 +0.64 mm；p > 0.0125）。睫状肌麻痹对IOLMaster眼轴长度测量没有显著影响。对于前房深度测量，非睫状肌麻痹状态下IOLMaster测量的95% LoA为 -0.11至 +0.18 mm，睫状肌麻痹状态下IOLMaster测量 的为 -0.06至 +0.04 mm，超声测量的为 -0.19至 +0.21 mm。IOLMaster测量的前房深度比超声测量的显著更长（平均值，+0.18 mm；95% LoA，-0.02至 +0.37 mm；p < 0.0125），并且使用IOLMaster时睫状肌麻痹使前房深度显著更深（平均值，+0.12±0.09 mm；95% LoA，-0.05至 +0.29 mm；t =6.17；p < 0.001）。对于超声测量，经验丰富的观察者的测量比缺乏经验的观察者更具可重复性，但对于IOLMaster测量则不然。
IOLMaster卓越的可重复性表明它应成为眼轴长度测量的标准。睫状肌麻痹测量的95%一致性界限对应于±0.12 D的屈光不正变化。
