Agreement and repeatability of central corneal thickness measurements by four different optical devices and an ultrasound pachymeter
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To compare the repeatability and agreement of central corneal thickness (CCT) measurements by spectral-domain optical coherence tomography (OCT), corneal topography (CT) with a combined Scheimpflug–Placido system, optical biometry (OB), specular microscopy (SM), and ultrasound pachymetry (UP).
A single observer measured CCT twice in 150 eyes of 150 subjects with each of five devices: Nidek RS-3000 Advance OCT, CSO Sirius combined Scheimpflug–Placido disc system CT, Nidek AL-Scan partial coherence interferometry-based OB, Tomey EM-3000 SM, and Reichert iPac ultrasonic pachymeter. Pachymetry values corrected by the SM device software were also recorded. Levels of agreement between devices were evaluated by Bland–Altman plots with 95% limits of agreement, and repeatability for each device was analysed with intraclass correlation coefficients.
The mean CCTs measured by OCT, CT, OB, SM, corrected SM, and UP were 544.60 ± 29.56, 536.19 ± 32.14, 528.29 ± 29.45, 524.88 ± 32.38, 537.88 ± 32.38, and 545.29 ± 30.75 μm, respectively. Mean CCT differed significantly between the devices (p < 0.05) apart from between OCT and UP, and between CT and corrected SM. Mean paired differences between devices ranged between 0.68 and 20.41 μm. Repeatability with all devices was excellent (> 0.99). The range of limits of agreement was the least between OCT and UP.
Different CCT measurement techniques produce quite different results, so CCT evaluation and follow-up should be performed using the same device or devices with close compatibility.
KeywordsCentral corneal thickness Corneal topography Optical coherence tomography Optic biometry Specular microscopy Ultrasonic pachymeter
This research received no grant from any funding agency in the public, commercial or not-for-profit sectors.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest
All procedures performed in this study were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The ethical approval was obtained from Kırıkkale University Clinical Research Ethical Committee, Date: 10.11.2015, Number: 25/08.
Informed consent was obtained from all individual participants included in the study.