A-Yong Yu1,2#, Junming Ye1#, Giacomo Savini3 , Yiran Wang1 , Tianjiao Zhang1 , Min Chen1 , Qinmei Wang1,2, Jinhai Huang1,2
1 Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
2 State Key Laboratory of Optometry, Ophthalmology and Vision Science, Wenzhou, China
3 G.B. Bietti Foundation IRCCS, Rome, Italy
Contributions: (I) Conception and design: AY Yu, J Ye, Q Wang, J Huang; (II) Administrative support: Q Wang, J Huang; (III) Provision of study materials or patients: AY Yu, J Ye; (IV) Collection and assembly of data: Y Wang, T Zhang, M Chen; (V) Data analysis and interpretation: AY Yu, G Savini, J Huang; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.
# These authors contributed equally to this work.
Correspondence to: Prof. Qinmei Wang, MD; Jinhai Huang, MD, PhD. Eye Hospital of Wenzhou Medical University, 270 West Xueyuan Road, Wenzhou, China. Email: wqm6@mail.eye.ac.cn; vip999vip@163.com, vip9999vip@wmu.edu.cn.
Background: To assess the intra-observer repeatability and inter-observer reproducibility of central corneal thickness (CCT) and mid-peripheral corneal thickness (MPCT) measurements using a new Scheimpflug imaging instrument (Scansys) and compare the agreement with the rotating Scheimpflug corneal tomographer (Pentacam HR).
Methods: The same well-trained operator performed the measuring using the two devices, after which Scansys measurements were repeated by another operator. Both instruments required three consecutive measurements per subject. Corneal thickness measurements were obtained by each instrument, including CCT, thinnest corneal thickness (TCT), pupil corneal thickness (PCT), and MPCT. Test-retest repeatability (TRT), within-subject coefficient of variation (CoV), and intra-class correlation coefficient (ICC) were used to evaluate repeatability and reproducibility. A paired t-test was used to compare the differences between Scansys and Pentacam, and the agreement was compared with Bland-Altman plots.
Results: This study enrolled 112 healthy subjects. The CoV were <0.91% and 0.55% for repeatability and reproducibility, respectively. The ICC was close to 1 in all measurements. For intra-observer repeatability in the CT2mm region, TRT was <10.30 µm. Moreover, TRT was <15.26 µm within the CT5mm region. The paired t-test showed significant differences in all corneal thickness measurements (P<0.001). The central region and CT2mm agreement were high, but the largest range of 95% limits of agreement (LoA) appeared in the CTnasal-5mm.
Conclusions: The new Scheimpflug imaging instrument showed excellent intra-observer repeatability and inter-observer reproducibility for corneal thickness measurements. The agreement analysis suggested that Scansys and Pentacam could be interchangeably used between the central region and CT2mm, except CT5mm.
