Corneal Higher-Order Aberrations Measurements: Precision of SD-OCT/Placido Topography and Comparison with a Scheimpflug/Placido Topography in Eyes After Small-Incision Lenticule Extraction

Abstract

Introduction: The aim of this study was to evaluate the measurements of corneal higher-order aberrations (HOAs) obtained by a new anterior segment optical coherence tomography (OCT) technique combined with a Placido topographer (the MS-39 device) in eyes with prior small-incision lenticule extraction (SMILE) and compare them to the measurements obtained by a Scheimpflug camera combined with a Placido topographer (the Sirius device).

Methods: A total of 56 eyes (56 patients) were included in this prospective study. Corneal aberrations were analyzed for the anterior, posterior, and total cornea surfaces. Within-subject standard deviation (Sw), test-retest repeatability (TRT), and intraclass correlation coefficient (ICC) were used to assess the intraobserver repeatability and interobserver reproducibility. The differences were evaluated by paired t-test. Bland-Altman plots and 95% limits of agreement (95% LoA) were used to evaluate the agreement.

Results: High repeatability was observed for anterior and total corneal parameters, with Sw value < 0.07, TRT ≤ 0.16, and ICCs > 0.893, but not trefoil. For the posterior corneal parameters, ICCs varied from 0.088 to 0.966. Regarding interobserver reproducibility, all Sw values were ≤ 0.04 and TRT ≤ 0.11. ICCs ranged from 0.846 to 0.989, from 0.432 to 0.972, and from 0.798 to 0.985 for the anterior, total, and posterior corneal aberrations parameters, respectively. The mean difference in all aberrations was ≤ 0.05 μm. All parameters showed a narrow 95% LoA.

Conclusion: The MS-39 device achieved high precision in both anterior and total corneal measurements; the precision of posterior corneal higher-order RMS, astigmatism II, coma, and trefoil was lower. The two technologies used by the MS-39 and Sirius devices can be used interchangeably for measuring corneal HOAs after SMILE.

Keywords: Agreement; Higher-order aberrations; Optical coherence tomography-Placido; Small-incision lenticule extraction.

Conflict of interest statement

Rui Ning, Xiaomin Huang, Yili Jin, Chak Seng Lei, Xindi Ma, Shuoyu Xu, Jinxuan Xiahou, Giacomo Savini, Domenico Schiano-Lomoriello, Xiaoying Wang, Xingtao Zhou, and Jinhai Huang have nothing to disclose.

© 2023. The Author(s).

Figures

Fig. 1

Violin plots between measurements by the MS-39 and Sirius devices in terms of total, anterior, and posterior corneal aberrations. The area represents the probability of distribution around a value. The top and bottom black dotted lines represent the interquartile range, while the middle black line is the median limbus. Statistical comparison between two devices was performed using paired t test. Asterisks indicate a significant difference at *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001; ns, not significant p > 0.05

Fig. 2

Bland–Altman plot of the total RMS and higher-order root mean square (RMS) for the MS-39 and Sirius devices in terms of total, anterior, and posterior corneal aberrations. The solid line represents the mean difference. The dotted lines represent the upper and lower 95% limits of agreement (LoAs). Z Zernike

Fig. 3

Bland–Altman plot of the coma and trefoil for the MS-39 and Sirius devices in terms of total, anterior, and posterior corneal aberrations. The solid line represents the mean difference. The dotted lines represent the upper and lower 95% LoAs. Z Zernike

Fig. 4

Bland–Altman plot of the spherical aberration and astigmatism II for the MS-39 and Sirius devices in terms of total, anterior, and posterior corneal aberrations. The solid line represents the mean difference. The dotted lines on the side represent the upper and lower 95% LoAs. Ast Astigmatism, SA spherical aberration, Z Zernike