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. 2022 Mar 19;12(3):754.
doi: 10.3390/diagnostics12030754.

Comparison of Mean Corneal Power of Annular Rings and Zones Using Swept-Source Optical Coherence Tomography

Jing Dong  1 , Jinhan Yao  2 , Shuimiao Chang  2 , Piotr Kanclerz  3   4 , Ramin Khoramnia  5 , Xiaogang Wang  2
Affiliations

Comparison of Mean Corneal Power of Annular Rings and Zones Using Swept-Source Optical Coherence Tomography

Jing Dong et al. Diagnostics (Basel). .

Abstract

This study aims to investigate differences in the mean corneal power of annular zones (corneal power measured over the inner annular zone of difference diameters) and rings (corneal power measured over a ring of different diameters) centered on the corneal apex using the swept-source optical coherence tomography technique. The mean anterior axial curvature (AAC), posterior axial curvature (PAC), and total corneal power (TCP) centered on the corneal apex with the annular rings (0−2 mm, 2−4 mm, 4−6 mm, and 6−8 mm) and zones were assessed using the ANTERION device. The paired-sample t-test was used for data comparison. For the 0−2 mm comparison, the AAC, PAC, and TCP values of rings and zones were interchangeable. For the 2−4 mm comparison, the AAC of the rings was lower than that of the zones (p = 0.004), and the TCP values of the rings were higher than that of the zones (p < 0.001). For the 4−6 mm comparison, the AAC of the rings was lower than that of the zones (p < 0.001), and the PAC and TCP values of the rings were higher than that of the zones (both p < 0.001). For the 6−8 mm comparison, the AAC of the rings was lower than that of the zones (p < 0.001), and the PAC and TCP values of the rings were higher than that of the zones (both p < 0.001). Comparisons between AAC and TCP in each sub-region showed significant differences both in the rings (p < 0.001) and the zones (p < 0.008). Differences in the AAC, PAC, and TCP measured at different diameters (2−4 mm, 4−6 mm, and 6−8 mm) of the rings and zones, centered on the corneal apex, should be noticed in clinical practice. As the diameter increases, the difference between the rings and the zones in terms of AAC, PAC, and TCP increase as well. Clinicians should also pay attention to differences between AAC and TCP for the rings and the zones within the same annular region.

Keywords: anterior axial curvature; posterior axial curvature; rings; total cornea power; zones.

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Conflict of interest statement

There are no conflict of interest to declare.

Figures

Figure 1
Figure 1
The cross-sectional image and corresponding ocular tissue information of anterior segment and corresponding scanning directions on the eye image using ANTERION device. The central 8 mm-diameter cornea area centered on corneal vertex based on 65 radial scanning lines was used for corneal curvature analysis.
Figure 2
Figure 2
The anterior axial curvature, posterior corneal curvature, and total corneal power changes with different ring and zone diameters centered on the corneal vertex for a right eye. The first row was segmented by different diameter zones, and the second row was segmented by different diameter rings. The red and blue lines represent the meridian of steep and flat corneal curvature, respectively.
Figure 3
Figure 3
Box and whisker plot of the anterior axial curvature (a), posterior axial curvature (b), and total corneal power (c) changes with different rings and zones diameters centered on the corneal apex.
Figure 4
Figure 4
Box and whisker plot of AAC and TCP difference for rings and zones in different annular regions.
See this image and copyright information in PMC

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