Comparison of Central Corneal Thickness Measurements between Noncontact Specular Microscopy and Ultrasound Pachymetry

Kyoung Ohn; Mee Yon Lee; Young Chun Lee; Hye Young Shin

doi:10.3341/jkos.2019.60.7.635

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Ohn, Lee, Lee, and Shin: Comparison of Central Corneal Thickness Measurements between Noncontact Specular Microscopy and Ultrasound Pachymetry

Original Article

Journal of the Korean Ophthalmological Society 2019; 60(7): 635-642.

Published online: 15 July 2019

DOI: https://doi.org/10.3341/jkos.2019.60.7.635

Comparison of Central Corneal Thickness Measurements between Noncontact Specular Microscopy and Ultrasound Pachymetry

Kyoung Ohn, MD, Mee Yon Lee, MD, PhD, Young Chun Lee, MD, PhD, Hye Young Shin, MD, PhD

Department of Ophthalmology, Uijeongbu St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Uijeongbu, Korea.

Address reprint requests to Hye Young Shin, MD, PhD. Department of Ophthalmology, Uijeongbu St. Mary's Hospital, #271 Cheonbo-ro, Uijeongbu 11765, Korea. Tel: 82-31-820-3022, Fax: 82-31-847-3418, Antares78@empas.com

Received 14 February 2019 Revised 23 March 2019 Accepted 25 June 2019

The Korean Ophthalmological Society

(open-access):

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

We compared and analyzed central corneal thickness (CCT) measurements according to the corneal thickness obtained with noncontact specular microscopy (NCSM) and ultrasound pachymetry (USP).

Methods

CCT was measured in the order of NCSM and USP by a single optometrist in 120 eyes of 120 healthy subjects. The measurements were compared between the devices and the measurement agreements and correlations between the devices were analyzed. To determine if the measurements differed depending on the thickness of the cornea, the patients were divided into three tertile groups from the thinnest patient by CCT measurement using USP, and then the differences in CCT measured by the two devices were analyzed.

Results

The CCT measurements using NCSM and USP were 548.25 ± 4.64 µm and 533.09 ± 35.96 µm, respectively. NCSM measurements were found to be thicker, showing statistically significant differences between the measurements (p < 0.001). The two examinations showed a high degree of correlation (r = 0.878; p < 0.01). In the three groups, the differences in CCT measurements between NCSM and USP were 12.93 ± 21.88 µm, 16.85 ± 15.89 µm, and 15.70 ± 20.46 µm, respectively, but the differences between the three groups were not statistically significant (p = 0.655).

Conclusions

Our results show that although the differences in CCT measurements using NCSM and USP were consistent regardless of the corneal thickness, the CCT measurements by NCSM and USP were highly correlated.

Keywords: Central corneal thickness, Endothelial cell density, Noncontact specular microscopy, Ultrasound pachymetry

Figures and Tables

Figure 1

Bland Altman plots between the 2 methods. The middle line is the mean and the lines on the side represent the upper and lower 95% limits of agreement. NCSM = noncontact specular microscopy; USP = ultrasound pachymetry; SD = standard deviation.

Figure 2

Correlation analysis graph (scatter plot) between the 2 methods. Scatter gram showing the correlation of central corneal thickness measured by USP and NCSM. USP = ultrasound pachymetry; NCSM = noncontact specular microscopy.

Table 1

Study variables grouped by central corneal thickness

Values are presented as mean ± standard deviation unless otherwise indicated.

CCT = central corneal thickness; USP = ultrasound pachymetry; NCSM = noncontact specular microscopy; ΔCCT = NCSM-USP.

^*One-way analysis of variance test.

Notes

^{Conflicts of Interest} The authors have no conflicts to disclose.

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