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Shin, Jeong, Kim, Kim, Lee, Kim, and Kim: Comparison of Central Corneal Thickness Measured by Swept-source Optical Coherence Tomography and Ultrasound Pachymetry
Original Article

Journal of the Korean Ophthalmological Society 2017; 58(3): 276-282.

Published online: 15 March 2017

DOI: https://doi.org/10.3341/jkos.2017.58.3.276

Comparison of Central Corneal Thickness Measured by Swept-source Optical Coherence Tomography and Ultrasound Pachymetry

Woo Beom Shin, MD1, 2, Hyun Kyo Jeong, MD1, 2, Min Kyo Kim, MD1, 2, Hong Seok Kim, MD1, Jun Mo Lee, MD1, Chan Yun Kim, MD2, Ji Hyun Kim, MD1

1Siloam Eye Hospital, Seoul, Korea.

2The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.

Address reprint requests to Ji Hyun Kim, MD. Siloam Eye Hospital, #181 Deungchon-ro, Gangseo-gu, Seoul 07668, Korea. Tel: 82-2-2650-0880, Fax: 82-2-2650-0725, jhkim@siloam.co.kr

Received 3 November 2016       Revised 30 January 2017       Accepted 26 February 2017

©2017 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

To analyze and compare ultrasound pachymetry (USP) with a more recently adopted device, the intra ocular lens (IOL) master 700, which are both used to measure central corneal thickness.

Methods

The central corneal thickness was measured in 24 eyes of 12 glaucoma patients and in 83 eyes of 42 normal patients. First, the IOL master 700 was used to measure the central corneal thickness, followed by measurements taken using USP later. The results were analyzed using a paired t-test. We analyzed the agreement and the correlations between the two test devices by using Bland-Altman plots and the Pearson correlation test. To evaluate the reproducibility, measurements with the IOL master 700 were taken twice for a few normal patients within a small time interval.

Results

Via the IOL master 700, the thickness of the central cornea showed a high reproducibility and repeatability, demonstrating 2.7 ± 1.7 µm for the test-retest variability, 6.78% for the coefficient of variation, and 0.997 for the intraclass correlation value. The mean measurements using USP and the IOL master 700 are 554.4 ± 37.4 µm and 551.1 ± 37.1 µm, respectively, showing that the IOL master 700 measured significantly smaller values than USP with a p-value < 0.001. The deviations between the two methods are scattered throughout the 95% confidence interval. According to the Pearson correlation test, the measured values of the two test devices were found to have a highly positive correlation (r = 0.977, p < 0.0001).

Conclusions

This study demonstrated that the central corneal thickness (CCT) measured via the IOL master was significantly thinner than that of USP, and the two test devices had a high correlation and good agreement. The CCT value measured via the IOL master 700 also exhibited high reproducibility.

Keywords: Central corneal thickness, Ultrasound pachymetry, IOL master 700

Figures and Tables

Figure 1

Bland Altman plots between the 2 methods. The middleline is the mean and the lines on the side represent the upper and lower 95% limits of agreement. USP = ultrasound pachymetry; IOL = intraocular lens; SD = standard deviation.

jkos-58-276-g001
Figure 2

Correlation analysis graph (Scatter plot) between the 2 methods. Scattergram showing the correlation of central corneal thickness measured by USP and IOL master 700. USP = ultrasound pachymetry; IOL = intraocular lens.

jkos-58-276-g002
Table 1

Intraclass correlation coefficient, coefficient of variation, and test–retest variability of central corneal thickness measurements with IOL master 700 in healthy eyes

jkos-58-276-i001

Values are presented as mean ± SD unless otherwise indicated.

ICC = intraclass correlation; CI = confidence interval; CV = coefficient of variation; CCT = central corneal thickness.

Table 2

Study variables and central corneal thickness of glaucoma patients (group 1) and normal patients (group 2)

jkos-58-276-i002

Values are presented as mean ± SD unless otherwise indicated.

CCT = central corneal thickness; USP = ultrasound pachymetry.

Table 3

Central corneal thickness measurement with USP and IOL master 700 in glaucomatous and healthy eyes

jkos-58-276-i003

Values are presented as mean ± SD unless otherwise indicated.

USP = ultrasound pachymetry.

Table 4

Difference of central corneal thickness in glaucomatous and healthy eyes

jkos-58-276-i004

Values are presented as mean ± SD unless otherwise indicated.

ΔCCT = ultrasound pachymetry (USP)-IOL master 700; CCT = central corneal thickness.

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