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Repeatability of Corneal Epithelial Thickness Measurements Using Fourier-Domain Optical Coherence Tomography in Normal and Post-LASIK Eyes

Ma, Xingxuan Jack; Wang, Li MD, PhD; Koch, Douglas D. MD

doi: 10.1097/ICO.0b013e3182a7f39d
Clinical Science

Purpose: To evaluate the repeatability of corneal epithelial thickness (ET) and corneal thickness (CT) measurements in normal eyes and laser in situ keratomileusis (LASIK)-treated eyes using optical coherence tomography (RTVue system).

Methods: In 35 right eyes of 35 normal subjects and 45 right eyes of 45 subjects who underwent a myopic LASIK, corneal ET and CT were evaluated in 17 areas: (1) 1 central zone within a 0- to 2.0-mm diameter, (2) 8 paracentral zones from a 2.0- to 5.0-mm diameter, and (3) 8 peripheral zones from a 5.0- to 6.0-mm diameter. The repeatability was assessed using within-subject standard deviation (SD), coefficient of variation, and intraclass correlation coefficient.

Results: At the central and paracentral zones, respectively, the SD values were 0.7 μm and 0.6 to 0.9 μm in normal eyes and 0.7 μm and 0.8 to 1.7 μm in LASIK-treated eyes for ET, and 1.0 μm and 2.8 to 4.6 μm in normal eyes and 1.3 μm and 4.0 to 4.8 μm in LASIK-treated eyes for CT. At the peripheral zones, in normal and LASIK-treated eyes, respectively, the SD values ranged from 0.8 to 1.2 μm and 1.4 to 2.2 μm for ET, and 4.1 to 6.4 μm and 6.0 to 9.1 μm for CT. The coefficient of variation values were low and intraclass correlation coefficient values were high in both groups for both ET and CT measurements.

Conclusions: The Optical coherence tomography produced excellent repeatability, especially at the central and paracentral zones up to a 5-mm diameter for both corneal ET and CT measurements.

Supplemental Digital Content is Available in the Text.

Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, TX.

Reprints: Douglas D. Koch, Department of Ophthalmology, Baylor College of Medicine, 6565 Fannin, NC205, Houston, TX 77030 (e-mail:

Supported, in part, by the AED OCT NIH grant R01 EY018184 and an unrestricted grant from Research to Prevent Blindness, New York, NY. The authors received research support from Ziemer (D.G.K., L.W.). In addition, Dr. Koch has a financial interest with Alcon Laboratories, Abbott Medical Optics, Optimedica, Revision Optics, and Ziemer.

The authors have no funding or conflicts of interest to disclose.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (

Received June 04, 2013

Accepted August 02, 2013

Copyright © 2013 Wolters Kluwer Health, Inc. All rights reserved.