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Repeatability of corneal epithelial thickness measurements using Fourier-domain optical coherence tomography in normal and post-LASIK eyes.

ABSTRACT: 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).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.At the central and paracentral zones, respectively, the SD values were 0.7 ?m and 0.6 to 0.9 ?m in normal eyes and 0.7 ?m and 0.8 to 1.7 ?m in LASIK-treated eyes for ET, and 1.0 ?m and 2.8 to 4.6 ?m in normal eyes and 1.3 ?m and 4.0 to 4.8 ?m 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 ?m and 1.4 to 2.2 ?m for ET, and 4.1 to 6.4 ?m and 6.0 to 9.1 ?m 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.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.

SUBMITTER: Ma XJ

PROVIDER: S-EPMC4038409 | biostudies-literature | 2013 Dec

REPOSITORIES: biostudies-literature

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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 XJ Wang Li L Koch Douglas D DD

Cornea 20131201 12

<h4>Purpose</h4>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).<h4>Methods</h4>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- ...[more]

PMID: 24145634

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Project description:ObjectiveTo map the corneal epithelial thickness with Fourier-domain optical coherence tomography (OCT) and to develop epithelial thickness-based variables for keratoconus detection.DesignCross-sectional observational study.ParticipantsOne hundred forty-five eyes from 76 normal subjects and 35 keratoconic eyes from 22 patients.MethodsA 26,000-Hz Fourier-domain OCT system with 5-μm axial resolution was used. The cornea was imaged with a Pachymetry + Cpwr scan pattern (6-mm scan diameter, 8 radials, 1024 axial-scans each, repeated 5 times) centered on the pupil. Three scans were obtained at a single visit in a prospective study. A computer algorithm was developed to map the corneal epithelial thickness automatically. Zonal epithelial thicknesses and 5 diagnostic variables, including minimum, superior-inferior (S-I), minimum-maximum (MIN-MAX), map standard deviation (MSD), and pattern standard deviation (PSD), were calculated. Repeatability of the measurements was assessed by the pooled standard deviation. The area under the receiver operating characteristic curve (AUC) was used to evaluate diagnostic accuracy.Main outcome measuresDescriptive statistics, repeatability, and AUC of the zonal epithelial thickness and diagnostic variables.ResultsThe central, superior, and inferior epithelial thickness averages were 52.3 ± 3.6 μm, 49.6 ± 3.5 μm, and 51.2 ± 3.4 μm in normal eyes and 51.9 ± 5.3 μm, 51.2 ± 4.2 μm, and 49.1 ± 4.3 μm in keratoconic eyes. Compared with normal eyes, keratoconic eyes had significantly lower inferior (P = 0.03) and minimum (P<0.0001) corneal epithelial thickness, greater S-I (P = 0.013), more negative MIN-MAX (P<0.0001), greater MSD (P<0.0001), and larger PSD (P<0.0001). The repeatability of the zonal average, minimum, S-I, and MIN-MAX epithelial thickness variables were between 0.7 and 1.9 μm. The repeatability of MSD was better than 0.4 μm. The repeatability of PSD was 0.02 or better. Among all epithelial thickness-based variables investigated, PSD provided the best diagnostic power (AUC = 1.00). Using an PSD cutoff value of 0.057 alone gave 100% specificity and 100% sensitivity.ConclusionsHigh-resolution Fourier-domain OCT mapped corneal epithelial thickness with good repeatability in both normal and keratoconic eyes. Keratoconus was characterized by apical epithelial thinning. The resulting deviation from the normal epithelial pattern could be detected with very high accuracy using the PSD variable.Financial disclosure(s)Proprietary or commercial disclosure may be found after the references.

Dataset Information

Repeatability of corneal epithelial thickness measurements using Fourier-domain optical coherence tomography in normal and post-LASIK eyes.

Publications

Repeatability of corneal epithelial thickness measurements using Fourier-domain optical coherence tomography in normal and post-LASIK eyes.

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