Using a custom-developed segmentation algorithm, agreement of corneal epithelial thickness
profile measurements between two spectral domain optical coherence tomography (SD-OCT
) systems was assessed.
Eighteen left eyes (18 subjects; mean±standard deviation; age, 23.2±0.9 years) were imaged twice on nonconsecutive days by a custom-built ultra-high resolution OCT (UHR-OCT) system and a commercial RTVue OCT system. A segmentation algorithm based on axial gradient information and a shortest path search was developed to measure corneal epithelial thickness
profiles from the SD-OCT
There was good correlation between the automated and manual segmentation positions of the epithelium. The epithelial thickness
differences between automated and manual segmentations by the UHR-OCT and RTVue OCT systems were 0.4±0.3 μm and 1.1±0.5 μm, respectively. The intraclass correlation coefficients (ICCs) and coefficients of repeatability for repeated UHR-OCT measurements of epithelial thickness
were 0.90±0.05 μm and 1.44±0.01 μm, respectively. For RTVue OCT, the ICCs and coefficients of repeatability were 0.88±0.04 μm and 2.16±0.01 μm, respectively. The epithelial thickness
measured by RTVue OCT was 1.1±0.2 μm greater than that by UHR-OCT (P
<0.05, paired t
test), and ICC for the agreement between the 2 systems was 0.85±0.06. The average 95% limit of agreement was −1.67 to 3.79 μm.
For images of different qualities from both SD-OCT
systems, the custom-developed automated segmentation
of the corneal epithelium had good repeatability for thickness profile measurements. The accurate and precise algorithm also demonstrated good agreement of epithelial thickness
profile measurements between the two SD-OCT