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Raksha Urs, Harriet O Lloyd, Ronald H Silverman; Comparison of Ultrasound and OCT Corneal and Epithelial Thickness Maps . Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1613.
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© ARVO (1962-2015); The Authors (2016-present)
The goal of this study was to compare measurements of corneal and epithelial thickness maps obtained by the RTVue OCT system with those obtained from the Artemis immersion scanning high-frequency ultrasound system and to assess the agreement between the two devices.
Both eyes of 10 normal volunteers were scanned with the Artemis and RTVue. For each corneal thickness map, the minimum corneal thickness (MCT) and mean corneal thickness in 0.5 mm-wide annuli of up to 3 mm radius around the location of MCT were determined. From the epithelial maps, the value of epithelial thickness (ET) at the location of the MCT and mean epithelial thickness in 0.5mm-wide annuli around the location of MCT was determined.
Thickness measurements from Artemis and RTVue thickness maps were 514.3 ± 35.2 µm and 513.6 ± 33.6 µm respectively for MCT and 55.1 ± 2.8 µm and 53.8 ± 3.4 µm for ET. There was high correlation between both the MCT and ETreadings by the two methods (R = 0.99 for MCT and R = 0.78 for ET). Bland-Altman analysis showed that there was no difference between MCT values obtained from the two methods. The mean ET values obtained from Artemis exceeded RTVue values by 1.2 µm. Mean corneal thickness values and epithelial thickness values in each of the 0.5 mm annuli were also highly correlated (R>0.92 for corneal thickness values and R>0.74 for epithelial thickness values). Mean Artemis epithelial thickness values in 0.5 mm annuli rings were slightly higher than RTVue values (1.6 - 2.17 µm). T-testrevealed that the difference in measurements from the two devices were statistically significant. Qualitative inspection of epithelial maps from the two devices revealed similar appearance, but with features appea
Artemis and RTVue corneal and epithelial thickness measurements in the 3 mm radius zone are highly correlated in normal eyes. Artemis epithelial maps were systemically thicker than RTVue epithelial maps. We surmise that this difference could be attributed to signal processing and determination of the back surface of the epithelium.
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