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T. Miyake, H. Mori, Y. Watanabe, Y. Yasuno, H. Goto; Measurement of Radius of Corneal Curvature Using Three Dimensional Anterior Segment Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1869.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the radius of corneal curvature measured by three dimensional corneal and anterior segment optical coherence tomography (3-D CAS-OCT) to that measured by conventional autokeratometer.
Seventy two eyes of 36 patients with regular astigmatism were prospectively examined. The mean age of the subjects was 29.5±8.2 (mean±SD) years old. 3-D CAS-OCT prototype based on swept-source OCT with a probe wavelength of 1,300nm was built by Computational Optics Group in the University of Tsukuba and TOMEY Corporation (Aichi, Japan). The transversal measurement range was 16 mm×16 mm, and a raster-scanning protocol with 256A-lines×256B-mode images was used. The scanning rate was 20,000 A lines/s, and the acquisition time was 3.3sec for a volume. Radius of corneal curvature was calculated within the central 6.0mm corneal diameters based on circular approximation. Radius of corneal curvature measured by 3-D CAS-OCT was compared with that measured by autokeratometer RC-5000 (TOMEY Corporation) in the greatest and least meridians based on the coefficient of concordance and Bland-Altman analysis.
Radiuses of corneal curvature measured by 3-D CAS-OCT in the greatest and the least meridians were 7.99±0.23mm and 7.83 ±0.42mm. Radiuses of corneal curvature measured by autokeratometer were 7.97±0.19mm and 7.79 ±0.18mm, respectively. Coefficient of concordance in the greatest and least meridian were 0.64(precision:0.65, accuracy:0.98) and 0.55(precision:0.54, accuracy:0.84). Bland-Altman analysis showed that radius of corneal curvature in the greatest and the least meridians measured by 3-D CAS-OCT were higher by 0.3 (limits of agreement -4.7 to 4.2) and 0.5 (limits of agreement -10.5 to 9.5).
3-D CAS-OCT provided very similar values of the radius of corneal curvature to that provided by autokeratometry, although the radius measured by 3-D CAS-OCT was slightly higher than that of autokeratometry.
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