Objective To investigate the repeatability and reproducibility of mapping the entire corneal thickness of keratoconic patients using long scan depth spectral domain OCT （UL-OCT）. Methods Ten patients （10 eyes） with keratoconus were recruited for this prospective study. A custom-built UL-OCT system was used to obtain radial frames of corneal images. The 3D scan pattern consisted of equally located B-scans centered on the corneal vertex reflection. Corneal thickness maps were generated by a fully automated segmentation algorithm over a 10 mm diameter of the corneal region. Corneal thicknesses were measured in the central zone （0-2 mm）， pericentral zone （>2-5 mm）， transitional zone （>5-7 mm） and peripheral zone （>7-10 mm）. The results were compared with those obtained with a Pentacam. The intraobserver repeatability and interobsever reproducibility of the two systems were analyzed by a coefficient of repeatability （CoR）， coefficient of reproducibility （CoR）， intraclass correlation coefficient （ICC） and coefficient of variation （CV）. The differences between the two systems were analyzed by a paired t test and Bland-Altman method. Results For keratoconus UL-OCT measurements， the coefficients of repeatability were less than 4.31 μm and the coefficients of reproducibility were less than 8.10 μm. The intraclass correlation coefficients of repeatability and reproducibility were more than 0.998 and 0.995. For the Pentacam topography of keratoconic patients， the coefficients of repeatability were less than 14.30 μm and coefficients of reproducibility was less than 19.17 μm. ICCs of repeatability and reproducibility were more than 0.997 and 0.994. The UL-OCT system measurements of corneal thickness in the central zone， pericentral zone， transitional zone and peripheral zone were 468.9±38.6 μm， 482.5±48.6 μm， 515.5±57.0 μm， and 588.0±52.5 μm， respectively. Pentacam system measurements of corneal thickness in the same zones were 500.9±50.0 μm， 533.9±49.7 μm， 587.9±60.6 μm， and 635.3±62.0 μm， respectively. The Bland-Altman analysis showed that the 95% limits of agreement between the two instruments in the central zone， pericentral zone， transitional zone were -44.49 to 108.59 μm， -7.47 to 110.23 μm， and 13.21 to 131.68 μm， respectively. Conclusion There were significant differences in thickness measurements between UL-OCT and Pentacam topography， which makes these two devices non-interchangeable in the clinic.
沈梅晓,彭梅,姬戎媛,许哲,荆树栋,马庆凯,吕帆,姜珺. 长扫描深度谱域OCT测量圆锥角膜患者全角膜厚度的重复性和再现性[J]. 中华眼视光学与视觉科学杂志, 2014, 16(6): 354-358.
Shen Meixiao,Peng Mei,Ji Rongyuan,Xu Zhe,Jing Shudong,Ma Qingkai,Lyu Fan,Jiang Jun. Repeatability and reproducibility of mapping the entire corneal thickness of keratoconic patients using long scan depth spectral domain OCT . Chinese Journal of Optometry Ophthalmology and Visual Science, 2014, 16(6): 354-358. DOI: 10.3760/cma.j.issn.1674-845X.2014.06.008
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