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A. Anraku, J. Mok, Y. Buys, G. Trope, J. Flanagan; Comparison of Retinal Nerve Fiber Layer Thickness as Mesured by Two Spectral Domein Optical Coherence Tomographers. Invest. Ophthalmol. Vis. Sci. 2010;51(13):252. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the relationships between retinal nerve fiber layer (RNFL) thickness measured by the Cirrus HD optical coherence tomography (COCT; Carl Zeiss Meditec) and the Spectralis HRA+OCT (SOCT; Heidelberg Engineering).
The RNFL thickness was measured by the COCT and SOCT in 32 patients with early or moderate glaucoma. Measurements were performed by one operator and repeated within 3 months. At the second visit, images were acquired using both the follow-up mode and the regular single image mode of the SOCT. The RNFL thickness was compared using repeated measures ANOVA and the between test agreement and within instrument repeatability were evaluated using the methods of Bland-Altman.
The average global RNFL thickness was 74.94µm for the COCT and was significantly thicker at 77.99µm for the SOCT (p=0.007). The mean of differences (MoD) was -3.05 ± 5.91µm and the limit of agreement (LoA) was -14.64 to 8.54 um. The inferior quadrant gave the thickest RNFL, followed by the superior, nasal and temporal quadrants. The temporal quadrant showed the smallest LoA (-18.33 to 2.71 um) and nasal quadrant showed the largest LoA (-20.18 to 31.24 um). Both OCTs gave good repeatability, the within instrument MoD for average RNFL for the COCT was 0.09µm (coefficient of repeatability; CoR=5.02) and for SOCT -0.1µm (CoR=7.85). In follow-up mode the SOCT showed significantly improved repeatability (MoD= -0.25µm and CoR=4.54).
The SOCT demonstrated significantly thicker RNFL measurements than COCT. Both OCTs gave good repeatability and the SOCT showed the best repeatability when using the follow-up mode.
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