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L. M. Zangwill, G. Vizzeri, C. Bowd, A. O. Gonzalez-Garcia, F. A. Medeiros, R. N. Weinreb; RNFL Thickness Measurements With Cirrus HD-OCT and Stratus OCT. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4629.
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© ARVO (1962-2015); The Authors (2016-present)
To assess the agreement between RNFL thickness measurements from Cirrus (high definition spectral domain) and Stratus (time domain) optical coherence tomography (OCT) instruments.
38 eyes (22 OD, 16 OS) of 26 healthy subjects (mean age 61.37, S.D.= 9.07 years, 15 females) from the Diagnostic Innovations in Glaucoma Study (DIGS) were imaged, according to instrument manufacturer protocol, using the Cirrus HD-OCT (Carl Zeiss Meditec, pre-release analysis software) and the older generation Stratus OCT (Carl Zeiss Meditec, software version 4.0.7) within a single session. Global and sectoral (i.e., clock-hour) RNFL thicknesses were compared between instruments, correlation coefficients were calculated and Bland-Altman plots with 95% limits of agreement were constructed to estimate the agreement between measurements. In addition, repeatability of measurements obtained using Cirrus was determined for a subset of 30 eyes (15 OD, 15 OS), imaged 3 times each. Coefficients of variation (CV) and intra-class correlation coefficients (ICC) were calculated to assess repeatability of all investigated measurements.
In general, RNFL thickness measurements were greater for the Stratus OCT, with differences between instruments ranging from 7.6 microns for 12 Clock Hour Thickness to 19.4 microns for 3 Clock Hour Thickness. Correlations between measurements were moderate (r = 0.46 for 3 Clock Hour Thickness) to strong (r = 0.95 for Average RNFL Thickness) and 95% limits of agreement ranged from -31 to 36.7 mcirons for 6 Clock Hour Thickness to -0.1 to 16.3 microns for Average RNFL thickness. For Cirrus, repeatability of Average RNFL Thickness was better than repeatability of sectoral thicknesses. CVs ranged from 1.4% for Average RNFL Thickness to 6.4% for 2 Clock Hour Thickness and ICCs were 0.98 and 0.83, respectively.
In general in these healthy eyes, global RNFL thickness measured with the Cirrus and Stratus OCT were more similar than sectoralmeasurements. Moreover, the superior and inferior sector Stratus and Cirrus OCT RNFL thickness measurements were more similar than the nasal and temporal ones.
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