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J. M. Fullerton, J. E. Kim, Q. Xiang, A. Szabo; Comparison of Spectral Domain OCT and Time Domain OCT for Measurements of Retinal Thickness. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1073.
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© ARVO (1962-2015); The Authors (2016-present)
To compare retinal macular thickness measurements acquired by Spectral Domain (SD) and Time Domain (TD) Optical Coherence Tomography (OCT) in normal and diseased human retina.
Charts and OCT studies of patients who underwent both SD OCT (Spectralis, Heidelberg Engineering, Heidelberg, Germany) and TD OCT (Stratus, Carl-Zeiss Meditec, Dublin, CA) of the same eye on the same date were retrospectively reviewed. Macular thickness of the central (1mm), inner (3mm), and outer (6mm) nasal, inferior, temporal, and superior subfields were compared in individuals with normal and diseased retina. The agreement between TD and SD OCT was evaluated via a paired t-test to assess bias, and Pearson correlation to assess the strength of the relationship. Thickness as well as each of the 9 subfields were evaluated separately. Bias estimates and Fisher’s z-transformed correlations at different distances were compared using a linear model inversely weighted by the variance of the estimates.
100 eyes of 68 patients were studied. TD OCT reported a consistently lower thickness than SD OCT (all p<0.0001) with a mean bias of 62um (95% CI: 54-70um) in the center 1mm region, similar values of bias in the four regions within the 3mm circle (55, 58, 66, 62um, in the nasal, inferior, temporal, and superior regions, respectively, p=0.63 vs. the 1mm region) and significantly lower bias in the four regions between the 3 and 6mm circles (47, 50, 52, 54um, p=0.038 vs. the 1mm circle). The correlation between TD and SD OCT thickness measurements was high in all regions (all p<0.0001). The highest correlation was observed in the center 1mm region (r=0.93, 95% CI: 0.90-0.95), with non-significantly lower values in the four regions within the 3mm circle (r=0.89, 0.89, 0.83, 0.88 in the nasal, inferior, temporal, and superior regions, respectively, p=0.23 vs. the 1mm region), and significantly lower values in the four regions between the 3 and 6mm circles (r=0.88, 0.77, 0.63, 0.79, with p=0.037 vs. the 1mm circle).
TD OCT gives thickness measurements that are consistently lower but highly correlated with SD OCT results. Both the bias and the strength of correlation are lower in the regions furthest from the center.
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