Comparison of choroidal thickness using swept-source and spectral-domain optical coherence tomography in normal Indian eyes

BACKGROUND/AIMS Choroidal thickness measurements are reported to differ between spectral-domain optical coherence tomography (SD-OCT) and swept-source OCT (SS-OCT). The aim of this study was to assess the comparability of choroidal thickness measurements using SS-OCT and SD-OCT devices among normal participants. MATERIALS AND METHODS This was a prospective study of 31 (62 eyes) normal participants. Choroidal imaging was performed sequentially with the Spectralis OCT (SD-OCT) and the deep range imaging OCT (DRI OCT-1) (SS-OCT) using standardized imaging protocols. The subfoveal choroidal thickness (SFChT) was measured manually by two masked retinal specialists. Paired t-tests and intraclass correlation coefficients (ICCs) were used to compare the measurements. RESULTS The mean SFChT was 319.5 μm and 325.3 μm for DRI OCT-1 and Spectralis OCT, respectively (P = 0.001), with a mean difference of 5.9 with ICC of 0.97. The mean difference in choroidal thickness between the OCT devices was larger among eyes with choroidal thickness > 350 μm compared with eyes with thinner choroids (8.0 μm vs. 4.7 μm). CONCLUSIONS SFChT measurements are comparable between DRI OCT-1 and Spectralis OCT. The variability between the devices increases in thicker choroids.