Reproducibility of choroidal thickness measurements in subjects on 3 spectral domain optical coherence tomography machines

The purpose of this study was to investigate the reproducibility of choroidal thickness measurements in normal subjects on 3 spectral domain optical coherence tomography instruments, namely: Zeiss Cirrus HD-OCT (Carl Zeiss Meditec Inc., Dublin, CA), Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany), and Optovue RTVue (Optovue Inc., Fremont, CA). This cross-sectional non-interventional study was performed in a single institution. Images were obtained in 47 eyes of 47 healthy volunteers which age ranged between 23 and 72 without ocular pathology. All subjects were imaged on the fovea using Cirrus HD 1-line raster, Spectralis enhanced depth imaging, and RTVue retina-cross. The choroid was measured subfoveally and at intervals of 500 µm from the fovea nasally and temporally up to 2500 µm. Paired t test, modified Bland-Altman plot, and Pearson's correlation were used to compare the results. There is no significant difference between the systems for any measurement within 2500 µm either side of the fovea for most points. Inter-observer correlation was strong for RTVue, and moderate in both Cirrus and Spectralis.