Reproducibility of Choroidal Thickness Measurements Across Three Spectral Domain Optical Coherence Tomography Systems

Abstract

Purpose To investigate the reproducibility of choroidal thickness measurements in normal subjects on three Spectral Domain Optical Coherence Tomography (SDOCT) instruments, Zeiss Cirrus HD-OCT (Carl Zeiss Meditec Inc, Dublin, California, USA), Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany) and Optovue RTVue (Optovue Inc., Fremont, CA). Design Cross-sectional non-interventional study Participants Images were obtained in 28 eyes of 28 healthy undilated volunteers without ocular pathology in a clinical setting. Methods All subjects were imaged on the fovea using Cirrus HD 1-line raster, Spectralis enhanced depth imaging and RTVue retina-cross. Main Outcome Measures The choroid was measured subfoveally, 750 μm temporal and 750 μm nasal to the fovea. All measurements were performed by 2 independent observers. Two way analysis of variance (ANOVA) with Bonferroni's post-test, Pearson correlation and the Bland-Altman analysis were used to compare measurements. Results The group of 28 subjects consisted of 7 men and 21 women, with an average age of 35.2 years (range, 23 to 64 years). A two way ANOVA with Bonferroni's post-test revealed no significant difference in the average subfoveal choroidal thickness (P >0.05) between systems for any location: subfoveally, 750μm temporal and 750 μm nasal to the fovea. The measurements of choroidal thickness from any pair of three instruments (Cirrus vs. Spectralis, Cirrus vs. RTVue, Spectralis vs. RTVue) were also strongly correlated. The Pearson correlation between all two system pairs of the three systems was greater than 0.9 p <0.0001. The 95% limits of agreement between four choroidal thickness measurements between Cirrus and RTVue were +11.21% to -13.57% (Bias -1.17), between Spectralis and RTVue +10.85% to -12.45% (Bias -0.80) and between Cirrus and Spectralis +12.81% to -13.33% (Bias -0.25). Conclusions In our population of young healthy adults with normal vision, there was good reproducibility between choroidal thickness measurements of images acquired with Cirrus, Spectralis and RTVue.