Comparison of Choroidal Thickness Measurements between Spectral-domain Optical Coherence Tomography and Swept-source Optical Coherence Tomography in Children

PURPOSE: Choroidal thickness is associated with many ocular conditions, interchangeability among different generations of optical coherence tomography is therefore important for both research purpose and clinical application. Hence, we compared choroidal thickness measurements between spectral-domain optical coherence tomography (SD-OCT) and swept-source optical coherence tomography (SS-OCT) in healthy pediatric eyes. METHODS: Children from the population–based Hong Kong Children Eye Study were recruited. Choroidal thickness was measured by both devices. Intra-class correlation coefficient (ICC) was used to compare the measurements. RESULTS: A total of 114 children with mean age of 7.38±0.82 years were included. The central foveal choroidal thickness (CFCT) measured by SD-OCT and SS-OCT was 273.24±54.29μm and 251.84±47.12μm respectively. Inter-device correlation coefficient was 0.840 (95%CI: 0.616-0.918). However, choroidal thickness obtained by SD-OCT was significantly thicker than that measured by SS-OCT with a mean difference of 21.40±33.13μm ( P <0.001). Bland-Altman limit of agreement on the relative difference scale for SD-OCT/SS-OCT was 86.33μm. Validated conversion equation for translating SD-OCT CFCT measurement into SS-OCT was SS-OCT = 35.261 + 0.810 x SD-OCT. CONCLUSIONS: ICC shows an acceptable agreement between SD-OCT and SS-OCT, however, there was a significant inter-device difference of choroidal thickness measurements in normal children eyes. Therefore, the measurements are not interchangeable.