Choroidal thickness maps from spectral domain and swept source optical coherence tomography: algorithmic versus ground truth annotation

Abstract

Background/aims The purpose of the study was to create a standardised protocol for choroidal thickness measurements and to determine whether choroidal thickness measurements made on images obtained by spectral domain optical coherence tomography (SD-OCT) and swept source (SS-) OCT from patients with healthy retina are interchangeable when performed manually or with an automatic algorithm. Methods 36 grid cell measurements for choroidal thickness for each volumetric scan were obtained, which were measured for SD-OCT and SS-OCT with two methods on 18 eyes of healthy volunteers. Manual segmentation by experienced retinal graders from the Vienna Reading Center and automated segmentation on >6300 images of the choroid from both devices were statistically compared. Results Model-based comparison between SD-OCT/SS-OCT showed a systematic difference in choroidal thickness of 16.26±0.725 μm (p<0.001) for manual segmentation and 21.55±0.725 μm (p<0.001) for automated segmentation. Comparison of automated with manual segmentations revealed small differences in thickness of −0.68±0.513 μm (p=0.1833). The correlation coefficients for SD-OCT and SS-OCT measures within eyes were 0.975 for manual segmentation and 0.955 for automatic segmentation. Conclusion Choroidal thickness measurements of SD-OCT and SS-OCT indicate that these two devices are interchangeable with a trend of choroidal thickness measurements being slightly thicker on SD-OCT with limited clinical relevance. Use of an automated algorithm to segment choroidal thickness was validated in healthy volunteers.

Choroidal Thickness and Choroidal Vessel Density in Nonexudative Age-Related Macular Degeneration Using Swept-Source Optical Coherence Tomography Imaging

“…In the last few years, several groups have generated choroidal thickness maps of various sizes either manually 6,29 or using automated algorithms. 23,32–37 Swept-source OCT imaging at longer wavelengths has several clear advantages over SD-OCT imaging, such as increased penetration through the RPE, decreased sensitivity roll-off, and higher scanning speeds, which enable larger areas to be scanned and/or higher A-scan density. 38 Therefore, SS-OCT provides the opportunity to generate wide-field choroidal thickness maps and enables the study of large-scale structures, such as the distribution of the large choroidal vessels and their association with the pattern of choroidal thickness measurements.…”

Impact of image averaging on wide‐field choroidal thickness measurements using enhanced‐depth imaging optical coherence tomography

“…Estimates of choroidal thickness may be affected by the number of frames used for B‐scan averaging due to the smoothing effect and improved visibility of the posterior border of the choroid associated with image averaging . However, in the healthy young adults participating in this study, no evidence of significant change in regional estimates of wide‐field choroidal thickness was found across a 60° area associated with the number of frames used for B‐scan averaging, suggesting that using a different number of frames for B‐scan averaging during EDI‐OCT imaging does not introduce a significant bias in measurements of choroidal thickness.…”

Subfoveal choroidal thickness at age 9 years in relation to clinical and perinatal characteristics in the population‐based Generation R Study

“…It should be noted that there may be a systematic offset between the present study's use of cycloplegia and swept-source optical coherence tomography (SS-OCT) instead of the CCC2000's use of spectral-domain optical coherence tomography (SD-OCT) without cycloplegia. The SS-OCT instrument been reported to find an approximately 20-lm-thinner choroid than the SD-OCT instrument (Philip et al 2016). Cycloplegia has been reported to increase choroidal thickness ( € Oner et al).…”

“…The SS‐OCT instrument been reported to find an approximately 20‐ μ m‐thinner choroid than the SD‐OCT instrument (Philip et al. ). Cycloplegia has been reported to increase choroidal thickness (Öner et al.…”