Purpose:
To determine if sub-perifoveal choroidal thickness was similar in different image capture techniques across 3 SD-OCT systems and to compare the continuity of the choroidal-scleral junction (CSJ). This is the first comparison of these parameters across systems.
Methods:
In a prospective comparative case series, 22 eyes from 12 normal subjects had 9 mm fovea-centered horizontal line scans containing 1536 A-scans/B-scan (1024 Cirrus) and 40 averaged B-scans per image (20 Cirrus) using 7 SD-OCT image capture techniques: Bioptigen, Cirrus, Spectralis (upright/inverted), and Spectralis EDI mode. The inner and outer choroid borders were manually segmented by 2 masked observers. Average choroidal thickness across a fovea-centered 4 mm segment was determined with MATLAB. Image quality was defined by the percentage of images with >90% continuity of the CSJ. Statistical analyses: student’s paired t-test and Pearson correlation for inter-observer correlation (IOC) (p< 0.05 was statistically significant).
Results:
Mean choroidal thickness was higher in inverted verses upright modes, except in Cirrus (Table 1). Spectralis EDI also had significantly thicker choroid than Spectralis upright. IOC was highest in inverted Bioptigen and Spectralis, Spectralis EDI, and upright Cirrus. CSJ scores were higher for inverted (and EDI) verses upright, except in Cirrus: Bioptigen (67%, 29%, p=0.02), Spectralis (72%, 28%, p=0.004), Spectralis EDI (61%, p=0.04), Cirrus (0%, 58%, p<0.001). Cirrus upright CSJ continuity did not differ from Bioptigen and Spectralis inverted (p >0.4).
Conclusions:
For these imaging parameters, inverted imaging in Bioptigen and Spectralis resulted in higher choroidal thickness measurements because of improved visualization of the CSJ/outer choroid. Upright Cirrus compares favorably with inverted Bioptigen and Spectralis in terms of choroid thickness and CSJ. IOC was higher in modes with better CSJ quality.
Keywords: choroid • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)