To propose the use of choroidal vascularity index (CVI) as a novel tool to assess vascular status of the choroid using image binarization of enhanced depth imaging (EDI) optical coherence tomography (OCT) scans in diabetes mellitus (DM).Methods:
A prospective cross-sectional study was performed at a tertiary referral eye care centre in Singapore. Age and gender matched EDI-OCT scans of 38 eyes of 19 patients with DM were compared with eyes of healthy controls (n= 19). The choroidal images were binarized into luminal areas (LA) and stromal areas (SA). Choroidal vascularity index (CVI) was defined as the proportion of LA to total circumscribed subfoveal choroid area (TCA). Mean choroidal thickness, mean retinal thickness and mean CVI between patients and controls were compared using student's t-test.Results:
There were no significant differences in TCA (p = 0.78), LA (p = 0.90), SA (p = 0.33), average choroidal (p = 0.40) or retinal thickness (p = 0.70) between patients with DM and controls. However, there was a significantly lower CVI in patients with DM as compared to controls (65.10 ± 0.20 versus 67.20 ± 0.16, p < 0.0001).Conclusion:
Eyes of patients with DM showed decreased CVI with no corresponding change in choroidal thickness. Image binarization may be potentially useful as a tool to assess choroidal structures and vasculature.