Effects of age and binarising area on choroidal vascularity index in healthy eyes: an optical coherence tomography study.

Abstract

To investigate the changes in the choroidal vascularity index (CVI) with age and to compare the effect of the binarised area on CVI in healthy eyes using spectral-domain optical coherence tomography (SD-OCT). Two hundred and twenty-four eyes of 224 healthy subjects were included in this prospective cross-sectional study.The eyes were divided into different age groups to analyse the possible age-related choroidal structural changes. Subfoveal choroidal thickness (SFCT), CVI, total choroidal area (TCA), stromal area (SA), luminal area (LA), and CVI within the central 1500µm of the macula were analysed using enhanced depth imaging SD-OCT. The CVI was defined as the proportion of the LA to the TCA, and its values for the two binarised areas were compared (CVItotal vs. CVI1500). The mean age was 34.77 ± 20.97 (range: 5-70) years. The mean CVItotal was statistically lower (66.71 ± 2.58%) than the mean CVI1500 (67.54 ± 3.13%, p = 0.008) among all the healthy participants. TCA, LA, CVItotal, and CVI1500 were statistically higher in the ≤ 18-year-old group compared to the > 18-year-old group (p < 0.05), but SA was not significantly different between the groups (p = 0.327). Similarly, TCA, LA, CVItotal, and CVI1500 between the five studied age groups were statistically different (p < 0.001), showing larger figures in the 0-10-year-old group. However, this was not true for the stromal region (p = 0.139). CVItotal exhibited a very strong positive correlation with CVI1500. No significant gender-related difference was observed in CVI. Decreased LA, TCA, and CVI were observed in healthy eyes with increasing age. CVI1500 was higher than CVItotal in a single B scan OCT. This result may provide valuable information about the choroid under different conditions, such as its physiological changes and disease pathophysiology.