Comparison of Choroidal Vascularity Markers on Optical Coherence Tomography Using Two-Image Binarization Techniques

Abstract

METHODS. Spectral-domain OCT using enhanced-depth imaging was performed in 100 eyes from 52 normal subjects. Choroidal images were binarized to luminal area and stromal area using two different algorithms. Choroidal vascularity marker was defined as the ratio of luminal area to total choroidal area and they were termed ''luminal/choroidal area ratio (L/C ratio)'' and ''choroidal vascularity index (CVI)'' per the algorithm. The agreement between choroidal vascularity markers measured by the two techniques was compared using intraclass correlation coefficient (ICC) and Bland-Altman analysis. RESULTS.The mean values of choroidal vascularity markers were 70.12% (range, 56.76%-78.55%) for CVI and 67.44% (range, 51.09%-81.31%) for L/C ratio. Low level of absolute agreement between the two binarization techniques was reflected by an adjusted ICC of 0.353 using linear mixed model with age, sex, and spherical equivalent as covariates.CONCLUSIONS. There was discrepancy between measurements of choroidal vascularity using two commonly adopted image binarization techniques. It remained unclear what was the true choroidal vascularity and which binarization algorithm was more accurate. Future studies with enhanced image quality and improved image analysis algorithm are required to decipher the ground truth for choroidal vascularity.

New Insights on Choroidal Vascularity: A Comprehensive Topographic Approach

“…31,32 Although CVI values remain precise within studies, accuracy with respect to any specified gold standard such as histology needs to be established. 18,21,33 For instance, Wei et al 34 have compared two commonly used binarization techniques; neither of these was found to be superior, and agreement between them was low. The inherent flaw with these algorithms exists because CVI calculation is based on the simple assumption that dark areas (vascular lumen) and light areas (stroma) are the only two constituents of the choroid.…”

Assessment of choriocapillary blood flow changes in response to half-dose PDT in chronic central serous chorioretinopathy using OCTA

“…Besides, correlation between SFCT and FSV has not been established in this cohort, nor in other reports 31 . It might be related to the relatively small sample size, or that SFCT generally assesses choroidal thickness and both pathologically dilated vessels and increased stromal contribute to the increase of SFCT, future studies could further evaluate the correlation of FSV with other more specific indicators such as choroidal vascularity index (CVI) 3 .…”

“…Choriocapillaris (CC) ischemia processes, along with increased hydrostatic pressure from choroidal pachyvessels, could result in focal or defused RPE barrier breakdown and subsequent SRD [1][2][3] . It has been well documented that PDT, with modified parameters, has a long-term efficacy and safety profile in chronic CSC (CCSC), with less complications and more favorable vision improvement and anatomic resolution of subretinal fluid (SRF) and subfoveal choroidal thickness (SFCT) 1,4 .…”

Assessment of choriocapillary blood flow changes in response to half-dose PDT in chronic central serous chorioretinopathy using OCTA

“…It might be due to the relatively small sample size, or that SFCT generally assesses choroidal thickness and both pathologically dilated vessels and increased stromal contribute to the increase of SFCT. Future studies should further evaluate the correlation of FSV with other more speci c indicators such as choroidal vascularity index (CVI) 3 .…”

“…With advances in fundus imaging technology, the potential mechanism of choroidal hemodynamic changes in central serous chorioretinopathy (CSC) has been gradually understood in studies applying indocyanine green angiography (ICGA) and enhanced depth imaging optical coherence tomography (EDI-OCT) 1 . Choriocapillaris (CC) ischemia processes, along with increased hydrostatic pressure from choroidal pachyvessels, could result in focal or defused retinal pigment epithelium (RPE) barrier breakdown and subsequent serous retinal detachment (SRD) [1][2][3] . It has been well documented that photodynamic therapy (PDT), with modi ed parameters, has a long-term e cacy and safety pro le in chronic CSC (CCSC), with less complications and more favorable vision improvement and anatomic resolution of subretinal uid (SRF) and subfoveal choroidal thickness (SFCT) 1,4 .…”