Choroidal Vascularity Index in Vogt-Koyanagi-Harada Disease: An EDI-OCT Derived Tool for Monitoring Disease Progression

Abstract

PurposeWe assessed the application of the choroidal vascularity index (CVI) in the follow-up of Vogt-Koyanagi-Harada disease (VKH) patients derived from image binarization of enhanced depth imaging optical coherence tomography (EDI-OCT) images with Fiji software. Our secondary objective was to derive the retinochoroidal vascularity index based on en face fundus fluorescein and indocyanine green angiography (FFA and ICGA).MethodsIn this retrospective cohort study, EDI-OCT scans of 18 eyes of 9 patients with VKH were obtained at baseline within 2 weeks of acute presentation, and again at 6 to 12 months. Images with poor quality were excluded. Choroidal thickness (CT) and CVI were analyzed and compared to 13 eyes of 13 healthy controls. En face FFA and ICGA obtained from 12 eyes of 7 patients were segmented to derive retinochoroidal vascularity index.ResultsThere was no statistical difference in age or sex between the study group and controls. Choroidal thickness of patients with VKH was 359.23 ± 57.63 μm at baseline, compared to 274.09 ± 56.98 μm in controls (P = 0.003). Follow-up CT in VKH patients was 282.62 ± 42.51 μm, which was significantly decreased from baseline (P = 0.0001). Choroidal vascularity index in VKH patients was 70.03 ± 1.93% at baseline, compared to 64.63 ± 1.92% in controls (P < 0.001). Choroidal vascularity index was 66.94 ± 1.82% at follow-up, significantly reduced from baseline (P < 0.0001). Fundus fluorescein angiography and ICGA retinochoroidal vascularity indices at baseline were 70.67 ± 2.65% and 66.42 ± 2.16%, respectively.ConclusionsIn this small series of VKH patients, EDI-OCT–derived CVI had a statistically significant reduction over time, similar to CT. We propose that OCT, FFA, and ICGA-derived vascularity indices may be potential novel supportive tools in monitoring disease progression in VKH.Translational RelevanceChoroidal vascularity index can be used potentially to study and analyze the structural changes in choroid. It can be a useful tool to explain the changes in the CT in different retinochoroidal disorders. Choroidal vascularity index also can be used for longitudinal follow-up in patients with VKH disease and other inflammatory disease involving the choroid.

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

“…CVI but not CT, was shown to be independent from systemic and ocular factors such as age, axial length, intraocular pressure, or systolic blood pressure in a large study involving 345 normal subjects. 20 In eyes from diabetic patients and eyes with exudative AMD, there were decreased CVI with no significant change in CT. 26,28,29 CVI was also shown to provide additional information to CT in terms of longitudinal choroidal structural changes in diseases such as panuveitis 20 ; Vogt-Koyanagi-Harada (VKH) disease 25 ; central serous chorioretinopathy (CSCR) 24 ; and myopic choroidal neovascularization. 27 Changes in L/C ratio or a similar index called L/S ratio (ratio of choroidal luminal area to stromal area) were investigated and found to yield valuable information in normal physiologic conditions including diurnal variation 22 and dynamic exercise 23 as well as in a number of ocular diseases including exudative AMD 21 ; polypoidal choroidal vasculopathy (PCV) 34 ; CSCR 32,33 ; VKH disease 30,31 ; and retinitis pigmentosa.…”

“…It was termed ''choroidal vascularity index (CVI)'' by Agrawal et al 19 or ''luminal/choroidal area ratio (L/C ratio)'' by Sonoda et al 18 This new marker of choroidal vascularity has been investigated in normal physiologic conditions 18,[20][21][22][23] and also validated as a useful tool in various ocular diseases. 19,[24][25][26][27][28][29][30][31][32][33][34][35][36] Differences exist in the image binarization algorithms for the calculation of CVI and L/C ratio. 20 Although they are measuring the same entity, there is no direct head-to-head comparison between the two.…”

Peripapillary Choroidal Vascularity Index in Glaucoma—A Comparison Between Spectral-Domain OCT and OCT Angiography

“…Niblack's 23 autolocal threshold techniques were used for image binarization. 9,[11][12][13][14] The choroidal area was defined as the area between the upper border marked at the RPE and the lower border of light pixels at the choroid scleral junction (Figs. 1A4, 1A5, 1B4, 1B5).…”

“…Recently, in vivo quantification of the choroidal vasculature outside the bPPA based on the reflectivity of the choroidal structure as imaged by spectral-domain OCT (SD-OCT) was newly introduced. [9][10][11][12][13][14][15][16][17] Specifically, there are a number of reports regarding the clinical relevance of the choroidal vascularity index (CVI) for various retinal diseases. 9,[11][12][13][14][15][16] The purpose of the present study was to determine the total choroidal area (TCA) and CVI by means of image binarization of SD-OCT images and to compare them between glaucomatous eyes with and without OCT-A-determined MvD_P.…”

Choroidal structural analysis and vascularity index in retinal dystrophies

“…), Vogt‐Koyanagi‐Harada disease (Agrawal et al. ), central serous chorioretinopathy (Agrawal et al. ) and myopic choroidal neovascularization (Ng et al.…”