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. 2016 Jul 25;5(4):7.
doi: 10.1167/tvst.5.4.7. eCollection 2016 Jul.

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

Rupesh Agrawal  1 , Lilian Koh Hui Li  1 , Vikram Nakhate  2 , Neha Khandelwal  1 , Padmamalini Mahendradas  2
Affiliations

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

Rupesh Agrawal et al. Transl Vis Sci Technol. .

Abstract

Purpose: We 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).

Methods: In 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.

Results: There 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.

Conclusions: In 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 relevance: Choroidal 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.

Keywords: Vogt-Koyanagi-Harada disease; choroid; image analysis; optical coherence tomography.

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Figures

Figure 1
Figure 1
Step-by-step illustrations of image binarization using Image J software and the Niblack image binarization technique. Step-by-step illustrations of image segmentation using the Niblack image binarizaton technique. (A) Manual segmentation of the choroid using the polygon tool on Image J. (B) Conversion to 8 bit image for application of auto local threshold. (C) Niblack autolocal threshold used to get clear segmentation of black and white areas on the choroid. (D) Image after the image binarization was done and when image was reconverted back to RGB image. (E) Superimposed image of binarized segment over the original EDI-OCT scan.
Figure 2
Figure 2
Enhanced depth imaging OCT scans of eyes with VKH before (A) and after (B) binarization using the Niblack auto local thresholding technique on Image J software.
Figure 3
Figure 3
Pre- and postbinarized image for one study patient. (A) Visibly thickened choroid on EDI-OCT scan. (B) Segmented image illustrating the choroidal vasculature and stroma at baseline. (C) Illustrates the EDI-OCT scan at 11-month follow-up. (D) Segmented image at follow-up.
Figure 4
Figure 4
Fundus fluorescein angiography (left) and ICGA (right) enface scans in mid phase with image binarization using Niblack auto local threshold technique on Image J software.
Figure 5
Figure 5
Composite box plots. (A) Comparing CT in VKH eyes compared to controls as baseline. (B) Comparing CT in VKH eyes at baseline and at 3–6 months. (C) Comparing CVI in VKH eyes compared to controls as baseline. (D) Comparing CVI in VKH eyes at baseline and at 3–6 months
See this image and copyright information in PMC

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