# Segmental choroidal vascularity in Acute Vogt-Koyanagi-Harada disease

## TL;DR

This study examines changes in choroidal structures during and after acute Vogt-Koyanagi-Harada disease using optical coherence tomography.

## Contribution

The study identifies a novel OCT biomarker of resolved VKH disease through the observation of horizontally oval or 'slit-like' choroidal vessels.

## Key findings

- Significant reductions in choroidal thickness and areas were observed after treatment in patients with VKH disease.
- Horizontally oval or 'slit-like' choroidal vessels were found in 91% of eyes after disease resolution.
- Baseline visual acuity and choroidal thickness correlated with post-treatment visual acuity improvement.

## Abstract

To analyse the changes in choroidal structures, both in the inner and outer choroid, including choroidal vascularity index (CVI) and choroidal stromal index (CSI) in patients with Vogt-Koyanagi-Harada (VKH) disease during the acute phase and after disease resolution using optical coherence tomography (OCT).

This was a retrospective, observational study of eyes with acute VKH disease. An automated image binarization protocol was used to analyse the choroid. Choroidal thickness, area, and choroidal vascular and stromal area were calculated using the same protocol. Qualitative changes in the morphology of choroidal vessels were also analysed. Changes in choroidal parameters and correlations before and after treatment were analysed.

We included 55 eyes (29 patients) of acute VKH (9 males and 20 females). Significant reductions were observed in inner, outer, and total choroidal thickness, and in both stromal and vascular areas of the choroid after treatment (p < 0.01). However, no significant changes were noted in CVI or CSI. Additionally, 91% of eyes exhibited a horizontally oval or “slit-like” configuration of choroidal vessels following disease resolution, which was associated with a thinner choroid. On regression analysis, worse visual acuity at baseline and higher inner choroidal thickness were associated with greater improvement in visual acuity, and thinner total choroidal thickness at baseline was associated with thinner choroidal thickness at the final visit.

Choroidal structural parameters in both the inner and outer choroid significantly decrease after VKH disease resolution. However, both CVI and CSI remained unchanged. Also, horizontally oval or “slit-like” choroidal vessels may be a novel OCT biomarker of resolved VKH disease.

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