Retinal Pigment Epithelial Characteristics in Acute and Resolved Vogt-Koyanagi-Harada Disease

Vogt-Koyanagi-Harada (VKH) disease is an auto-immune inflammatory disease of choroidal origin. During the acute stage, optical coherence tomography (OCT), however, may not be able to assess the entire choroid. The aims of the paper were to evaluate the role of retinal pigment epithelium (RPE) as a biomarker of inflammation in acute VKH. This was a retrospective observational study done in 55 eyes of 29 patients with acute VKH. RPE thickness, total choroidal thickness, and RPE reflectivity before and after resolution were analyzed using image J software. Correlations between several baseline and post-resolution parameters were performed, and factors affecting change in visual acuity were analyzed. A significant decrease in RPE thickness and a significant increase in RPE reflectivity were seen following resolution of the disease. Furthermore, there was a significant correlation between RPE and choroidal thickness during the acute stage of the disease. Baseline visual acuity and the presence of bacillary detachment at baseline were the only factors responsible for changes in visual acuity. We propose the utility of RPE layer as a surrogate biomarker of choroidal activity and inflammation in terms of RPE reflectivity and RPE thickness during the acute stage of VKH, especially when there is poor imaging of the choroid.