Choroidal Vasculature from Ultra-Widefield Images without Contrast Dye and Its Application to Vogt-Koyanagi-Harada Disease

Abstract

To develop a method to obtain ultra-widefield choroidal vessel images with a fundus camera without using dye, and its application in Vogt-Koyanagi-Harada (VKH) disease. Experimental study and case series. Patients with unilateral retinal disorders and those with VKH disease who had undergone ultra-widefield imaging were studied. Indocyanine green angiography (ICGA) and the 635-nm wavelength Optos ultra-widefield fundus photography (Optos, United Kingdom) images (Optos635-nm) were processed by KagoEye 3 software. The 2 types of images were overlapped. The degree of overlapped blood vessel areas of the ICGA image was taken as the matching ratio. The matching ratio was obtained for the peripheral, posterior pole, and overall areas. In addition, changes in the fundus findings were followed up with Optos635-nm image analysis in patients with VKH disease. The degree of visibility of the choroidal vessels was evaluated for 5 stages. The clarity scores and the longitudinal findings were compared. The matching ratios between the ICGA images and the Optos635-nm images processed by KagoEye3 software were determined. Initially, 10 healthy eyes were studied. The matching ratios for the overall area, the peripheral area, and the posterior pole area of the ICGA image and the Optos635-nm image were 64.09%, 74%, and 63.10%, respectively. The correlations between the choroidal blood vessel matching ratio and the ocular axial length and refractive error were not significant, but the matching ratio was correlated significantly with the age. The average clarity score in 12 VKH disease patients was 1.6 ± 0.85 before treatment, which was significantly improved to 4.2± 0.75 after 1 month (P < 0.05). Many hyporeflective spotty lesions were observed on the Optos635-nm images, which coincided with hyperfluorescent dots on the ICGA images. The lesions gradually disappeared and the vortex vein became visible after treatment. The ultra-widefield Optos635-nm images processed by KagoEye3 software can exaggerate images of the choroidal vessels in widefield fundus images without using dye. Because this method is noninvasive, it is applicable to a variety of diseased and healthy eyes.