Quantitative Ultra-Widefield Imaging Measurement of Fundus Depigmentation in Vogt–Koyanagi–Harada Disease

Purpose To quantitatively assess the progression of fundus depigmentation in Vogt–Koyanagi–Harada (VKH) disease using ultra-widefield fundus photography (UWF-FP) and to investigate its relationship with inflammatory activity, treatment, and best-corrected visual acuity (BCVA).Methods This retrospective longitudinal cohort study included 28 eyes from 14 VKH patients followed for at least three years. UWF-FP images (Optos Silverstone) were analyzed using a custom ImageJ macro to calculate the percentage of choroidal depigmentation within a standardized rectangular region centered on the optic nerve head. Depigmentation values were correlated with BCVA (logMAR), cumulative inflammatory episodes, and baseline systemic therapy. Disease activity was defined according to the Standardization of Uveitis Nomenclature (SUN) criteria. Statistical analyses were performed using R software.Results The mean percentage of depigmentation increased from 10.47% ± 18.84% at baseline to 26.82% ± 28.63% at the last follow-up (mean 4.29 ± 1.78 years; p < 0.001). Greater cumulative inflammatory episodes were associated with steeper depigmentation progression (r = 0.73, p < 0.001). BCVA improved from 0.62 logMAR at baseline to 0.11 logMAR at last follow-up but showed a moderate positive correlation with depigmentation (r = 0.64), suggesting that structural changes persist despite visual recovery. Patients receiving combined corticosteroid–immunosuppressive therapy exhibited significantly slower depigmentation progression compared with corticosteroid monotherapy.Conclusion Quantitative assessment of fundus depigmentation using UWF-FP provides an objective imaging biomarker of disease progression in VKH. Depigmentation correlates with inflammatory burden and long-term visual outcome. Early initiation of combined therapy may limit depigmentation and improve disease control.