The progression of Stargardt Disease as determined by fundus autofluorescence over a 24-month period (ProgStar Report No. 17)

PURPOSE: To estimate the progression rate of atrophic lesions in Stargardt disease derived from fundus autofluorecence (FAF). DESIGN: International, multicenter, prospective cohort study. METHODS: 259 participants aged ≥6 years with disease-causing variants in the ABCA4 gene, were enrolled from nine centers and followed over a 24 month period. FAF images were obtained every 6 months and areas of definitely decreased autofluorescence (DDAF) and decreased autofluorescence (DAF) were quantified. Progression rates were estimated from linear mixed models with time as the independent variable. RESULTS: 488 study eyes of 259 participants (88.8% with both eyes) were enrolled and images from 432 eyes were followed for 24-months. The overall estimated progression of DDAF was 0.74 (confidence interval (CI) 0.64 - 0.85; p<.0001) mm2/year, and of DAF was 0.64 (CI 0.57 - 0.71) mm2/year over a 24 month period in univariate analysis. Growth rates were strongly dependent on baseline lesion area. After square root transformation, DDAF growth rate was not dependent on baseline lesion radius (p=0.11), whereas DAF growth rate was dependent (p<.0001). Genotype was not found to significantly impact growth rate of DDAF or DAF lesions. CONCLUSIONS: FAF may serve as a convenient monitoring tool and suitable endpoint for interventional clinical trials that aim to slow disease progression. DDAF and DAF lesion sizes at baseline are strong predicting factors for lesion area growth and can be partially accounted for by square root transformation