OBJECTIVES: Geographic Atrophy (GA) affects eight million people worldwide, limits visual acuity (VA) resulting in blindness. Our aim was to forecast the long term impact of GA on visual loss and blindness, and the expected benefits of early treatment. METHODS: The model was developed using Excel Visual Basic Application (VBA) with the following inputs: 1) population characteristics (gender, age at GA diagnosis, baseline VA, one eye versus two eyes involvement), 2) health states by VA (no visual impairment, visual impairment, blindness and death), 3) rate of VA decline.  Data of natural progression of GA from Age-Related Eye Disease Study (AREDS) was used as the main input for this model.  The key outputs of the model under no intervention/hypothetical intervention are: 1) time to loss of functional vision (VA>20/40), visual impairment (VA<20/80), and blindness (VA≤20/200), and 2) time to event curves for visual disability and blindness. RESULTS: :  In a simulated cohort of 500 patients diagnosed with GA (with a mean age of 70 years and VA= 20/60), the model estimated that 60% of them would develop blindness in the affected eye over their lifetime without intervention.  On average, they experience four years with visual impairment and eight years with blindness. The model also showed that GA patients with younger age and worse VA at diagnosis, and faster rate of VA decline are at increased risk of attaining blindness.  A hypothetical intervention with 25% and 50% efficacy avoided 1 and 3 years of blindness, respectively. Sensitivity analysis showed that  treatment efficacy when compared to starting age, starting VA, and rate of VA loss, had the highest impact in reducing time spent in blindness. CONCLUSIONS: The simulation model based on natural history of GA progression showed that effective treatment started early at diagnosis can reduce the burden of vision loss among GA patients.