Purpose: Estimate effects of ranibizumab on diabetic retinopathy (DR) severity in US Hispanic and non-Hispanic white persons with center-involved diabetic macular edema (DME) causing vision impairment for whom ranibizumab treatment would be considered., Patients and Methods: This model simulated DR severity outcomes over 2 years in the better-seeing eye using US census, National Health and Nutrition Examination Survey, Wisconsin Epidemiologic Study of Diabetic Retinopathy, and Los Angeles Latino Eye Study data. Baseline DR severity estimated from Diabetic Retinopathy Clinical Research Network trial data. Changes in DR severity after 2 years, with/without monthly ranibizumab (0.3 or 0.5 mg), were estimated from Phase III clinical trial data (RIDE/RISE) using a 2-dimensional Monte Carlo simulation model. Number of patients over a 2-year period for whom 1) DR severity worsening was avoided, 2) DR severity improved, and 3) selected clinical events related to proliferative DR (PDR) occurred, was estimated., Results: An estimated 37,274 US Hispanic and non-Hispanic white persons were projected to have DR with center-involved DME and be eligible for ranibizumab treatment. The number of persons with moderately severe non-proliferative DR (NPDR) or less severe DR at baseline who would worsen to PDR and experience a PDR complication over 2 years would be reduced from 437 with no ranibizumab to 19 with ranibizumab (95% reduction; 95% simulation interval [SI], 79-100%). The number of persons with severe NPDR or less severe DR at baseline who would be expected to improve by ≥2 DR severity levels over 2 years would increase from 1706 with no ranibizumab to 13,042 with ranibizumab (682% increase; 95% SI, 478-967%)., Conclusion: This model estimates that ranibizumab treatment in US Hispanic and non-Hispanic white patients with center-involved DME causing vision impairment would potentially reduce the number of patients with worsening DR and potentially increase the number with DR improvements., Competing Interests: RV is a consultant for Aerie (Irvine, CA, USA), Allergan (Irvine, CA, USA), Aquesys (Aliso Viejo, CA, USA), Bausch + Lomb (Rochester, NY, USA), and Genentech, Inc. (South San Francisco, CA, USA); and has received an unrestricted departmental grant from Research to Prevent Blindness (New York, NY, USA). NMB is principal investigator of grants at Johns Hopkins University; grants to investigators at Johns Hopkins University are negotiated and administered by the School of Medicine, which receives the grants through the Office of Research Administration. Individual investigators who participate in sponsored projects are not directly compensated by the sponsor, but may receive salary or other support from the institution to support their effort on the projects. He also has an independent contract agreement at Johns Hopkins University with the American Medical Association (Chicago, IL, USA). He is also sponsored by Bayer (Wayne, NJ, USA), Genentech, Inc./Roche (South San Francisco, CA, USA), the National Institutes of Health (Bethesda, MD, USA), Novartis Pharma AG (Basel, Switzerland), and Samsung Bioepis (Seoul, Korea). QVD is an employee of Outcomes Insights, Inc. (Westlake Village, CA, USA); and consultant for and reports grants from Genentech, Inc. (South San Francisco, CA, USA). IJS is a consultant for Genentech, Inc. (South San Francisco, CA, USA), Optos (Dunfermline, UK), Pfizer (New York, NY, USA), and Regeneron (Tarrytown, NY, USA); has received financial support from Genentech, Inc. (South San Francisco, CA, USA); and been on the medical advisory board for Optos (Dunfermline, Scotland). MD is an employee of Outcomes Insights, Inc. (Westlake Village, CA, USA); and consultant for and reports grants from Genentech, Inc. (South San Francisco, CA, USA). CMD is a consultant for Genentech, Inc. (South San Francisco, CA, USA), Gilead (Foster City, CA, USA), Myokardia, Inc., Iconic Therapeutics (South San Francisco, CA, USA), Portola Pharmaceuticals, Inc. (South San Francisco, CA, USA), Relypsa (Redwood City, CA, USA), Halozyme (San Diego, CA, USA), and Regenxbio (Rockville, MD, USA). AL is an employee of Outcomes Insights, Inc. (Westlake Village, CA, USA); and consultant for Genentech, Inc. (South San Francisco, CA, USA). JSE was an employee of Genentech, Inc. (South San Francisco, CA, USA) at the time of the study; and holds stock/stock options in the Roche Group (Basel, Switzerland); currently an employee of Kodiak Sciences Inc (Palo Alto, CA, USA). YR is an employee of Genentech, Inc. (South San Francisco, CA, USA); and holds stock/stock options in the Roche Group (Basel, Switzerland). The authors report no other conflicts of interest in this work., (© 2020 Varma et al.)