An anti-VEGF therapy for DME improved vision by more than 15 letters in approximately 36-51% of participants in a trial.
Brown D, Nguyen Q, Marcus D, Boyer D, et al. Long-Term Outcomes of Ranibizumab Therapy for Diabetic Macular Edema: The 36-month results from two phase III trials: RISE and RIDE. Ophthalmol. 2013. http://www.aaojournal.org/article/S0161-6420(13)00212-1/abstract. Accessed May 17, 2016
Nearly 50% of DME patients who received an anti-VEGF drug, experienced substantial visual improvement after a year of injections.