From the American Academy of Ophthalmology

This post-hoc analysis of a randomized trial comparing bevacizumab and laser therapy in diabetic macular edema shows that good long-term response is predicted by resolution of edema at four months. However, 20 percent of patients with persistent edema at 12 months achieved a dry macula and 50 percent gained more than 15 letters at 24 months with sustained treatment, suggesting that edema at four or 12 months should not be used as criterion for stopping treatment. Additionally, they found that eyes with better baseline visual acuity required fewer injections in the second year of treatment. British Journal of Ophthalmology, September 2013