Eylea can start to work within 3 months depending on the condition being treated. For some conditions, it may take up to 6 months before a significant difference is seen. Many trials only reported on results after 1 year of treatment and these report significant improvements in vision and the ability to read and see letters more clearly after this length of time for conditions such as Wet AMD, Diabetic macular edema, and diabetic retinopathy. Improvements in vision were maintained for the length of the trial (4 years in some instances).

For premature infants with retinopathy of prematurity (ROP), a leading cause of childhood blindness, Eylea may take up to 52 weeks to work. Two Phase 3 randomized trials FIREFLEYE (N=113) and BUTTERFLEYE (N=120) reported that approximately 80% of Eylea-treated infants achieved an absence of both active ROP and unfavorable structural outcomes after 52 weeks, which was significantly more than what would’ve been expected with placebo.

For diabetic macular edema specifically, 58% of patients had an improvement in their visual acuity measurements at 6 months compared to 6% in the control group. At one year, 80% of patients receiving Eylea improved compared to 15% in the control group. Patients in the Eylea groups gained, on average, the ability to read about two additional lines (15 more letters) on an eye chart compared with almost no change in the control group. In addition, those who received Eylea reduced the risk of continuing to a more serious stage of diabetic retinopathy.