The effect of single dose adjunctive dexamethasone implant on diabetic macular edema in patients on anti-vascular endothelial growth factor treatment: 1 year follow-up from a real-life practice

Abstract

To evaluate the effect of single-dose intravitreal dexamethasone (Dx) implant as an adjunctive treatment for patients undergoing anti-vascular endothelial growth factor (anti-VEGF) treatment with poor response. Eighty-four eyes of 72 patients with non-proliferative diabetic retinopathy and diabetic macular edema with a poor response to 3 loading doses of intravitreal ranibizumab (IVR) were included in this study. Group 1 consisted of forty-four eyes which went on a Pro re Nata (PRN) dose regimen of IVR injections after 3 loading doses of ranibizumab, and Group 2 consisted of 40 eyes which received a single dose Dx implant as the 4th injection after 3 loading doses of ranibizumab injections and then went on PRN IVR injections. Patients whose macular edema was unchanged or decreased by<25% and gained three letters or less on the Early Treatment Diabetic Retinopathy Study visual acuity (VA) chart were defined as poorly responsive. Follow-up time was 12 months. After the 12-month follow-up, Group 1 gained a median of five letters, and Group 2 gained a median of three letters. After the fourth injection, both groups had statistically significant VA gains at 4, 6, 7, and 12 months when compared with controls (P<.05). Group 2 had a significantly increased VA at 4 and 6 months when compared with controls. However, beginning at 7 months, Group 1 had significantly increased VA when compared with Group 2. At both 4 and 6 months, controls (first 3 months after Dx implantation) in Group 2 had significantly decreased central macular thickness (CMT) when compared with Group 1. However, after 7 months, there was no significant difference between groups with regard to CMT (P>.05). A single-dose Dx implant after three consecutive IVR injections for poorly responsive diabetic macular edema has limited effect on either VA or CMT. The need for IVR injections did not decrease with a Dx implant.