Interferon alpha-2b addition to intravitreal bevacizumab for diabetic macular edema: a randomized controlled trial

Intravitreal anti-vascular endothelial growth factor (anti-VEGF) agents are the standard of care in DME, a sight-threatening complication of diabetic retinopathy. However, many patients show suboptimal response to anti-VEGF agents alone. This study aimed to investigate the effect of adding interferon alpha 2b eye drops to intravitreal bevacizumab (IVB) in treating patients with DME.

In this double-blind, placebo-controlled, parallel clinical trial, eligible eyes of DME patients were randomized into two treatment arms: (1) three monthly doses of intravitreal bevacizumab (IVB) (2) three monthly doses of IVB plus interferon alpha 2b eye drops (IVB + IFN). Outcome measures were changes in central macular thickness (CMT) and best corrected visual acuity (BCVA) over four months. Intraocular pressure (IOP) and possible adverse events were also documented.

A total of 87 eyes of 87 patients with DME were included (mean age: 64.1, female-to-male ratio ~ 1:1). Anatomical and visual improvements were significant in both groups (p-value < 0.001). CMT reduction and BCVA improvement were greater in the IVB + IFN compared to the IVB group (-117 μm vs. -54 μm, 0.2 vs. 0.1 LogMAR, p-values = 0.004 and < 0.001, respectively). Final IOP was lower in the IVB + IFN group (p value = 0.02), but within groups changes were not significant in either arm (p-value > 0.05). No serious side effects associated with IFN alpha 2b were observed.

Adjunction of topical IFN alpha 2b to standard IVB therapy may result in superior functional and structural improvements in eyes with DME in short-term follow-up.

Iranian Registry of Clinical Trials (irct.behdasht.gov.ir), IRCT20230103057035N1, March 18th, 2023.