Background/aims This study evaluated the impact of intravitreal injection of bevacizumab (IVB) on the microenvironment of the eyes of diabetic macular oedema (DMO) and macular oedema due to central retinal vein occlusion (CRVO-MO) patients.

Methods This study comprised 136 patients, including 51 patients in the DMO group, 70 in the CRVO-MO group and 15 in the control group, who were followed for 6 months after IVB. Angiogenic cytokines, inflammatory cytokines and growth factors concentrations in the aqueous humour were measured before and after IVB using suspension array technology. We compared the levels of cytokines among DMO patients, CRVO-MO patients and control patients. We compared the levels of cytokines among groups according to the interval between the first and second injections of bevacizumab and according to the number of injections received during the 6-month follow-up period.

Results Significantly higher concentrations of vascular endothelial growth factor (VEGF), transforming growth factor β (TGF-β), hepatocyte growth factor (HGF), interleukin 6 (IL-6), serum amyloid A (SAA) and monocyte chemoattractant protein-1 (MCP-1) were found in the aqueous humour of DMO and CRVO-MO patients compared with cataract patients. One month after IVB, the intraocular concentrations of VEGF were significantly decreased in the eyes of DMO (p=0.045) and CRVO-MO (p=0.002) patients compared with baseline. No other cytokine was significantly altered by bevacizumab therapy.

Conclusions Angiogenic, inflammatory and growth factors are involved in the development of DMO and CRVO-MO. In addition to VEGF, IVB did not cause significant differences in other inflammatory cytokines and growth factors in DMO and CRVO-MO patients.