ObjectiveTo observe the concentration of the inflammatory cytokines in vitreous of severe proliferative diabetic retinopathy (PDR) after intravitreal ranibizumab injection (IVR). MethodsA total of 80 PDR patients (80 eyes) were enrolled in this study. The patients were randomly divided into vitrectomy group (group A) and IVR combined with vitrectomy group (group B), 40 eyes in each group. The differences of sex (χ2=0.05), age (t=0.59), duration of diabetes (t=0.36), HbA1c (t=0.13) and intraocular pressure (F=0.81) between two groups were not significant (P>0.05). The eyes in group B received 0.5 mg (0.05 ml) ranibizumab injection at 7 days before operation. The vitreous samples (0.4 ml) were obtained before operation. The concentration of vascular endothelial growth factor (VEGF), interleukin (IL)-6, IL-8, intercellular adhesion molecule-1 (ICAM-1) and connective tissue growth factor (CTGF) were measured by enzyme-linked immunosorbent assays. ResultsThe concentration of VEGF and ICAM-1 were (10.70±3.60), (224.64±90.32) pg/L in group B and (72.38±23.59), (665.61±203.34) pg/L in group A. The differences of VEGF and ICAM-1 concentration between two groups was significant (t=16.34, 12.53; P<0.001). The concentration of IL-6 and IL-8 were (210.64±80.27), (156.00±57.74) pg/L in group B and (45.78±33.82), (41.07±13.82) pg/L in group A. The differences of IL-6 and IL-8 concentration between two groups was significant (t=11.97, 12.24; P<0.001). There was no difference of CTGF concentration between two groups (t=1.39, P=0.17). The CTGF/VEGF in group B was higher than that in group A (t=14.75, P<0.001). ConclusionsOne week after IVR, the concentration of VEGF and ICAM-1 are decreased, while IL-6 and IL-8 increased. There is no obvious change in CTGF, but CTGF/VEGF is increased.