Effect of intravitreal conbercept injection on VEGF-A and -B levels in the aqueous and vitreous humor of patients with proliferative diabetic retinopathy

The present study aimed to investigate the mechanisms of anti-VEGF treatment prior to eye surgery to reduce intraoperative bleeding. A total of 30 patients with proliferative vitreoretinopathy after clinical diagnosis were enrolled in the present study as the surgical group. Furthermore, 30 patients underwent intravitreal injection of the anti-VEGF drug conbercept and were considered the drug pretreatment group. The aqueous and vitreous humors from the eyes of patients in the surgical group were drawn during pars plana vitrectomy surgery. The aqueous humor in the eyes of patients in the drug pretreatment group was drawn prior to conbercept treatment and seven days after conbercept treatment immediately prior to surgery. The vitreous humor in this group was only taken during surgery. Furthermore, ELISA was used to detect the levels of VEGF-A and -B in the aqueous and vitreous humors. Semi-quantitative determination of VEGF-A and VEGF-B levels in fibrovascular proliferative membranes was performed using immunohistochemical staining. The results indicated that in the drug group, the levels of VEGF-A in the aqueous humor of patients prior to and after conbercept injection were 197.66±48.00 and 3.39±2.54 pg/ml, respectively. The levels of VEGF-A in the vitreous humor of patients in the surgical and drug groups were 267.53±179.60 and 21.43±5.81 pg/ml after injection, respectively. The levels of VEGF-B in the aqueous humor of patients prior to and after conbercept injection were 13.66±3.30 (before injection) and 2.17±0.94 pg/ml (after injection), respectively. The levels of VEGF-B in the vitreous humor of patients in the surgical and drug groups were 127.36±16.72 and 18.56±9.82 pg/ml after injection, respectively (P<0.05). Furthermore, in the drug group, the surgery time, bleeding and capillary formation were significantly reduced compared with those in the surgical group. Taken together, these results suggested that the levels of VEGF-A and -B decreased significantly in the aqueous humor of patients with PDR after conbercept injection. Furthermore, the levels of VEGF-A and -B in the vitreous humor of patients dropped significantly in the drug group compared with those in the surgical group. These results provide theoretical clinical support for the preoperative application of conbercept for patients with PDR.