AIM: To investigate the effectiveness and safety of intravitreal injection of anti-vascular endothelial growth factors(VEGF)drugs to the patients with proliferative diabetic retinopathy before vitrectomy treatment.

METHODS: A Meta-analysis. A comprehensive retrieval was conducted using the database including EMbase, the Cochrane Library, Pubmed, CBM, WanFang Database, CNKI and so on. The retrieval time was limited from the building time of database to Jan. 2017. The randomized controlled trial was adopted with no requirements on languages. The Jadad scale and Cochrance cooperation were used as the tool of the risk and bias evaluation to analyze the literature quality. Quality estimation of evidence-based medicine on the parameters of each evaluation index was made via GRADEpro Software. The publishing biases of enclosed documents were inspected with funnel plot. At last, the Meta analysis was conducted with Review Manager 5.3.

RESULTS: Totally 16 literatures published from 2008-2016 were finally put into randomized controlled trial. A total of 923 cases were included, among which 493 cases were grouped as intravitreal injection of anti-VEGF before the combined operation of PPV group(the experimental group), and 430 cases were involved in simple PPV group(the control group). The results of Meta-analysis show:(1)The probability of intraoperative bleeding was remarkably lower than the control group \〖OR=0.06, 95%CI(0.02, 0.15), P<0.01\〗, with statistically significant differences.(2)The duration of operation was obviously shorter than that of the control group\〖WMD=-29.13, 95% CI(-36.95, -21.30), P<0.01\〗, with statistically significant differences.(3)The probabilities of both early and late postoperative vitreous hemorrhage were lower than those of the control group\〖OR=0.34, 95%CI(0.20, 0.58), P<0.01\〗, with highly statistically significant differences.(4)The best corrected visual acuity after surgery was no better than that of the control group, \〖WMD=-0.51(LogMAR), 95%CI(-1.10, 0.08), P=0.09\〗 with no statistical significance.(5)The occurrence of iatrogenic retinal rupture was lower than that of the control group\〖OR=0.24, 95%CI(0.14, 0.40), P<0.01\〗, with statistically significant differences.(6)Among the 493 patients included in the 16 literature, no case of ocular and general adverse effects due to anti-VEGF injections was reported.

CONCLUSION: It is effective and safe for the patients with proliferative diabetic retinopathy to inject anti-VEGF drugs into vitreous cavity before vitrectomy. And it can reduce the occurrence of complications during and after surgery, improving the general treatment effects. However, the specific implementation plans, such as the injection does, the interval between the injection and the operation and so on, still need further exploration and perfection.