AIM: To evaluate theeffect of preoperative injection of Avastin at different time points for pars plana vitrectomy(PPV)in proliferative diabetic retinopathy(PDR)through clinical research and study the best proper time point for injection.

METHODS: We studied 49 patients(51 eyes)(from March 2010 to August 2012)with severe PDR. Sixteen cases(17 eyes)were treated with Avastin 4 days before PPV(group 1); 15 cases(16 eyes)were treated with Avastin 10 days before PPV(group 2); and 18 cases(18 eyes)underwent direct PPV(group 3). Surgical time, the condition of neovascular membranes, the number of iatrogenic retinal tear, and silicone oil utilization intra-operative, and vision after 6 months of surgery were recorded.

RESULTS: Compared to group 1(treated withAvastin, 4 days before PPV), group 2(treated with Avastin, 10 days before PPV)and group 3(simple vitrectomy surgery group), there were significantly difference. In group 1 and group 2, operative time was shortened, and interruption neovascular membranes bleeding rate, iatrogenic retinal tear rate and silicone oil utilization rate intra-operative were lower than the group 3, and the visual acuity was significantly better than the group 3. There was no statistically significant difference between group 1 and group 2 in surgical time, the condition of neovascular membranes, the number of iatrogenic retinal tear, and silicone oil utilization intra-operative, and vision 6 months after surgery.

CONCLUSION:Avastin administered prior to PPV was well tolerated, thus facilitating PPV, and to maximize the recovery of patients with limited vision. The ideal injection time of Avastin using for PPV in PDR is 4 days before PPV.