ObjectiveTo observe the effect of microincision vitrectomy assisted with intravitreaI injection of ranibizumab (IVR) in proliferative diabetic retinopathy (PDR) treatment. MethodsThis is a prospective, randomized, and comparative case series study. A total of 92 patients (92 eyes) with PDR were recruited to have microincision vitrectomy with (combined group) or without (PPV group) IVR. There are 48 eyes in the combined group and 44 eyes in the PPV group. The average operation time, iatrogenic breaks, the use of tamponade and electric coagulation, postoperative bleeding and best corrected visual acuity were comparatively analyzed among the two groups.The mean follow-up was (14.3±5.2) months. ResultsThe average operation time was (59.4±18.5) min in the combined group and (74.6±16.2) min in the PPV group. The rate of silicone oil tamponade (χ2=4.619), inert gas tamponade (χ2=4.290), electric coagulation (χ2=8.039) and iatrogenic breaks (χ2=4.330) in the combined group were significantly decreased compared with PPV group(P<0.05). The mean logMAR BCVA was 0.83±0.44 in the combined group and 1.37±0.53 in the PPV group, which significantly improved from preoperatively (t=3.257, 3.012; P<0.05). The rate of BCVA improvement in the combined group was significantly higher than that in the PPV group (t=2.972, P<0.05). The incidence of the recurrent vitreous hemorrhage was 2.1% in the combined group and 9.1% in the PPV group (χ2=6.741, P<0.05). There was no severe complication associated with surgery, such as choroidal detachment, retinal detachment and endophthal-mitis. ConclusionIVR before the microincision vitrectomy can shorten the operation time, reduce the use of electric coagulation and intraocular tamponade, and improve visual acuity for PDR patients.