ObjectiveTo compare the outcomes of 23G and 25G plus (25G+) vitrectomy in treatment of proliferative diabetic retinopathy (PDR). MethodsThis is a prospective randomized study. Fifty-seven PDR patients (75 eyes) with symptoms requiring vitrectomy were randomly divided into 23G vitrectomy group (30 patients, 39 eyes) and 25G+ vitrectomy group (27 patients, 36 eyes). Visual acuity, intraocular pressures, ophthalmoscopy, B-scan ultrasound was examined before surgery. The follow-up period was 10.0 (23G group) and 8.5 months (25G+ group) respectively. Intraoperative complications, operation time, postoperative visual acuity, intraocular pressure, postoperative complications and postoperative ocular conditions were analyzed. ResultsThe mean surgical times were (53.35±7.42) minutes and (49.16±5.17) minutes in 23G and 25G+ group respectively, and the difference was significant (t=4.37, P < 0.05). Iatrogenic injuries occurred in 11 eyes (28.21%) and 5 (13.89%) eyes in 23G and 25G+ group respectively, and the difference was significant (χ2=4.93, P < 0.05). The postoperative visual acuity of 23G and 25G+ group were improved compared to before surgery (χ2=16.81, 18.29; P < 0.05). At last follow-up, there was 25 eyes and 24 eyes with visual acuity≥0.05 in 23G and 25G+ groups respectively, and the difference was not significant (χ2=0.13, P > 0.05). Hypotony was detected in 7 and 3 eyes at the third postoperative day in 23G and 25G+ group respectively, and the difference was significant (χ2=5.67, P < 0.05). Conclusion25G+ vitrectomy is a safe and effective treatment for PDR with shorter surgery time and fewer surgical complications.