Effect of Adjunctive Intravitreal Conbercept Injection at the End of 25G Vitrectomy on Severe Proliferative Diabetic Retinopathy: 6-Month Outcomes of a Randomised Controlled Trial

INTRODUCTION: This study aimed to evaluate the effect of pre-operative versus pre-operative plus post-operative intravitreal conbercept (IVC) injection on severe proliferative diabetic retinopathy (PDR). METHODS: This was a prospective, comparative and randomised study. A total of 84 patients who underwent vitrectomy for severe PDR were included in this study. Patients were randomly divided into control (41 eyes) and experiment (43 eyes) groups. Patients in the experiment group received adjunctive pre-operative and post-operative IVC injection, whereas patients in the control group only received pre-operative IVC injection. The incidence of post-operative vitreous haemorrhage (POVH), best-corrected visual acuity (BCVA) and central retinal thickness (CRT) were determined. RESULTS: The incidence of early POVH was significantly different between the two groups, but no significant difference was observed between groups at 3 and 6 months. In the experiment group, the BCVA was significantly improved 1 month after surgery when compared with the control group (p 0.019). There was no marked difference in the mean post-operative BCVA at 3 and 6 months between groups (p 0.063 and 0.082). CRT was significantly lower in the experiment group than in the control group at 1 and 3 months after surgery (p 0.037 and 0.041), but there was no significant difference at 6 months (p 0.894). CONCLUSION: Additional IVC injected at the end of surgery improves the POVH and BCVA at the early stage after surgery in severe PDR, but this benefit is absent at 6 months. Further studies are needed to investigate the effect of IVC at the end of vitrectomy. TRIAL REGISTRATION: chictr.org.cn identifier: ChiCTR2200060735. Retrospectively registered, register date: 9 June 2022.