Persistent or recurrent vitreous hemorrhage after vitrectomy for diabetic retinopathy complications is a common occurrence with an incidence of 12% to 63%. This complication may prolong vitreous clear-up and delay visual rehabilitation significantly, and sometimes requires additional procedures or surgery.

The causes of bleeding are diverse. Evidence suggests fibrovascular proliferation from the sclerotomy sites or from the vitreous base may be an important source of recurrent vitreous hemorrhage; other sources of bleeding include iatrogenic intraoperative injury of retinal vessels, and incomplete removal of fibrovascular tissues.

We have reported on the possible benefit of peripheral retinal cryotherapy and cryotherapy treatment of sclerotomy sites to prevent delayed-onset recurrent vitreous hemorrhage, and the possible benefit of intravitreal long-acting gas to reduce the occurrence of early postoperative recurrent vitreous hemorrhage, especially for cases with active fibrovascular proliferation. However, minor recurrent vitreous hemorrhage and prolonged reabsorption of lysed blood clots from surgical trauma remain important factors to cause media opacity long enough to prevent quick visual rehabilitation.

Intravitreal bevacizumab has been noted to induce rapid regression of retinal and iris neovascularization in proliferative diabetic retinopathy. Further, presurgical administration of intravitreal bevacizumab may reduce intraoperative bleeding during membrane dissection in PDR with traction retinal detachment. We hypothesize that presurgical treatment of intravitreal bevacizumab may reduce intraoperative bleeding and the amount of residual blood clots, while intraoperative infusion of long-acting gas may facilitate post-operative recovery of surgically injured retinal vessels. These combined effects would thus enhance early clear-up of vitreous opacity from clot lysis and recurrent retinal bleeding. To investigate this hypothesis, a clinical prospective study was undertaken to evaluate the effects of bevacizumab pretreatment combined with intravitreal infusion of long-acting gas on the clearance speed and the recurrence rate of early postoperative vitreous hemorrhage in vitrectomy for active diabetic fibrovascular proliferation.