Related factors of postvitrectomy vitreous hemorrhage in proliferative diabetic retinopathy

Background Vitrectomy is an effective method to proliferative diabetic retinopathy (PDR) in type 2 diabetic patients.Postoperative vitreous hemorrhage is a major cause of vision loss.Objective This study was to analyze the related factors of vitreous hemorrhage after vitrectomy in proliferative retinopathy with type 2 diabetes.Methods Three hundred and five eyes of 305 cases who received vitrectomy for PDR from type 2 diabetes were retrospectively investigated.The clinical data of 14 eyes with vitreous hemorrhage after vitrectomy were analyzed.Results Vitreous hemorrhage after vitrectomy occurred in 14 eyes with the incidence 4.6％.The PDR was grade ⅣV in 3 eyes,grade Ⅴ in 4 eyes and grade Ⅵ in 7 eyes.Pars plana vitrectomy with intraocular laser photocoagulation was performed on all the 14 eyes,and 1 eye accepted scleral condensation and 8 eyes accepted silicone oil tamponade.Visual acuity was improved in 6 eyes,unchanged in 4 eyes and worsen in 4 eyes after initial surgery.Vitreous hemorrhage appeared in postoperative 1-7 days in 9 eyes,8 days-3 months in 1 eye,3-6 months in 2 eyes and over 6 months in 2 eyes.The cause for postoperative vitreous hemorrhage included residual neovascular membrane,insufficient photocoagulation range and intensity,neovascularization and instable blood glucose level.Vitreous hemorrhage disappeared in 5 eyes after medicine therapy,and reoperation in 9 eyes.In the end of the follow up,visual acuity improved in 9 eyes,unchanged in 2 eyes and worsen in 3 eyes.Retinas reattached in 13 eyes.However,the retina was still detached in 1 eye with silicone oil tamponade.Conclusions Postoperative vitreous hemorrhage usually occurs within 1 week.The main related factors are residual retinal neovascular membrane,inadequate intraocular laser photocoagulation and unstable blood glucose level.Medicine therapy is effective for postoperative vitreous hemorrhage in type 2 diabetic patients,but re-vitrectomy is needed for excessive vitreous bleeding. Key words: Diabetes mellitus/complication;  Proliferative;  Retinopathy/treatment, surgery;  Vitrectomy;  Postoperative vitreous hemorrhage