The Causes Of Vitreous Hemorrhage In Diabetic Eyes Previously Treated With Panretinal Photocoagulation

Object: to study the pathogenesis of new vitreous hemorrhage ( VH ) in diabetics previously treated with panretinal photocoagulation (PRP) for diabetic retinopathy(DR).Methods: A total of 56 eyes of 56 patients (from the cases of Jul. 2006-Oct. 2008)undergoing PRP for diabetic retinopathy were enrolled in this study,except those who had not finished PRP for systemic or ocular reasons.All the patients` vision,and the examinations of slit lamp,indirect ophthalmoscopy and B-scan ultrasonograph were observed.The interval of time after PRP and the parameter of PRP were checked.A total of 28 patients underwent standard subtotal three-port pars plana vitrectomy because of vitreous hemorrhage .The conditions of posterior vitreous detachment (PVD) and retinal proliferate membranes were recorded,and the proliferate membranes got in the vitrectomy were given HE staining and immunohisto -chemical tests.Results:1 In all of the 56 cases,24 patients were male and 32 patients were female;the ages ranged from 50 to 71 ,and their courses of DR ranged from 1 year to 30 years.2 Before treated with PRP, there were 20 patients with preproliferative diabetic retinopathy (PPDR) and 36 patients with proliferative diabetic retinopathy (PDR);the wavelength of the laser was 531nm,the diameter of the spots were 200μm,the time of exposure was 0.2 seconds and the number of spots ranged from 1200 to 2300;the period between PRP and VH ranged from 3 months to 4 years;there were 3 patients developed VH after vitrectomy,including 1 patient who developed VH 3 times.3 According to the characteristics of B-scan ultrasonograph,37 patients were found partial PVD , and 25 patients developed VH ,the incidence of VH was 67.6%;19 patients were found total PVD, and 3 patients developed VH ,the incidence of VH was 15.8%..4 In all of the 28 patients who got vitrectomy, 3 were PPDR and 25 were PDR before PRP; according to the observation in the vitrectomy,24 patients were found partial PVD and 4 patients were found total PVD ;the bridge-like proliferate membranes were found in 11 patients,and the permeated retinal proliferate membranes were found in 14 patients; 23 patients got additional laser photocoagulation and 5 patients didn`t.The membranes which were red and bleeding while cutted were regarded as retinal neovascular membranes(13 cases);and the membranes which were white and not bleeding while cutted were regarded as retinal fibrous membrane(12 cases).5 The membranes got in the vitrectomy were taken pathological study: HE staining results showed that lots of small vessels and red blood cells were found in the retinal neovascular membranes,and atrophic vessels and few red blood cells were found in the retinal fibrous membranes; Immunohistochemical results showed that the expression of VEGF was high in the retinal neovascular membranes and low in the retinal fibrous membranes.6 According to the examination of indirect ophthalmoscopy and FFA or the observation in the vitrectomy, there were 41 cases that were found retinal proliferate membranes:13 patients were found bridge-like proliferate membranes,and 11 patients developed VH,the incidence of VH was 84.6%; 28 patients were found permeated proliferate membranes, and 14 patients developed VH,the incidence of VH was 50.0%. This difference was significant at the P<0.05 level.7 According to the examination of FFA and the observation in the vitrectomy,all cases were devided into two groups:19 patients were found retinal neovascularizations,and 13 patients developed VH,the incidence of VH was 68.4%;37 patients were not found retinal neovascularizations, and 15 patients developed VH,the incidence of VH was 40.5%. This difference was significant at the P<0.05 level.8 In the 28 patients who got vitrectomy,there were 19 cases(67.9%) whose visual acuity was improved,and 6 cases(21.4%) whose visual acuity was not improved obviously,and 3 cases(10.7%) last whose visual acuity dropped.Conclusions: 1 Partial PVD and bridge-like proliferate membranes are both significant reasons that can lead to vitreous hemorrhage in diabetic eyes previously treated with panretinal photocoagulation.2 The proliferation of neovascularization on retina and in the viteous body is the foundation of VH.3 The position and energy of the additional laser photocoagulation have connection with VH.4 The patients with risk factors of VH should be given vitrectomy in time.