Clinical and histological features of epiretinal membrane after diabetic vitrectomy

To investigate the clinical, histopathological, and surgical features of the epiretinal membrane (ERM) after diabetic vitrectomy (DV). From August 2007 to January 2010, clinical charts of consecutive proliferative diabetic retinopathy (PDR) cases with significant post-DV ERM, defined as thickened membrane causing macular distortion and vision decrease, were enrolled as the study group; PDR cases without post-DV ERM in 24 months follow-up served as the control group. Factors associated with post-DV ERM formation, morphological and visual changes before and after ERM surgery, and histopathological features were analyzed. Sixteen eyes were in the ERM group, while 60 eyes were in the control group. Active PDR (p < 0.001), fibrovascular proliferation (FVP) grade (p = 0.001), post-DV hemorrhage (p = 0.012), and residual fibrovascular stump (p = 0.002) were factors significantly associated with post-DV ERM. Most membranes (87.5 %) developed within 12 months, were widespread beyond the arcade (81.3 %), and connected with retinal vessels (87.5 %). After surgery, significant VA improvement was achieved. ERM recurrence was noted in six eyes (37.5 %). Histopathological examinations of ERMs in six cases showed abundant collagen fibers with epithelial cells. Immunohistochemical staining with CD 34 demonstrated the presence of vascular endothelium in two of the six specimens. The post-DV ERM is a complex tissue with variable vascularity that often presents with widespread distribution, rapid progression, and causes macular distortion. Associated risk factors include active PDR, high FVP grade, post-DV hemorrhage, and residual fibrovascular stumps. Membrane removal surgery may be beneficial in selected cases, but recurrence is not uncommon.