ABSTRACT
Epiretinal membranes [ERMs] are the result of cellular proliferation and connective tissue formation on the surface of the retina. It is the main histopathologic attribute of proliferative vitreoretinopathy [PVR] secondary to rhegmatogenous retinal detachment. Attempts have been made to determine the origin of cells in the membranes by using light microscopy and immunocytochemical criteria. The present study aimed at studying the histopathology of the epiretinal and subretinal membranes and immunohistochemical determination of the character of cells forming these membrane using pancytokeratin, Glial fibrillary acid protein [GFAP] and vimentin. The assessment of the cellular proliferative activity of these membranes using ki67 was also performed. The study included 18 epiretinal [90%] and 2 subretinal [10%] membranes. Immunohistochemical study using Pancyokeratin, Vimentin, and GFAP revealed positivity in 70%, 50%, and 50% of the studied membranes respectively. A statistical significant relation was detected between short duration of illness on one hand and Pancytokeratin positivity and moderate and high ki67 positivity on the other hand.[t=69.377, 1.927, P=0.000, 0.048 respectively].Another statistical significant relation was detected between 2+ or 3+ positivity of ki67 and Pancytokeratin positivity. [X[2] = 6.70, P= 0.018]. In conclusion, it is generally believed that ERMs secondary to PVR are formed mainly of epithelial cells, admixed with glial and mesenchymal cells. Detection of epithelial cells with high or moderate proliferative activity was more in patients with short history of disease