Only a few histopathological cases of this type of membrane have been reported. 5 Subretinal membranes are composed of transdifferentiated RPE cells, glial cells, fibroblasts, myofibroblasts, and inflammatory cells. After retinal detachment, RPE can migrate to the outer retinal surface and differentiate into macrophages. 6-8 Retinal pigment epithelium may also transdifferentiate into cells histologically similar to a fibrocyte, capable of continuous multiplication and collagen synthesis. 9 Epithelial-like cells appear late in retinal detachment, resemble normal RPE cells, and do not appear to proliferate further.
Glial cells contribute to the formation of subretinal membranes.
Glial cells can migrate and proliferate through focal interruptions in the external limiting membrane of the retina. It is believed that glial cells are present in subretinal membranes only in long-standing retinal detachments. Myofibroblasts are cells with characteristic features of both fibroblasts and smooth muscle cells. Several studies reported the presence of myofibroblasts in PVR and proliferative diabetic retinopathy, and concluded that they might be responsible for vitreoretinal traction. This patient had a markedly folded and detached retina in a closed funnel-shaped configuration.