The ultrastructural features of three surgically excised idiopathic su
bfoveal neovascular membranes were examined. Ultrastructural features
of the cellular components in the membranes included retinal pigment e
pithelium, endothelial-lined vascular channels, photoreceptor cells, m
acrophages, myofibroblasts, glial cells, erythrocytes, and ghost eryth
rocytes. Extracellular constituents included 200-nm to 250-nm collagen
fibrils, 100-nm collagen fibrils and fibrin. The findings in this stu
dy are consistent with previously reported findings of subfoveal neova
scular membranes in age-related macular degeneration and the ocular hi
stoplasmosis syndrome, with the exception of the presence of basal lam
inar deposit in membranes from age-related macular degeneration.