Transmission electron microscopic study of a subretinal choroidal neovascular membrane due to age-related macular degeneration.

From a patient with age-related macular degeneration we studied ultrastructurally a disciform scar that was removed from an eye with a vitreous hemorrhage. In cross section, the scar was divided by a retinal pigment epithelial (RPE) cell layer. The choroidal side consisted of fibrovascular tissue with active neovascular buds and inflammatory cells, including macrophages attached to the RPE basement membrane. Apart from the RPE, no components of Bruch's membrane could be identified. The retinal side contained organizing hemorrhage and a collagenous matrix with fibroblastlike cells probably of RPE and choroidal origin. The anatomy and the clinical findings at surgery suggest that such scars lie on (rather than within) the inner collagenous layer of Bruch's membrane and contain two components divided by the original RPE layer. The choroidal side is fibrovascular, including active neovascularization, and the retinal side is fibrous and formed by metaplastic RPE cells and choroidal fibrovascular ingrowth.