fibrin and Macular-Degeneration

Some neovascular membranes comprise two parts: a fibro - vascular central body and an avascular marginal component. Certain authors have suggested that this avascular part could be involved in post laser treatment recurrence of subfoveal membranes. The purpose of this study was to determine the ultrastructural features of the marginal avascular component.. Four well-defined subfoveal neovascular membranes associated with age-related macular degeneration were surgically excised. The peripheral portion of each membrane was evaluated by transmission electron microscopy for cellular and extracellular constituents.. Each subretinal neovascular membrane was composed of two regions demonstrated by fluorescein angiography: a central area of hyperfluorescent leakage and an annular rim of hypofluorescence. The edge of the central body corresponded to a richly neovascularized tissue and was surfaced by a hyperplasic retinal pigmented epithelium. The rim was composed of a layer of retinal pigmented epithelium and a layer of photoreceptor outer segments associated with macrophages. The stroma was composed of fibrin and was avascular and acellular.. Neovascular removal of membrane was surgically removed as well as native retinal pigmented epithelium beyond the surface of fibrovascular central body which could explain why post operative scar surfaces were larger than to the initial preoperative membrane defined by fluorescein angiography.. The peripheral rim of neovascular membrane is an exsudative complication of the outer epithelium made up fibrin, native retinal pigmented epithelium, and photoreceptor outer segments. The front of the active neovascularization is localized in the periphery of the central fibrovascular body.

Topics: Choroidal Neovascularization; Fibrin; Fluorescein Angiography; Humans; Macular Degeneration; Microscopy, Electron; Photoreceptor Cells; Pigment Epithelium of Eye

The histopathologic features of ten consecutive surgically excised subfoveal neovascular membranes from patients with age-related macular degeneration were examined. Ultrastructural features included the following in decreasing order of frequency: endothelium-lined vascular channels, new collagen, fibrocytes, retinal pigment epithelium, erythrocytes, and myofibroblasts. Chronic inflammatory cells were frequently evident and included macrophages, lymphocytes, and plasma cells. Basal laminar deposit or diffuse drusen were observed in six of the membranes. Photoreceptors and Bruch's membrane were each observed in three of the specimens, but were not associated with decreased postoperative visual acuity. Fibrin was observed in eight membranes, either within the stroma of the membrane or in association with subretinal hemorrhage.

Topics: Age Factors; Collagen; Endothelium, Vascular; Fibrin; Fibroblasts; Humans; Macrophages; Macular Degeneration; Pigment Epithelium of Eye; Retinal Neovascularization