[Ultrastructural features of peripheral choroidal neovascular membranes in age-related macular degeneration].

PURPOSE

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.

METHODS

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.

RESULTS

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.

DISCUSSION

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.

CONCLUSIONS

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.