Chorioretinal juncture. Vascularization of Bruch's membrane in peripheral fundus.

Pathologic changes in chorioretinal juncture (pigment epithelium, drusen, Bruch's membrane, and choriocapillaris) were studied in the peripheral fundus of eyes removed at autopsy and surgically enucleated eyes by gross, light microscopic, and electron microscopic methods. Vascularization of Bruch's membrane (VBM) occurred in 430 (43%) of eyes at autopsy, was age related, and was most common in the ora zone and temporal sectors; a significant correlation was found with systemic oligemic conditions. Vascularization of Bruch's membrane occurs in the inner collagenous layer of the membrane, which always demonstrates collagenous thickening and often shows intrusion of interstitial-type cells; the vessels emanate from adjacent pars plana. While many degenerative changes of the pigment epithelium accompany VBM, only direct ophthalmoscopic visualization of linear-dendritic depigmentation of overlying pigment epithelium provides diagnostic evidence of vessels. Thus, VBM seems pathogenically related to the fact that the peripheral fundus is a vascular watershed and is selectively vulnerable to senile involutional changes.