Abstract
Abstract: :
Purpose: The observation that age–related macular degeneration (AMD) and atherosclerosis share risk factors and pathogenetic mechanisms has led to the development of the Vascular Model of AMD. It holds that AMD is a vascular disorder, caused by a decrease in compliance of ocular tissues and characterized by impairment of choroidal perfusion of the retinal pigment epithelium. The model proposes that lipoproteins secreted by the retinal pigment epithelium accumulate in drusen and in Bruch's membrane (the dry form of AMD) because the choriocapillaris does not clear them. It also proposes that the combination of elevated intravascular pressure, Vascular Endothelial Growth Factor and calcification and fracture of Bruch's membrane is responsible for the development of choroidal neovascularization, (the wet form of AMD). Methods:Theoretical models of disease are evaluated by how much they explain and by their success in developing testable hypotheses. The Vascular Model is consistent with most of what we know of AMD and, by emphasizing the pathogenetic importance of atherosclerotic processes and increased intravascular pressure, essentially predicts that statins and anti–hypertensive agents should have a protective effect on AMD. Results:Preliminary studies suggest that statins and hypertensives may lower the risk of AMD. Conclusions: These reports are sufficiently promising to warrant adequately designed and properly executed clinical trials.Confirmation of the protective effect of statins or anti–hypertensives will lendfurther support to the Vascular Model.
Keywords: age–related macular degeneration • blood supply • choroid