A hemodynamic model of the pathogenesis of age-related macular degeneration.

The clinical message of this editorial is that age-related macular degeneration may be a vascular disorder. It may be a manifestation of the hemodynamic consequence of the process of lipoid infiltration that, when it involves other organs such as those of the cardiovascular or cerebrovascular systems, is called atherosclerosis. The hemodynamic model presented here postulates that in age-related macular degeneration, the increase in resistance to the flow of blood in the choroid is caused by an age-related and diet-related decrease in the compliance of the sclera. It proposes that the form of age-related macular degeneration produced may depend on the relative resistances of the ophthalmic and cerebral circulations. A decrease in perfusion, leading to the atrophic form of age-related macular degeneration, is the outcome if the resistance of the cerebral circulation is relatively lower than that of choroid. Conversely, a relatively greater increase in the increase in the hydrostatic pressure in the choroidal vessels, leading to the exudative form of the disorder.