November 1997 issue of the American Journal of Ophthalmology, I proposed that age-related macular degeneration is a vascular disorder, the hemodynamic sequela of atherosclerotic changes affecting the eye. New information regarding the nature and source of the lipids in Bruch membrane and in drusen prompts refinement of the hypothesis.

Arteriosclerosis refers to the group of disorders that have in common thickening and loss of elasticity of the arterial wall. It is so universal as to be considered part of “normal” aging. Atherosclerosis, the most common form of arteriosclerosis, is less universal, and is influenced by genetic, dietary, and other environmental factors. It is characterized by lipid deposition (the atherotic component) and vessel stiffening (the sclerotic component). 2 The deposition of lipid involves the extracellular trapping of small lipid particles enriched in cholesterol esters in the intima of large arteries. 3 The resulting loss of elasticity is caused by increased lesion collagen and destruction of medial elastin. The hemodynamic model, proposed earlier, 1 is revised and designated the vascular model (Figure 1), to reflect the roles proposed for both structural and hemodynamic factors in the pathogenesis of age-related macular degeneration.