In every human eye various alterations occur with age at the level of the outer retina, the retinal pigment epithelium (RPE), Bruch’s membrane and the choroid. Several of these changes are thought to contribute to the pathogenesis of age-related macular degeneration (AMD), and are influenced by genetically and exogenous factors in this complex multifactorial disease (see Chap. 1). Epidemiological data indicate not only that there is an exponential increase in incidence of early late-stage disease beyond 50 years of age, but that possibly every human being would experience visual loss from this disease if they reached an age high enough for its manifestation, i.e. if life expectancy exceeded the current limits. Apparently, genetic and environmental factors determine whether the onset of disease is earlier or later in life.