AMD can be divided into 3 stages: early, intermediate, and late, based partially on the extent (size and number) of drusen.AMD-like pathology begins with small yellow deposits (drusen) in the macula, between the retinal pigment epithelium and the underlying choroid. Most people with these early changes (referred to as age-related maculopathy) still have good vision. People with drusen may or may not develop AMD. In fact, the majority of people over age 60 have drusen with no adverse effects. The risk of developing symptoms is higher when the drusen are large and numerous, and associated with the disturbance in the pigmented cell layer under the macula. Large and soft drusen are thought to be related to elevated cholesterol deposits. Early AMD
Early AMD is diagnosed based on the presence of medium-sized drusen, about the width of an average human hair. Early AMD is usually asymptomatic. Intermediate AMD
Intermediate AMD is diagnosed by large drusen and/or any retinal pigment abnormalities. Intermediate AMD may cause some vision loss, but, like early AMD, it is usually asymptomatic.Recently, subgroups of intermediate AMD have been identified, which have a very high risk of progression toward late AMD. This subgroup (depending on the precise definitions) is termed nascent GA and/or iRORA (incomplete retinal pigment epithelium and outer retinal atrophy). These high-risk subgroups of intermediate AMD can be used to inform patients of theirs prognosis. In addition, these can be applied in clinical trials as endpoints.
Late AMD
In late AMD, enough retinal damage occurs that, in addition to drusen, people will also begin to experience symptomatic central vision loss. The damage can either be the development of atrophy or the onset of neovascular disease. Late AMD is further divided into two subtypes based on the types of damage: Geographic atrophy and Wet AMD (also called Neovascular AMD). Dry AMD
Dry AMD (also called nonexudative AMD) is a broad designation, encompassing all forms of AMD that are not neovascular (wet AMD). This includes early and intermediate forms of AMD, as well as the advanced form of dry AMD known as geographic atrophy. Dry AMD patients tend to have minimal symptoms in the earlier stages; visual function loss occurs more often if the condition advances to geographic atrophy. Dry AMD accounts for 80–90% of cases and tends to progress slowly. In 10–20% of people, dry AMD progresses to the wet type. Geographic atrophy
Geographic atrophy (also called atrophic AMD) is an advanced form of AMD in which progressive and irreversible loss of retinal cells leads to a loss of visual function. There are multiple layers that make up the retina, and in geographic atrophy, there are three specific layers that undergo atrophy: the choriocapillaris, retinal pigment epithelium, and the overlying photoreceptors. The three layers that undergo atrophy in geographic atrophy are all adjacent to each other.