AMD Stages & DEfinition

WHAT IS AMD

AMD is a progressive and degenerative disease affecting the central part of the retina, the macula.

Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss in the United States. Its prevalence is increasing with the growth of our aging population. In the U.S., over 11 million people suffer from AMD (1.75 million individuals have advanced forms of AMD). The worldwide prevalence of AMD is estimated to be at 196 million people and is estimated to increase to 288 million by 2040.

The macula is a structure in your retina that is responsible for central vision (i.e. sharp vision). Your central vision is critical in activities such as driving and reading which requires sharp vision to see fine details clearly. Vision loss caused by AMD typically starts with a blurred area near the central part of your vision. Over some period of time, the blurred spot may grow larger or you may develop blank spots in your central vision. Also, objects may not appear to be as bright as they once were. Age-related macular degeneration progresses at different rates in people. Some have AMD progress so slowly that vision loss does not occur for a longer period of time. In others, AMD may progress quickly to lead to vision loss in one or both eyes.

While the visual impact associated with early and intermediate macular degeneration stages can be minimal, some affected individuals progress to advanced disease. These advanced subtypes of geographic atrophy (GA) and neovascular disease (NV) are commonly associated with visual impairment and blindness, affecting quality of life and leading to loss of independence.

EARLY AMD

Early AMD. Early age-related macular degeneration stage is diagnosed by the presence of medium-sized drusen, which are about the width of an average human hair. An AMD risk test can help people determine whether to expect age-related macular degeneration. People with early AMD typically do not have vision loss.

INTERMEDIATE AMD

Intermediate Macular Degeneration Stage. People with intermediate AMD typically have large drusen, pigment changes in the retina, or both. Again, these changes can only be detected during an eye exam. Intermediate AMD may cause some vision loss, but most people will not experience any symptoms.

Late AMD. In addition to drusen, people with late AMD have vision loss from damage to the macula.

There are two types of late AMD:
In geographic atrophy (also called dry macular degeneration), there is a gradual breakdown of the light-sensitive cells in the macula that convey visual information to the brain, and of the supporting tissue beneath the macula. These changes cause vision loss.

In neovascular AMD (also called wet macular degeneration), abnormal blood vessels grow underneath the retina. (“Neovascular” literally means “new vessels.”) These vessels can leak fluid and blood, which may lead to swelling and damage of the macula. The damage may be rapid and severe, unlike the more gradual course of geographic atrophy. It is possible to have both geographic atrophy and neovascular AMD in the same eye, and either condition can appear first.