While there are many causes of macular degeneration, including genetic abnormalities such as Stargardt disease, age-related macular degeneration (AMD or ARMD) is by far the most common type. AMD is a disease associated with aging that gradually destroys sharp central vision that is needed for seeing objects clearly and for common daily tasks such as reading and driving. In some cases, AMD advances so slowly that people notice little change in their vision. In others, the disease progresses faster and may lead to a loss of vision in one or both eyes. AMD is the leading cause of vision loss in Americans 60 years of age and older. AMD usually affects both eyes, although the clinical appearance and degree of visual loss may vary a great deal between the two eyes.

AMD occurs in two forms. "Wet" age-related macular degeneration is less common but more aggressive in its progression to severe central vision loss. "Dry" age-related macular degeneration is the more common type and is more slowly progressive in causing visual loss.

AMD may be classified as to its severity using terms such as mild, moderate, or severe. These terms are subjective and not based on specific characteristics.