Age-related macular degeneration (AMD) is the leading cause of severe vision loss in people aged 60 years and older. It is the central vision that is affected in AMD, so that, while severe visual impairment and legal blindness may result, some peripheral vision is generally preserved. Nonetheless, the central visual loss characteristic of AMD represents a major handicap to most affected individuals, seriously compromising many basic functions of everyday life including watching television, reading, driving, recognizing signs and faces, and doing close-up detail work, making its impact on vision-related quality of life potentially devastating. While the prognosis in AMD was bleak in the recent past, important advances in the understanding of the pathophysiology of AMD have led to a number of innovative new medical and surgical therapies, which can limit the progression of AMD in many of its victims and occasionally even restore vision.
As with cataract, AMD may be regarded as a pathological extension of what is essentially a normal consequence of the aging process in the eye. As is true with cataract, AMD transforms from an aging change to a disease when it progresses to the point where significant visual compromise or even blindness results. Macular degeneration is in essence a blanket term for many diseases, characterized by a tremendous range of macular pathology and associated visual loss.
There are 2 basic forms of AMD: wet and dry, with the former distinguished from the latter by a “wet” appearance to the macula, due to the accumulation of edema fluid, hemorrhage, and exudate. While the wet form of AMD is generally believed to be the more serious of the two, appearance does not necessarily correlate with visual function. In many cases of the so-called “dry” type of macular degeneration, subtle changes in macular pigmentation may translate into profound visual compromise.
Age-related Macular Degeneration
An estimated 25% of people aged 80 years and older suffer from serious, vision-threatening AMD. In a large epidemiologic study in the United States, the overall prevalence of AMD was 9%, with a prevalence rate of 2% in the youngest age group (age 52 to 64) and 28% in the oldest age group (age 75 to 85). Since both the prevalence and the severity of AMD increase with advancing age, with life expectancy lengthening, AMD is anticipated to become an ever greater public health problem in the 21st century.