ESSENTIALS OF DIAGNOSIS
Older age group.
Acute or chronic deterioration of central vision in one or both eyes.
Distortion or abnormal size of images in one or both eyes, sometimes developing acutely.
No pain or redness.
Macular abnormalities seen by ophthalmoscopy.
In developed countries, age-related macular degeneration is the leading cause of permanent visual loss in the older population. Its prevalence progressively increases over age 50 years (to almost 30% by age 75). Its occurrence and response to treatment are likely influenced by genetically determined variations, many of which involve the complement pathway. Other associated factors are race (usually white), sex (slight female predominance), family history, hypertension, hypercholesterolemia, cardiovascular disease, farsightedness, light iris color, and cigarette smoking (the most readily modifiable risk factor).
Age-related macular degeneration is classified into dry (“atrophic,” “geographic”) and wet (“neovascular,” “exudative”). Although both are progressive and usually bilateral, they differ in manifestations, prognosis, and management.
The precursor to age-related macular degeneration is age-related maculopathy that is characterized by retinal drusen (eFigure 7–42). Hard drusen appear ophthalmoscopically as discrete yellow subretinal deposits. Soft drusen are larger, paler, and less distinct. Large, confluent soft drusen are risk factors for neovascular (wet) age-related macular degeneration. Age-related macular degeneration results in loss of central vision only in most patients. Peripheral fields, and hence navigational vision, are maintained, except in patients with severe neovascular age-related macular degeneration.
“Dry” age-related macular degeneration is characterized by gradually progressive bilateral visual loss due to atrophy of the outer retina, the retinal pigment epithelium, and the choriocapillaris, which supplies blood to both the outer retina and the retinal pigment epithelium (eFigure 7–43) (eFigure 7–44). In “wet” age-related macular degeneration, choroidal new vessels grow under either the retina or the retinal pigment epithelial cells, leading to accumulation of exudative fluid, hemorrhage, and fibrosis (eFigure 7–45). The onset of visual loss is more rapid and more severe than in atrophic degeneration. The two eyes are frequently affected sequentially over a period of a few years. Although “dry” age-related macular degeneration is much more common, “wet” age-related macular degeneration accounts for about 90% of all cases of legal blindness due to age-related macular degeneration.
Dry (atrophic) age-related macular degeneration with patchy focal atrophy (A) and extensive confluent atrophy (B).
Ultra-widefield (Optomap) images of atrophic age-related macular degeneration. A: Patch of retinal atrophy exposing the underlying choroid (arrow). B: Autofluorescence image highlighting the area of atrophy. (Used, with permission, from S Kiss and Optos plc.)