Age-related macular degeneration.

Age-related macular degeneration is a common cause of blindness. Its incidence is increasing, partly due to the advancing age of the population in North America and Europe, but there is no doubt that the age-adjusted rates are also increasing, which points to some environmental influence. The condition is characterized by the appearance of retinal deposits called drusen. These and other changes form a barrier between the retinal pigment epithelium and the choroidal circulation. As a result, new vessels may grow from the choroid and penetrate the retina. These new vessels are delicate and can leak or bleed. Such episodes occur in the "wet" form of age-related macular degeneration and cause the well known disciform degeneration, which in turn leads to distortion of the image and rapid loss of vision. Even when this does not happen, areas of retina may atrophy, probably due to anoxia: this is the "dry" form of the disease, also called geographic atrophy. In trials, scattered laser burns have been applied to the retina but the long-term benefits of this are as yet uncertain. New micro-pulse lasers are coming into use which may be more effective. Surgical treatments include translocation of the retina and photodynamic therapy. Medical therapies attracting attention are intraocular injections of anti-angiogenic drugs, such as ranibizumab. These need further evaluation, as does the role of diet. Within a few years blindness due to age-related macular degeneration may be reduced by combining dietary control, screening for visual loss, and medical and surgical methods of treatment.