In fact, although only 10 percent of patients develop new blood vessels, this complication is responsible for most of the legal blindness associated with macular degeneration. By far the most successful to date has been the use of laser light to cauterize the blood vessels. Causes of Macular Degeneration Physicians have wondered about the causes of macular degeneration for over a century. In the late 1800s, when doctors first began looking into eyes with ophthalmoscopes, they believed that the drusen they observed represented some type of infection, or at least inflammation, of the choroid. Even today, there is some evidence to suggest that the body's immune system plays a role in the development of some forms of macular degeneration, especially the development of neovascularization.
Environmental factors make up another group of possible causes.
Epidemiologists have searched for evidence of such factors for decades. Another important group of possible causes of age-related macular degeneration is mildly abnormal genes. It has been recognized for over a century that some forms of macular degeneration run in families. During the past 25 years, increasing evidence has been gathered to suggest that a significant fraction of macular degeneration has a hereditary basis. This has important implications for understanding macular degeneration at the molecular level, as well as for designing improved treatments for the disease.