The pathogenesis of AMD is only partly understood, and its etiology remains obscure. The Retinal and Choroidal Diseases Panel of the National Advisory Eye Council has stated that "none of the fundamental causes of any type of macular disease is known, and none can be prevented." Thus, this panel recommended that one of the NEI's program development priorities should be to "initiate epidemiologic studies of macular diseases to identify possible causative, protective, or aggravating factors."