Age-related macular degeneration (AMD) is a chronic and progressive degenerative disease of the macula, the central part of the retina, which culminates in blindness and affects mainly the elderly population. AMD pathogenesis and pathophysiology are complex due to the structural and cellular complexity of the retina and subretinal tissues, and the variety of risk factors and molecular mechanisms that contribute to disease onset and progression.
AMD develops with age and there are 2 types, termed dry and wet. Dry AMD has 3 stages: early, intermediate, and late. It usually progresses slowly over several years. There is no treatment for late dry AMD, often called Geographic Atrophy.
Wet AMD (also called neovascular AMD) is other late-stage form of AMD and this usually causes more rapid visual loss. Wet AMD can develop at any stage of dry AMD and is the result of pathological blood vessels growing in the macula. Effective treatment options are available for wet AMD.
AMD is driven by a combination of genetic predisposition, natural ageing changes and lifestyle factors, such as smoking or nutritional intake. The mechanism by which these risk factors interact and converge towards AMD are not fully understood and therefore drug discovery is challenging particularly in the management of dry AMD, where no therapeutic attempt has been successful thus far.
Genetic and molecular studies have identified the complement system as a key driver of AMD onset and progression, and there is increasing evidence that complement inhibition can slow the progression of geographic atrophy.