Age-related macular degeneration (AMD) is the term given to ageing changes without any other obvious cause that occurs in the central area of the retina (macula), sometimes with new blood vessel formation (wet AMD). It is the most common form of macular degeneration.
AMD is a painless condition that generally leads to the gradual impairment of vision, but it can sometimes cause a rapid reduction in vision. It predominantly affects the central vision, which is used for reading and recognising faces. Normal macular ageing changes are a common incidental finding on a routine visit to the optometrist, but AMD may also be detected this way before it is symptomatic, or people may present with difficulty in performing daily activities such as driving, reading and recognising faces.
Various ways of classifying AMD have been proposed. This guideline considers the best approach and recommends that a distinction is drawn between 'early' and 'late' disease. Within 'late' disease, distinction should be drawn between disease that is 'wet active' (neovascular lesions that may benefit from treatment), 'wet inactive' (neovascular disease with irreversible structural damage) and 'dry' (non-neovascular disease, including geographic atrophy). An additional category – late AMD (indeterminate) – is introduced to reflect rarer subtypes. For more details, see the age-related macular degeneration classification table.
The consequences of this condition for vision can be severe. AMD is the most common cause of visual impairment in the developed world, and the Royal National Institute of Blind People (RNIB) reports that AMD is the most common cause of certification for vision impairment. In an Australian cohort study of people with early stage AMD, the risk of progression to intermediate or advanced AMD within 5 years was 17%. However, early AMD is not always significantly progressive because 83% did not progress and AMD lesions appeared to have improved and regressed in 8% of people.
The prevalence of late AMD in the UK among people aged 50 years or over is 2.4% (from a meta-analysis applied to UK 2007–09 population data). This increases to 4.8% in people aged 65 years or over, and 12.2% in people aged 80 years or over. The same study found the prevalence of geographic atrophy to be 1.3 to 6.7%, and the prevalence of neovascular AMD to be 1.2 to 6.3%. Estimates indicate that around 39,800 people develop neovascular AMD in the UK each year; given a total UK population of 60 million, this equates to 663 new cases per million per year.
There has been a significant increase in hospital activity in England for episodes with a primary diagnosis of AMD, from less than 10,000 episodes in the years 2005/06 to over 75,000 episodes in the years 2013/14. The most common primary procedure administered in hospital to people with a primary diagnosis of macular degeneration involves intravitreal injection. The cost of aflibercept and ranibizumab, medicines for the treatment of late AMD (wet active), is significant. In 2015/16, ranibizumab was second and aflibercept was fourth in the list of medicines with positive NICE technology appraisals on which the NHS spent most money. Between them, they accounted for a total of around £450 million expended (although some of these costs relate to use for other licensed indications).