There are two types of AMD.
Most people (about 75%) have a form called “early” or “dry” AMD, which develops when there is a build-up of waste material under the macula and thinning of the retina at the macula. Most people with this condition have near normal vision or milder sight loss.
A minority of patients with early (dry) AMD can progress to the vision-threatening forms of AMD called late AMD.
The commonest form of late AMD is “exudative” or “wet” AMD. This occurs when abnormal blood vessels grow underneath the retina. These unhealthy vessels leak blood and fluid, which can prevent the retina from working properly.
Eventually the bleeding and scarring can lead to severe permanent loss of central vision, but the eye is not usually at risk of losing all vision (going ‘blind’) as the ability to see in the periphery remains.
There is a rarer form of late AMD called geographic atrophy, where vision is lost through severe thinning or even loss of the macula tissue without any leaking blood vessels.