Age-related macular degeneration is caused by a combination of ageing-related biological changes, inherited susceptibility and environmental or systemic risk factors rather than by one isolated cause. The macula is particularly metabolically active because it contains densely packed photoreceptors that require substantial energy and constant maintenance. Over time, cumulative cellular stress can impair the retinal pigment epithelium, photoreceptors and supporting structures.
Abnormal deposits known as drusen can accumulate beneath the retina, while inflammatory, oxidative, metabolic and complement-mediated processes may contribute to progressive tissue damage. In wet AMD, additional pathological signalling promotes abnormal blood-vessel growth and leakage. Consequently, the term “cause” encompasses a network of interacting mechanisms rather than a single infectious or traumatic event.
Age is the strongest broad risk factor because AMD becomes substantially more common as people get older. Ageing affects retinal cellular maintenance, waste processing, vascular regulation and the balance of inflammatory and repair pathways. The macula must continuously recycle components of photoreceptor outer segments and manage metabolic by-products, so age-related decline in these systems can increase susceptibility to dysfunction. Age alone does not guarantee AMD, however, and many older people never develop advanced disease. The distinction between age being a major risk factor and age being a sufficient cause is important. AMD emerges from the interaction of ageing with genetic predisposition and other exposures, meaning that two people of the same age can have very different retinal health.
Genetics plays an important role. Having a family history of AMD increases risk, and research has identified numerous genetic variants associated with susceptibility, including variants affecting complement regulation, lipid metabolism and other retinal processes. Some genetic changes increase the likelihood of developing disease without determining that disease will definitely occur. This is characteristic of a complex multifactorial condition rather than a simple single-gene disorder. Genetic predisposition may also influence disease subtype, progression and response to certain biological pathways. Because the interaction between genes and environment is complex, genetic risk should not be interpreted as a deterministic diagnosis, and routine clinical examination remains central to identifying actual retinal changes.
Smoking is one of the clearest modifiable risk factors for AMD. Tobacco smoke exposes the body to oxidative and inflammatory stress and can affect vascular function and retinal cellular health. Epidemiological studies consistently associate smoking with increased AMD risk, and stopping smoking is therefore an important component of reducing risk or slowing progression.
Other cardiovascular and metabolic factors also matter: maintaining healthy blood pressure and cholesterol levels and engaging in regular physical activity are associated with better overall vascular health and are recommended as part of AMD risk reduction. These measures do not guarantee prevention because genetic and age-related factors remain important, but they can modify risk. The National Eye Institute specifically recommends avoiding smoking, maintaining healthy blood pressure and cholesterol, exercising and eating a healthy diet.
Diet and nutritional status are linked to retinal health because the retina has substantial metabolic requirements and depends on nutrients involved in antioxidant and cellular processes. Observational research has associated dietary patterns rich in leafy green vegetables and fish with healthier ageing of the macula. Nutritional supplements have a more specific role in established intermediate or certain advanced AMD based on clinical trial evidence rather than as a general preventive treatment for everyone.
AREDS-type formulations contain selected antioxidant vitamins and minerals, with later formulations modifying ingredients such as zinc, copper, lutein and zeaxanthin according to evidence. They do not restore retinal cells that have already been lost and are not appropriate substitutes for professional assessment. Nutrition is therefore one component of risk management rather than a cure for AMD.
The mechanisms underlying dry and wet AMD differ in their immediate pathological expression. Dry AMD involves degeneration and loss of retinal cells and supporting tissue, including geographic atrophy in advanced disease. Wet AMD involves pathological angiogenesis, meaning abnormal blood-vessel growth, followed by leakage and haemorrhage that damage the macula. A major molecular driver of this process is vascular endothelial growth factor, or VEGF, which is why anti-VEGF treatment is effective in many cases of wet AMD. Importantly, wet AMD can arise from an eye that previously had dry AMD, so these forms should not be viewed as entirely unrelated. Understanding the distinction explains why anti-VEGF injections are not simply a general treatment for every form of macular degeneration.
Several conditions and exposures may influence risk, but not every reported association has the same level of evidence. Cardiovascular risk factors, obesity, hypertension and abnormal lipid metabolism have been investigated because retinal health is closely related to vascular and metabolic biology. High myopia and other ocular characteristics can also influence the differential diagnosis of central retinal changes, although they should not automatically be equated with AMD.
Importantly, AMD is not caused by reading, television, ordinary computer use, eye strain or normal use of the eyes. It is also not an infection and cannot be caught from another person. The term “degeneration” reflects progressive tissue dysfunction and loss rather than a contagious process.
Because AMD is multifactorial, prevention focuses on reducing modifiable risk rather than guaranteeing avoidance. Not smoking is particularly important, while regular physical activity, management of blood pressure and cholesterol, and a balanced diet containing vegetables and fish may contribute to healthier ageing. Regular eye examinations are important because early AMD can be asymptomatic and because timely recognition of conversion to wet AMD can allow treatment before substantial additional central vision is lost.
Sudden new distortion, a rapidly developing central blur or other abrupt visual changes warrant prompt eye assessment because they can indicate active wet AMD or another retinal emergency. The current understanding therefore combines age-related retinal biology, genetics, vascular and metabolic influences, oxidative and inflammatory mechanisms and abnormal angiogenesis rather than attributing AMD to a single cause.
