Age-related macular degeneration (AMD) is caused by the deterioration of the macula, the central part of the retina responsible for sharp central vision, due to a combination of advancing age, genetic predisposition, and lifestyle factors including smoking and diet. It is the leading cause of irreversible vision loss in Australians over 50. Understanding what causes macular degeneration, who is at risk, and how it is detected and treated is an important step in protecting your long-term eye health.
What Is the Macula?
The macula is the specialised central area of the retina, approximately five millimetres in diameter, containing a very high concentration of cone photoreceptors responsible for sharp, colour, and fine-detail vision. It is the part of the retina used for reading, recognising faces, watching television, and driving. When the macula is damaged, central vision becomes blurred or distorted, while peripheral vision is generally preserved.
The retina is the light-sensitive layer at the back of the eye. The macula is a specialised area at the centre of the retina, approximately five millimetres in diameter, containing a very high concentration of cone photoreceptors, the cells responsible for sharp, colour, and fine-detail vision. The macula is what we use to read, recognise faces, watch television, and drive. When the macula is damaged, central vision becomes blurred or distorted, while peripheral (side) vision is generally preserved.
Dry AMD and Wet AMD
AMD presents in two main forms. Dry AMD, which accounts for approximately 85 to 90 percent of cases, involves a gradual accumulation of protein deposits (drusen) beneath the retina and slow macular cell deterioration over years. Wet AMD, while less common, is responsible for most severe vision loss from AMD and occurs when abnormal blood vessels grow beneath the macula and leak fluid and blood, causing rapid central vision loss that requires prompt treatment.
AMD presents in two main forms. Dry AMD is the more common form, accounting for approximately 85 to 90 per cent of cases. It involves a slow, gradual deterioration of the macular cells, often with the accumulation of small protein deposits beneath the retina called drusen. Dry AMD typically progresses over years and may cause no symptoms in its early stages. In some patients it advances to geographic atrophy, a more severe form with significant areas of macular cell loss.
Wet AMD, or neovascular AMD, accounts for a smaller proportion of cases but causes the majority of severe vision loss. It occurs when abnormal new blood vessels grow beneath the macula, leaking fluid and blood into the retinal layers. This causes rapid and potentially severe distortion and loss of central vision. Wet AMD is a medical urgency, and early treatment gives the best chance of preserving vision.
Causes and Risk Factors
AMD is caused by a combination of advancing age, genetic predisposition, and modifiable lifestyle factors. Age is the most significant risk factor. AMD is rare under 50 and becomes progressively more common with each decade. Smoking doubles to triples the risk of AMD and is the most important modifiable risk factor. Family history in a first-degree relative substantially increases risk. Cardiovascular disease, obesity, low dietary antioxidant intake, and prolonged UV exposure without eye protection also contribute.
Age is the most significant risk factor. AMD is rare under 50 and becomes progressively more common with each decade thereafter. Family history is a powerful independent risk factor: if a first-degree relative has had AMD, your own risk is substantially higher, and earlier and more frequent eye checks are strongly recommended.
Smoking is the most important modifiable risk factor. Smokers have double to triple the risk of developing AMD compared to non-smokers, and the risk begins to fall meaningfully after stopping smoking. Cardiovascular disease and high blood pressure are also associated with increased AMD risk, reflecting the important role of vascular health in retinal function.
Diet plays a contributing role. A low intake of antioxidants, lutein, and zeaxanthin, found in green leafy vegetables such as kale, spinach, and silverbeet, is associated with higher AMD risk. Prolonged exposure to ultraviolet light without adequate eye protection may also be a factor. People of European descent have a higher susceptibility to AMD than those of East Asian or African heritage.
What AMD Does Not Cause
AMD does not cause total blindness. The peripheral retina is not affected, and patients retain side vision even when central vision is severely reduced. With low-vision supports and assistive technology, many people with advanced AMD can continue to function with meaningful independence. However, loss of central vision significantly affects the ability to read, drive, and recognise faces, which is why early detection and treatment are so important.
It is important to understand that AMD does not cause total blindness. The peripheral retina is not affected by the condition, and patients retain their side vision even when central vision is severely reduced. With the aid of low-vision supports and assistive technology, many people with advanced AMD can continue to function independently. However, the loss of central vision is profoundly disabling, affecting the ability to read, drive, and recognise faces, which is why early detection and treatment are so important.
Detection, Treatment, and When to Seek Urgent Review
Because early AMD often causes no symptoms, regular eye examinations are essential for everyone over 50, and earlier for those with a family history. For wet AMD, intravitreal anti-VEGF injections (Eylea, Lucentis, Vabysmo) are the standard of care, suppressing abnormal vessel growth and reducing fluid. For dry AMD, the AREDS2 antioxidant supplement formula has been shown to slow progression in intermediate and advanced disease. Lifestyle changes, including quitting smoking, managing blood pressure, and eating a diet rich in leafy greens, are also recommended.
Because early AMD often causes no symptoms, regular eye examinations are essential for everyone over 50, and earlier for those with a family history. Home monitoring with an Amsler grid (a simple grid of vertical and horizontal lines with a central dot) can help detect early changes between appointments. If straight lines appear wavy or distorted, or if a blank spot appears, you should seek urgent review from your ophthalmologist.
For wet AMD, the mainstay of treatment is intravitreal anti-VEGF injection therapy. Medications such as Eylea, Lucentis, and Vabysmo are injected into the vitreous cavity of the eye under topical anaesthesia, suppressing abnormal vessel growth and reducing fluid accumulation. When treatment is started promptly, the majority of patients experience stabilisation of vision and many experience meaningful improvement. For dry AMD, there is currently no specific medical treatment to reverse the condition, but the AREDS2 antioxidant supplement formula has been shown in large clinical trials to slow progression in intermediate and advanced disease. Lifestyle measures, including quitting smoking, managing blood pressure, and eating a diet rich in leafy greens and oily fish, are also recommended for all patients with AMD.