Age-related macular degeneration (AMD or ARMD) is the most common cause of vision loss in those aged over 50. It causes a gradual loss of central (but not peripheral) vision. Central vision is needed for detailed work and for things like reading and driving. Visual loss can occur within months, or over many years, depending on the type and severity of AMD.
There are two main types of AMD – ‘wet’ and ‘dry’. ‘Wet’ AMD is most severe but more treatable. Visual loss caused by AMD cannot normally be reversed.
Who gets age-related macular degeneration?
AMD is the most common form of macular degeneration and develops in older people. It becomes more common with increasing age, as the name suggests. It is rare under the age of 60. If you develop AMD in one eye, you have a high chance (about 6 in 10) that it will also develop in the other eye.
The two types of age-related macular degeneration
1. Dry AMD
This is the most common form. The RPE of the macula gradually become thin (they ‘atrophy’) and degenerate. It usually takes several years for vision to become seriously affected.
2. Wet AMD
Wet AMD may also be called neo-vascular or exudative AMD. It occurs in about 1 in 10 cases. However, it is likely to cause severe visual loss over quite a short time – sometimes just months. Very occasionally, if there is a bleed (hemorrhage) from a new blood vessel, this visual loss can occur suddenly, within hours or days. In wet AMD, in addition to the retinal pigment cells degenerating, new tiny blood vessels grow from the tiny blood vessels in the choroid. This is called choroidal neo vascularisation. The new vessels break through Bruch’s membrane and into the macular part of the retina. These vessels are not normal. They are fragile and tend to leak blood and fluid.
Certain risk factors increase the risk of developing AMD. These include:
What are the symptoms of age-related macular degeneration?
The main early symptom is blurring of central vision despite using your usual glasses. In the early stages of the condition you may notice that:
One specific early symptom to be aware of is visual distortion. Typically, straight lines appear wavy or crooked. For example, the lines on a piece of graph paper, or the lines between tiles in a bathroom, or the border of any other straight object, etc.
A ‘blind spot’ then develops in the middle of your visual field. This tends to become larger over time as more and more rods and cones degenerate in the macula.
AMD is painless. Symptoms of dry AMD tend to take 5-10 years to become severe. However, severe visual loss due to wet AMD can develop more quickly.
How is age-related macular degeneration diagnosed?
The ophthalmologist will examine the retina to diagnose if it is dry or wet AMD.
Other tests done include ocular coherence tomography (OCT) and Fundus Fluorescein Angiography may be done.
Is there any treatment for age-related macular degeneration?
For the more common dry AMD, there is no specific treatment yet. Low vision rehabilitation and low vision services are offered.. Stopping smoking and protecting the eyes from the sun’s rays by wearing sunglasses are important. A healthy balanced diet rich in antioxidants may be beneficial, as may the addition of dietary supplements (see below for details). Remember that in this type of AMD the visual loss tends to be gradual, over 5-10 years or so.
For the less common wet AMD, treatment may halt or delay the progression of visual loss in some people. Newer treatments may even be able to reverse some of the visual loss. Treatments which may be considered include treatment with anti-vascular endothelial growth factor (anti-VEGF) medicines, photodynamic therapy and laser photocoagulation.