Macular degeneration
What is age-related macular degeneration?
The back of the eye consists of a highly specialised neural tissue called the retina. This is responsible for turning what we see in our environment into electrical impulses that are transmitted to our brains.
The centre of the retina is the macula. The macular is responsible for fine visual tasks such as reading, writing, driving and face recognition.
Age-related macular degeneration (AMD) is a degenerative condition that usually affects people over the age of 60 and can cause a reduction in central vision. It is one of the leading causes of vision loss in our community.
There are two types of AMD but both may occur in the same eye. These are known as Wet AMD and Dry AMD.
Dry AMD has many stages. The earliest is when waste products that are normally cleared by the retina begin to accumulate. These are called drusen. Other dry changes include retinal pigment epithelial changes and Geographic Atrophy (GA).
GA represents end-stage AMD and can cause significant visual loss. There are new treatments known as complement inhibitors for this subtype of the disease. These are designed to slow the progression of GA.
Wet AMD occurs when abnormal blood vessels grow beneath the retina. These vessels leak blood and fluid into the retina causing reduced vision. In the last two decades treatment for wet AMD has been revolutionised by a type of medication known as Anti-VEGF (Anti-vascular endothelial growth factor) injections.
Preventing progression of AMD
- Do not smoke – studies have shown that AMD is more severe and progresses more rapidly in smokers.
- Eat deep sea fish rich in omega 3 regularly (up to 3 times per week).
- Have a diet that is rich in green leafy vegetables that contain Lutein (such as spinach, curly kale and broccoli). Other healthy fruit and vegetables include ones with Vitamin C and Zeaxanthin such as corn, papaya and capsicum.
- Anti-oxidants such as those found in blueberries, red kidney beans and green tea are thought to be beneficial.
- Limit saturated fats.
- There is some evidence that taking a dietary supplement slows progression of disease in some patients.
How is AMD diagnosed?
You may be told you have signs of early AMD at a routine Optometry review. Often at this stage you will not have noticed a change in your vision and you can be monitored regularly without treatment.
Alternatively, you may experience central distortion or loss of vision. Your Optometrist or Ophthalmologist will then perform a detailed examination to diagnose the problem. This includes measuring your vision and dilating your pupils to examine the retina.
It is often necessary to perform extra tests to diagnose AMD. These include:
How is AMD treated?
Wet AMD is routinely treated with injections into the eye of anti-VEGF (vascular endothelial growth factor) medications. These are anti-bodies that block VEGF and therefore temporarily slow the growth of the blood vessels. There are several anti-VEGF agents that are TGA approved in Australia for use in AMD. Dr Cohn will discuss the most appropriate treatment for you.
The drugs are all intravitreal injections that are safely injected into the back of the eye in the doctor’s rooms. Millions of injections have been performed world-wide to date with excellent results.
Studies have shown that the majority of patients with regular injections maintain their vision (that is the vision they presented to the doctor with) and up to one third of patients improve vision. A small percentage of patients continue to lose vision despite treatment. This may be due to ongoing dry AMD which cannot be treated currently. The goal of anti-VEGF treatment is to prevent further visual loss.
The drugs have a duration of action of between 4 and 16 weeks and therefore treatment needs to be repeated. Almost all patients require ongoing treatment indefinitely to prevent further visual loss.