Macular degeneration (also called age-related macular degeneration or AMD) is the leading cause of blindness and severe vision loss in Australia. The name actually refers to a group of degenerative diseases of the retina – in particular the macula, which is responsible for central and fine-detail vision. Because this is a painless condition and peripheral vision is not affected, many people are not aware that they have AMD until the disease is in the advanced stages. Once advanced, AMD can be classified into wet and dry forms. Most people have the dry form of AMD.
People aged over 50 years or those with a family history of macular degeneration face the greatest risk. This debilitating eye disease causes people to lose the ability to distinguish faces, read, drive and see fine detail. Some people may no longer be able to work. Early detection and treatment offers the best hope of minimising significant damage.
Everyone should have their eyes checked on a regular basis by an optometrist, regardless of whether you require glasses to see. Your optometrist will check your vision and also look for signs of any other eye disease. This is particularly important for conditions such as macular degeneration, where there may not be any noticeable visual abnormalities until late in the disease course. If there are any abnormal signs or you are in a high-risk group (e.g. you smoke, have diabetes or a family history), your optometrist may recommend further tests to examine the retina and can refer you to a retinal specialist.
If you have difficulty reading, distinguishing faces, or start to see dark or empty patches in your central vision, have your eyes checked immediately.
You can perform some simple screening tests for macular degeneration at home. For those over the age of 50, look at a straight edge (e.g. of a door or window) one eye at a time to see if there are any ‘bumps’ or missing parts to the line. If there are, have your eyes checked immediately.
An Amsler Grid may be recommended for people at high risk of developing macular degeneration. Named after Swiss ophthalmologist Marc Amsler, this grid contains a series of horizontal and vertical lines with a dot in the middle. If the lines appear wavy or any are missing, have your eyes checked immediately.
This test (sometimes called retinal photography or eye angiography) uses a fluorescent dye to show any blockages or leaks in the blood vessels supplying the retina. The dye is usually injected into a vein in your arm and flows through the blood system to the retinal blood vessels. Your ophthalmologist will use a special camera to take photographs. Please note that your vision will be blurred for up to 12 hours after the test, as your pupil will be dilated using eye drops.
Optical coherence tomography (OCT) is a non-invasive test that captures detailed images of the retina. The scan allows the ophthalmologist to identify areas of retinal thinning, thickening, or swelling caused by fluid build-up and leaky blood vessels. Your pupils will be dilated for this test and the procedure takes less than 10 minutes. The scans are performed without the need for direct contact with your eyes.
There is no cure for wet macular degeneration, although some treatments can slow or stop progression of the disease and vision can be maintained (or even improved) for many people.
The benefits of early treatment are:
For wet macular degeneration, early detection is vital because eye (intravitreal) injections can be used to stop abnormal blood vessels leaking and dry up the abnormal macular fluid (oedema). Repeated injections and regular monitoring can prevent further vision loss in 95% of sufferers. Vision is significantly improved in up to 40% of those treated.
Vascular Endothelial Growth Factor (VEGF) is a protein secreted by oxygen-deprived cells. Low levels of VEGF are normal; however when there are high levels of this protein, abnormal blood vessels will grow. Anti-VEGF drugs (e.g. Lucentis, Avastin and Macugen) block the protein and the corresponding abnormal blood vessel growth – they are given as eye injections. These drugs are used in the treatment of macular degeneration and diabetic retinopathy.
Anaesthetic drops are used to numb the eye, and the injection is given via a tiny needle from the side – you won’t be able to see the needle coming towards your eye. You may feel slight pressure, but there won’t be any pain.
Photodynamic therapy is used for a small number of patients who have a specific type of AMD. A special dye, known as a photosensitiser, is injected into an arm vein and flows through the blood system to the retinal blood vessels at the back of the eye. A cold laser is then used to activate the dye, with the resultant photochemical effect shrinking and sealing abnormal blood vessels. Many people will need to be treated about every 3–4 months.
Eye injections may be used in conjunction with photodynamic therapy.
Unfortunately, there is no approved treatment for patients with the dry form.
Research studies investigating disease progression and potential therapies, some of which involve Vision Eye Institute specialists, are currently ongoing.
Smokers are three times more likely to develop macular degeneration (in addition to a number of other serious health-related issues), so now is the time to quit.
Research has shown eating foods rich in carotenoids are particularly beneficial. These include dark green leafy vegetables (e.g. spinach and kale) and coloured vegetables (particularly gold-coloured ones, e.g. corn, yellow capsicum, sweet potato). Foods rich in vitamin C, omega-3 fatty acids (e.g. oily fish such as salmon) and zinc are also good for eye health.
Dr Simon Chen was featured on Optometry Australia's Ten Minute Tutes podcast to discuss age-related macular degeneration (AMD) and guidelines for when optometrists should refer patients with AMD to an ophthalmologist.