What is Age Related Macular Degeneration?
Age Related Macular Degeneration (AMD) occurs due to degenerative changes in the macula, the most sensitive central portion of the retina at the back of the eye. This reduces central vision and affects activities such as reading, recognising faces, watching television and driving.
What causes AMD?
The causes aren’t fully known. The major cause is advancing age. A lifetime of exposure to light, oxidisation and reduced blood flow can result in abnormal macular changes. There are two types of AMD.
The “dry” type occurs where the macular tissue accumulates deposits called drusen. This is associated with loss of pigment in the retinal pigment epithelium. It is a gradual process and affects about 90 per cent of people who have AMD.
“Wet” or exudative AMD occurs less commonly when fluids leak from newly formed blood vessels beneath the macula. This can be associated with rapid central vision loss. Only 10 per cent of people with AMD have the wet form.
How common is AMD?
AMD affects mainly older people and affects more women than men. In Australia, 9 per cent of those over 50 years, 23 per cent of those over 65 years and 31 per cent of those aged over 80 years have some form of AMD.
What are the risk factors for AMD?
The most significant preventable risk factor for AMD is smoking. Smokers are about 2.5 times more likely to develop AMD than those who have never smoked. Screening for signs of AMD are indicated for those who:
- are over 50 years of age;
- have hypertension or cardiovascular disease;
- have a family history of AMD;
- have a strong history of UV light exposure eg. outdoor work;
How is AMD detected and diagnosed?
People who have AMD may not realise that they have a problem until their central vision becomes distorted or blurred. A retinal examination by an optometrist or ophthalmologist can detect early AMD. The eye care practitioner may use eye drops to dilate the pupils to permit a better view of the retina at the back of the eye.
Another test that may be used is the Amsler Grid (see illustration). People having AMD often report that sections of the regular grid pattern may appear distorted or missing. Changes to the grid pattern may indicate progression of AMD, so it’s important to report any changes in appearance to the Amsler Grid pattern to your eye care practitioner.
Optometrists will refer people whom they suspect have AMD to an ophthalmologist (eye specialist) for confirmation of the diagnosis and further investigation. The ophthalmologist may perform a test called Fluorescein Angiography where a dye is injected to enable the ophthalmologist to observe progress of the dye through the retinal blood vessels. This reveals any leaking blood vessels.
Other tests used to diagnose AMD include retinal photography, visual field testing and macular function tests such as colour vision tests and contrast sensitivity tests.
Can AMD be treated?
AMD can be treated but not cured.
Most body tissues that are damaged can regrow and repair the damage. The retina is nerve tissue and this cannot regenerate. Crucial to treatment is early detection of change.
At present there is no treatment for dry AMD. Preventive measures including stopping smoking, a well balanced diet high in dark green leafy vegetables and fruit, and dietary supplements containing zinc and anti-oxidant vitamins E, C and beta carotene have been demonstrated to be beneficial in slowing progression of some forms of AMD. Use of supplements should be determined in consultation with health care practitioners.
Currently there are three available surgical treatments for wet AMD:
Laser photocoagulation is the application of a laser to seal leaking blood vessels and retard the growth of abnormal blood vessels. Vision usually does not improve after laser treatment, and may even be worse. However, the loss of vision after this treatment is usually less severe than the eventual loss of vision if no laser treatment is performed.
Photodynamic therapy (PDT) uses a non thermal laser in conjunction with a light sensitive drug called Visudyne. This also seals leaking vessels and halts or slows the growth of abnormal blood vessels without the resultant blind spots associated with laser photocoagulation. This treatment suits only a small proportion of those people who have wet AMD and multiple treatments may be required.
Anti VEGF (vascular endothelial growth factor) is a treatment that is injected directly into the eye. As with the above therapies, these drugs seal leaking vessels and prevent or slow the growth of abnormal blood vessels. Multiple treatments may be required to achieve optimal results. Anti VEGF drugs currently used include Lucentis (R), Avastin (R) and Eylea (R)
All these treatments are performed by an ophthalmologist. You can find out more about AMD treatments at the Macular Degeneration Foundation here
Vision Aids for AMD
Many people with AMD experience reduced vision. Those with low vision because of AMD may have problems reading and seeing detail even with spectacles. Assistance in the form of low vision aids is available from optometrists and organisations such as Vision Australia. Magnifiers, large print books, closed circuit televisions and improved lighting may help significantly.
What should you do about AMD?
- (If you do) stop smoking
- Schedule regular eye examinations with your eye care practitioner
- Eat a healthy diet containing leafy green vegetables and reduced intake of processed foods high in concentrated vegetable oils.
- Reduce exposure to sunlight and wear sunglasses outdoors
Early detection of the retinal changes of AMD is important for effective management and treatment.
Have your eyes examined immediately you notice a change in the quality of your vision.
Can I claim treatment for AMD from HCF?
Consultations for detection and treatment of AMD may be claimed through Medicare. Check consultation fees and benefits with your eye care practitioner.
Visit, call or make an appointment on-line with one of our centres if you are concerned about the health of your eyes or would like to book an appointment for an eye examination.