Macular degeneration (MD) occurs when the macula at the back of the eye is damaged. The macula is the part of the retina that gives you sharp and detailed vision. We use the macula for reading, driving, recognising faces, watching television, and for doing fine detail work.
MD usually affects both eyes, but it may produce symptoms in one eye first. If MD continues to late stages, severe and permanent visual loss or blindness can result. In most cases, visual loss occurs gradually and affects the central part of your vision meaning that you can still see to the sides from each eye. The most common type of MD is age-related macular degeneration (AMD).
AMD is primarily age related—the older you are, the greater your risk. It is also important to know if there is MD in your family. A family history of the disease significantly increases your chances of having AMD. People who smoke and those with a diet low in certain important nutrients are also at higher risk.
Early AMD – this is where waste products build up under the macula producing deposits called drusen. This stage does not normally cause any vision problems, but changes to diet and lifestyle (see later) can help to slow the progression of the disease. About 85% of people with AMD have early stage disease.
Late AMD – this is where the disease has progressed and vision is affected. There are two main forms of late AMD:
1. Dry AMD – develops slowly, usually over many years. As cells in the macula die in small patches, images fade and become unfocused, and small pieces of image go missing. Eventually, only side vision will remain. About a third of late AMD cases are the dry form.
2. Wet AMD – new, abnormal blood vessels grow from the choroid layer (at back of the eye) under or into the macula. These vessels leak and bleed. Scar tissue forms in and around the macula. Wet AMD can cause sudden changes in vision – even overnight. Changes include distortion and/or a blank or blurry patch in the central area of vision. About 2/3 of late stage AMD is the wet form, although both dry and wet types often co-exist.
If you are over age of 50, it is a good idea to schedule an eye examination with an optometrist or ophthalmologist every one to two years to look for the earliest signs of AMD before any vision loss has occurred.
In most cases, the earlier that AMD is detected the more likely you are to hold onto your vision. You can also monitor for symptoms of AMD, on a daily basis using an Amsler grid, one eye at a time, using normal reading glasses, if worn. If you find symptoms, or notice any sudden changes in vision or distortion, request an urgent review by an ophthalmologist. Looking for symptoms with an Amsler grid should not replace regular eye checks by a health professional as you can still have AMD and not see any changes on the Amsler grid.
Click here for a downloadable Amsler grid and comprehensive information about Macular Degeneration from the Macular Disease Foundation Australia
If you are diagnosed with AMD it is important to work with your ophthalmologist in understanding the disease and developing a treatment plan. Your ophthalmologist has the qualifications and experience to treat all medical and surgical aspects of AMD.
She/he may also direct you to a support group for further information and suggest access to rehabilitation options, including a variety of tools and resources that can make everyday living with AMD significantly easier.
Significant advances have been made in the treatment of wet AMD. The aim of treatment is to prevent the condition from getting worse as there is no cure for AMD. The earlier the disease is detected, the more vision you are likely to retain. Treatments include:
1. Anti-VEGF (vascular endothelial growth factor) drugs – to reduce leakage and bleeding from new blood vessels in the macula
2. Photodynamic therapy – uses a light-sensitive chemical and some gentle laser to destroy abnormal blood vessels
3. Laser photocoagulation – uses a laser beam close off abnormal blood vessels.
Treatment of wet AMD is safe but does have risks of complications. Talk with your ophthalmologist about possible risks.
Treatment options, especially for early and dry AMD, include changing your diet, not smoking and in some instances taking vitamin supplements.
The Age-related Eye Disease Studies (AREDS) show there is good, long term evidence that certain vitamin supplements can reduce the risk of progression of AMD. However, the evidence exists only for those patients who have certain features in the macula that increase their risk of progression.
For more information, visit the Macular Disease Foundation Australia: http://www.mdfoundation.com.au
