Position the grid on the left at your usual comfortable reading distance. Wear the glasses that you use for reading. Cover one of your eyes. Focus on the grid’s centre dot with your other eye. Are you able to see each of the grid’s four corners without shifting your gaze from the centre dot? Do the lines all appear to be straight, continuous and without distortion? (White dots that may appear at the intersections of the lines are a normal optical illusion. Repeat the test with the other eye.
The retina is a thin, clear tissue lining the back of the eye. It is made of sensitive nerve cells that capture light like the film in a camera. The picture the eye sees is sent from the retina through the optic nerve to the brain, which interprets it.
The macula is a very small area in the central retina that is responsible for detailed vision, straight ahead vision and colour vision. It gives the sharp central vision needed to read small print, drive, recognize facial features and do fine needlework. The rest of the retina mainly provides night and peripheral (side) vision. Peripheral vision allows us to see general shapes and movement.
In macular degeneration, the health of the macula breaks down.
Two main types of ARMD exist – a dry and a wet form.
Most cases, approximately 90 per cent, are the dry form of macular degeneration. Here, aging causes the macula to become thin and waste away, which distorts and blurs vision. This type of ARMD comes on gradually and progresses slowly.
The wet type of macular degeneration is less common, but often develops quickly and causes severe visual loss. In this type of macular degeneration, abnormal blood vessels grow under the macula. These blood vessels can leak fluid or a lipid-like material and cause macular edema (swelling). These vessels can also leak blood, causing hemorrhage or a lifting of the macula, called a macular detachment.
Various risk factors can cause age-related macular degeneration. Some risk factors are beyond our control, including:
However, we can control other risk factors. As ARMD is more common in people with a low intake of antioxidant vitamins such as vitamins A, C and E and minerals such as zinc, proper diet and diet supplements may help. Follow the Canada Food Guide recommendations of five to 10 servings of fruits and vegetables daily as a good first step.
A recent study recommended that those over 50 with a mother, father or sibling with macular degeneration should take vitamins designed to delay and reduce the severity of macular degeneration, such as Vitalux Healthy Eyes®.
Antioxidants play a crucial role in reducing the risk of developing age-related macular degeneration. Oxidation is a natural part of the aging process. It continually affects various systems within the body. As part of this process, free radicals (destructive molecules) are created. Free radicals left unbalanced in the eye can damage individual cells, resulting in loss of central vision.
Antioxidants, such as vitamins A, C, E and minerals like zinc, come from the foods we eat and from added supplements. We know that the macula needs a high density of lutein, found in green leafy vegetables. Beta carotene (found in carrots) is similar in the way it works as an antioxidant. Many studies have been done on the proper levels of vitamins and minerals useful in helping with the antioxidation process.
Smoking increases your risk six times compared to someone who doesn’t smoke. If you need one more reason to quit, this is it.
Excessive exposure to sunlight also increases your chances of developing ARMD. A UV 400 block of ultraviolet light helps protect the retina. Wear sunglasses with this protection when you’re outside, even on cloudy days.
A high body mass index and excessive obesity, common in those who are inactive, also increase risk.
To diagnose macular degeneration, an eye exam is done that dilates the pupil. This allows thorough examination of the retina. A fluorescent angiogram may also help with diagnosis and treatment. For this test, dye is injected into a vein in the arm. A camera records a series of photographs as the dye circulates through the retina. Optical coherence tomography (OCT) is also used to determine if the retina is swollen and to evaluate its thickness.
To test your vision at home, use an Amsler grid. Place the grid at a comfortable reading distance and test each eye separately. If you notice a change in the grid pattern such as distortion or absence of the squares, talk to your ophthalmologist or retinal specialist immediately. This generally indicates a change in your macular vision. The more quickly you report it, the more likely any type of treatment is likely to be successful.
With dry macular degeneration, the AREDS (Age-Related Eye Disease Study) showed that vitamin supplements reduce the severe loss of vision in macular degeneration by up to 25 per cent. Vitamins such Vitalux® and Ocuvite® provide the specific combination of vitamins in the right dosage.
For wet macular degeneration, certain proven treatments include photodynamic therapy (PDT) and the use of anti-vascular endothelial growth factor (VEGF) medications.
Photodynamic therapy uses a drug called Visudyne™ which is administered into the arm for 15 minutes. This allows the drug to concentrate in the abnormal leaking blood vessels under the center of vision. It is then activated with cold laser, which changes it in the leaking vessels beneath the macula. The process closes the vessels but does not damage the overlying retina. After treatment, the entire body is light sensitive. You must cover and protect yourself from daylight for two days to prevent severe burning.
More recently, the anti-vascular endothelial growth factor (VEGF) drugs have become available. They block VEGF, which causes the leakage from the abnormal blood vessels beneath the macula. These drugs are injected into the eye. With the addition of these drugs, there is a 95 per cent chance that moderate vision loss can be prevented. There is also a 35 per cent chance that vision can be improved.
If you have moderate to severe macular degeneration, magnifiers and high intensity lamps can help you in the activities of daily living. Fortunately, total loss of vision from macular degeneration is very rare. As a general rule, peripheral vision is not affected. However, it is much better to be proactive. Change your lifestyle, if necessary, to prevent this debilitating loss of vision as you get older. Regular checkups with the ophthalmologist or your retinal specialist are necessary to maintain good healthy retinae.
|Age||Adults over age 50|
|Family History||AMD runs in families (up to three times the risk)|
|Gender||Women are more vulnerable (up to two times the risk)|
|Colouring||Those with light coloured irises and skin may be more susceptible|
|Diet||Low intake of antioxidant vitamins and minerals puts you at higher risk. Canadians 50+ often do not consume Canada Food Guide’s recommendations of 5 to 10 servings of fruits and vegetables daily|
|Smoking||Smokers are more susceptible (up to six times the risk)|
|Extended sunlight exposure associated with 10 year incidence of early AMD|
|Excessive weight /obesity||Excessive weight increases risk, and a high body mass index increases risk of progression|