Age-related macular degeneration (AMD) is a deterioration or breakdown of the eye's macula. The macula is a small area in the retina — the light-sensitive tissue lining the back of the eye. The macula is the part of the retina that is responsible for your central vision, allowing you to see fine details clearly.
In its earliest stages, people may not be aware they have macular degeneration until they notice slight changes in their vision or until it is detected during an eye exam. People who are at risk for macular degeneration should have regular eye exams to test for macular degeneration and, if diagnosed, begin treatment if appropriate.
Dry macular degeneration signs and symptoms
- Blurry distance and/or reading vision
- Need for increasingly bright light to see up close
- Colours appear less vivid or bright
- Hazy vision
- Difficulty seeing when going from bright light to low light (such as entering a dimly lit room from the bright outdoors)
- Trouble or inability to recognize people's faces
- Blank or blurry spot in your central vision
Dry macular degeneration can affect one or both eyes. You may not notice vision changes if only one eye is affected, as your unaffected eye will compensate for vision loss in the other eye.
Wet macular degeneration symptoms usually appear and get worse fairly quickly. Wet macular degeneration signs and symptoms:
- Distorted vision — straight lines will appear bent, crooked or irregular
- Dark grey spots or blank spots in your vision
- Loss of central vision
- Size of objects may appear different for each eye
- Colours lose their brightness; colours do not look the same for each eye
Recently much new information on macular degeneration has been discovered. Genetic changes appear to be responsible for approximately half the reason for individuals getting macular degeneration. Additionally, there are other risk factors for developing the disease. Many older people develop macular degeneration as part of the body's natural aging process. One large study found that the risk of getting macular degeneration jumps from about 2 percent of middle-aged people in their 50s to nearly 30 percent in people over age 75.
Oxidative stress and macular degeneration
Our bodies constantly react with the oxygen in our environment. Over our lifetimes, as a result of this activity, our bodies produce tiny molecules called free radicals. These free radicals affect our cells, sometimes damaging them. This is called oxidative stress and is thought to play a major role in how macular degeneration develops. Approximately 1 in 3 Caucasians have genetic changes that make them more prone to damage from oxidative stress, which can lead to macular degeneration.
Macular degeneration in families
Heredity is another risk factor for macular degeneration. People who have a close family member with the disease have a greater chance of developing macular degeneration themselves.
Inflammation and macular degeneration
Some studies have shown that inflammation (swelling of the body’s tissues) may play a role in macular degeneration development. Inflammation is the way the body’s immune system fights off infection or other things it considers “invaders.” But an overactive immune system with its associated inflammation may be a risk factor for macular degeneration.
Smoking, high blood pressure and abnormal cholesterol and macular degeneration
Smoking and high blood pressure are associated with the wet form of macular degeneration. Research also suggests there may be a link between being obese and having early or intermediate-stage macular degeneration develop into the advanced (wet) form.
Another risk factor for developing macular degeneration may include having abnormal cholesterol levels or having high blood pressure (called hypertension).
Many people do not realize they have a macular problem until they notice they have blurred or distorted vision. Regular eye exams by an ophthalmologist may help to detect problems or early stages of macular degeneration before you are even aware of them.
Dry macular degeneration: detection with an ophthalmoscope
To check for macular degeneration, your eye doctor will dilate (widen) your pupils using eyedrops and examine your eyes with an ophthalmoscope, a device that allows him or her to see the retina and other areas at the back of the eye. If macular degeneration is detected, your doctor may have you use an Amsler grid to check for macular degeneration symptoms such as wavy, blurry or dark areas in your vision.
Wet macular degeneration: detection with fluorescein angiography and optical coherence tomography
If your ophthalmologist suspects you may have the wet form of macular degeneration, he or she will take special photographs of your eye with fluorescein angiography and optical coherence tomography (OCT). OCT scanning is a sophisticated and exact tool that detects abnormal blood vessels by creating a special picture of your macula.
During fluorescein angiography, a fluorescein dye is injected into a vein in your arm. The dye travels throughout the body, including your eyes. Photographs are taken of your eye as the dye passes through the retinal blood vessels. Abnormal areas will be highlighted by the dye, showing your doctor whether wet macular degeneration treatment is possible and, if so, where to treat the abnormal vessels.
Dry AMD and nutritional supplements
Unfortunately, at this time there is no single proven treatment for the dry form of macular degeneration. However, a large scientific study has shown that antioxidant vitamins and zinc may reduce the impact of macular degeneration in some people by slowing its progression toward more advanced stages.
The Age-Related Eye Disease Study 2 (AREDS2) showed that among people at high risk for developing late-stage, or wet, macular degeneration (such as those who have large amounts of drusen or who have significant vision loss in at least one eye), taking a dietary supplement of vitamin C, vitamin E, lutein and zeaxanthin, along with zinc, lowered the risk of macular degeneration progressing to advanced stages by at least 25 percent. The supplements did not appear to provide a benefit for people with minimal macular degeneration or people without evidence of the disease during the course of the study.
Following is the nutrient supplementation shown to be beneficial in lowering the risk of macular degeneration progressing to advanced stages:
- Vitamin C – 500 mg
- Vitamin E – 400 IU
- Lutein – 10 mg
- Zeaxanthin – 2 mg
- Zinc oxide – 80 mg
- Copper (as cupric oxide) – 2 mg (to prevent copper deficiency, which may be associated with taking high amounts of zinc)
Another large study in women showed a benefit from taking folic acid and vitamins B6 and B12. Other studies have shown that eating dark leafy greens, and yellow, orange and other colorful fruits and vegetables, rich in lutein and zeaxanthin, may reduce your risk for developing macular degeneration.
These vitamins and minerals are recommended in specific daily amounts in addition to a healthy, balanced diet. Some people may not wish to take large doses of antioxidants or zinc because of medical reasons.
It is very important to remember that vitamin supplements are not a cure for macular degeneration, nor will they give you back vision that you may have already lost from the disease. However, specific amounts of these supplements do play a key role in helping some people at high risk for developing advanced (wet) AMD to maintain their vision, or slow down the progression of the disease.
Talk with your ophthalmologist to find out if you are at risk for developing advanced macular degeneration, and to learn if supplements are recommended for you.
Wet macular degeneration treatment
Treating the wet form of macular degeneration may involve the use of anti-VEGF treatment, thermal laser treatment or photodynamic therapy (PDT). Treatment of wet macular degeneration generally reduces—but does not eliminate-- the risk of severe vision loss.
Anti-VEGF medication injection treatments for wet macular degeneration
A common way to treat wet macular degeneration targets a specific chemical in your body that causes abnormal blood vessels to grow under the retina. That chemical is called vascular endothelial growth factor, or VEGF. Several new drug treatments (called anti-VEGF drugs) have been developed for wet AMD that can block the trouble-causing VEGF. Blocking VEGF reduces the growth of abnormal blood vessels, slows their leakage, helps to slow vision loss, and in some cases improves vision.
Your ophthalmologist administers the anti-VEGF drug (such as Avastin, Lucentis, and Eylea) directly to your eye in an outpatient procedure. Before the procedure, your ophthalmologist will clean your eye to prevent infection and will use an anesthetic drop or injection of anesthetic with a very fine needle to numb your eye. You may receive multiple anti-VEGF injections over the course of many months. Repeat anti-VEGF treatments are often needed for continued benefit.
In some cases, your ophthalmologist may recommend combining anti-VEGF treatment with other therapies. The treatment that’s right for you will depend on the specific condition of your macular degeneration.
Laser treatment for wet macular degeneration
Although most cases of wet AMD are treated with medication, in some instances thermal laser therapy may be used. Laser treatment is usually done as an outpatient procedure in the doctor’s office or at the hospital.
The laser beam in this procedure is a high-energy, focused beam of light that produces a small burn when it hits the area of the retina to be treated. This destroys the abnormal blood vessels, preventing further leakage, bleeding and growth.
Following laser treatment, vision may be more blurred than before treatment, but often it will stabilize within a few weeks. A scar forms where the treatment occurred, creating a permanent blind spot that might be noticeable in your field of vision.
Usually the abnormal blood vessels are destroyed by laser treatment. However, it is likely that 50 percent of patients with wet macular degeneration who receive this laser procedure will need a re-treatment within three to five years. You may be instructed to use the Amsler grid daily to monitor your vision for signs of change.
Photodynamic therapy (PDT)
In some cases, a type of treatment for wet macular degeneration called photodynamic therapy, or PDT, may be an option. This therapy uses a combination of a light-activated drug called a photosensitizer and a special low-power, or cool, laser to treat wet macular degeneration right at the centre of the macula.
This procedure is done on an outpatient basis, usually in an ophthalmologist’s office. The photosensitive drug is injected into a vein in your arm, where it travels through the body, including the abnormal vessels behind the central macula. The low-power laser light is targeted directly on the abnormal vessels, activating the drug, which causes damage specifically to those unwanted blood vessels.
After PDT, the abnormal blood vessels may reopen, so multiple treatments may be required.
What happens when macular degeneration cannot be treated?
It is important to remember that only about 10 percent of all macular degeneration cases are exudative, or wet form, and about 75 percent of these cases cannot be treated. People with wet or dry macular degeneration symptoms who cannot be treated will not become blind, as they will still have peripheral, or side, vision.
If you have untreatable macular degeneration, you can make the most of your remaining vision by learning to “see again” with the vision you do have and with the help of special low-vision rehabilitation, devices and services. People with low vision can learn new strategies to accomplish daily activities. These skills, including mastering new techniques and devices, help people with advanced AMD regain their confidence and live independently despite loss of central vision.
While there is little that can be done to improve the eyesight of someone who has AMD, with early detection, the rate of vision loss can be slowed. The keys to slowing vision loss are to understand macular degeneration, monitor your symptoms and visit your ophthalmologist regularly to test your vision. Even with macular degeneration, you can still maintain an enjoyable lifestyle.