By Carol Duff, MSN, BA, RN
Today AMD is considered to be incurable as its disease process causes a destruction of the central portion of the retina, which lines the back, inside portion of the eye.
The retina is the inner layer of the eye and is sensitive to light. When light, which travels through the front of the eye, and continues through the lens, and is focused on the retina, the retina, in response to this stimulation starts a series of chemical and electrical events that trigger the nerve impulses. Think of the retina as being film in a camera. The electrical impulses are then sent to the visual centers of the brain via the optic nerve.
The macula of the eye, which is responsible for creating central vision in the eye and in doing so controls our ability to drive a car, to recognize colors and objects and to see those objects in fine detail. In AMD the central portion of the retina, which contains the macula is slowly destroyed. The macula is also responsible for the very important process of reading. Symptoms of this disease may include blurry and dark or white areas in the center of your vision with or without alteration in perception of color.
The detail of an object (think of a picture with tons of pixels), is created in the macula which is the center of the field of vision. If cells of the macula are disrupted or deteriorate, the image is not received correctly. The very early stages of this disease do not cause a noticeable change in vision. As Macular Degeneration progresses, you will experience blurred or vision that looks wavy. Faces may seem blurry, adjusting from bright light to dim light becomes difficult, impaired depth perception, sensitivity to light increases, night vision improves, or threading a needle or other close work becomes impossible. As the condition worsens, the central part of what you see will be gone and if very advanced, people with this disease are considered to be legally blind with vision scores of 20/200.
While you may be able to see the edges of what you are looking at, the middle portion will disappear. Macular Degeneration seldom leads to complete blindness, but creates substantial visual disabilities. AMD does not cause pain.
Types of Macular Degeneration
The two main types of Macular Degeneration are “wet” and “dry.” About 85% to 90% of the cases are the dry (atrophic) type which progresses more slowly, and 10% to 15% are the “wet” (exudative) type. Wet AMD is caused by the process of angiogenesis. Normal angiogenesis (growth of new blood vessels) occurs in healing of wounds and reproduction. Abnormal angiogenesis occurs when unnecessary new blood vessels grow under the macula and disrupt this region of the retina.
These is also Stargardt disease which is found in young people and is caused by a recessive gene inherited from mother, father, or both parents.
Stages of Age-related Macular Degeneration (AMD)
In Early AMD, most people do not experience vision loss. If you have a risk factor, regular eye examinations are essential. Risk factors are:
- Age, because this disease is more likely to occur in those 55 and older.
- Genetics, with a family history of AMD giving a higher risk.
- Race, with Caucasians having a greater incidence than African-Americans or Hispanics/Latinos.
- Smoking, which doubles the risk.
- Women are more likely than men to develop AMD.
- Obesity increases the progression of early and intermediate AMD to advanced AMD.
- Uncontrolled high blood pressure increases the risk of developing AMD.
The presence of medium-sized drusen (yellow deposits under the retina) will be found.
In Intermediate AMD there will be some vision loss but the symptoms may not be that noticeable. Larger drusen and/or pigment changed will occur in the retina.
In Late AMD vision loss will be very noticeable.
What Causes AMD?
The causes are complex and do not point to any particular reasons. Your heredity and environment have played a factor in your contracting this disease. Funding for this illness is sparse but those who have researched the reason for the cause are working to understand why the cells of the macula deteriorate. When the action or cause of this disease is discovered, only then a cure can be formulated. What is known is that Stargardt disease has a particular genetic cause while AMD has both genetic and environmental components.
It is estimated that there will be 6.3 million Americans affected by the year 2030. AMD will reach epidemic proportions as the baby boomer generation ages. Lack of treatment advances also contribute to this dire warning.
Who will you see if you have AMD ?
You will see an ophthalmologist who is a medical doctor who specializes in diseases and treatment of the eye. Your vision will be checked, including a view within your eye, with an ophthalmoscope, to assess the retina. You may also be asked to look at an Amsler grid which is a pattern of straight lines, much like a checkerboard. If the lines look wavy or some seem to be missing, this could be a sign of Macular Degeneration.
You may be tested with an Optical Coherence Tomography (OCT), which is a special photograph that shows a magnified 3D image of the retina. This gives a precise picture of the health of your retinas.
Another test may be fluorescein angiography which will show the condition of the blood vessels of the retina. A dye will be injected into a vein in your arm and pictures will be taken to look for leaking blood vessels or blood in the macula.
Macular Degeneration at this time has no cure, but is treated with visual aids, vitamins, and laser therapy and the following processes.
Anti-angiogenic drugs Medications are injected into the eye to block the formation of new blood vessels and stop the leaking from the abnormal vessels and is used for wet macular degeneration.
Photodynamic Laser Therapy is a two-step process that uses a light-sensitive drug to destroy the abnormal blood vessels.
Laser Therapy may be used to destroy the abnormally growing blood vessels. A medication will be injected into your bloodstream and will target the abnormal blood vessels in the retina. A laser will be shined into your eye to activate the drug and destroy the blood vessels.
Vitamins can be prescribed. According to a study by the National Eye Institute of the National Institutes of Health, called AREDS (Age-Related Eye Disease Study), Vitamins C and E, beta-carotene, zinc, and copper may decrease the risk for vision loss for some with intermediate to advanced dry AMD types.
An updated formula, AREDS2, added zeaxanthin, omega-3 fatty acids, lutein and removed beta-carotene, which might be safer for smokers since beta-carotene is connected to a higher risk of lung cancer in people who smoke.
Low Vision Aids offer special lenses or electronic systems that enlarge images.
Researchers are always studying new ways to treat age-related macular degeneration. Some experimental methods are:
Submacular surgery is performed when a surgeon removes the scar tissue, blood, and abnormal blood vessels from the eye.
Retinal translocation which is a procedure that destroys the abnormal blood vessels that are under the center of the macula, after first rotating the macula center away from the abnormal blood vessels, thus protecting the macula center, the physician uses laser to treat the abnormal blood vessels.
You can have AMD in only one eye. Eye exams will be completed for both eyes, to catch any changes in the non-affected eye. The key is to test your vision for any changes. Some who have the dry form of AMD can develop the wet form. If you have the wet form of macular degeneration, even if you are receiving treatment, you should test your vision for any blind spots which may become larger and for new blind spots. Even if you have had laser treatment or injections to destroy abnormal blood vessels, new blood vessels can form months or even years later. The correct treatment option can help you to maintain your sight.
Prevention and Taking Control of Your Eye Health
- The earlier the diagnosis of AMD, the better the chance you have for treatment to help.
- Immediately seek help from a health care professional who specializes in treatments and/or surgery of the eye (ophthalmologist) if you notice any of the signs or symptoms listed in this article.
- See your eye doctor for regular eye exams.
- Stop smoking.
- Protect your eyes with sunglasses which block the harmful ultraviolet (UV) rays.
- Eat a balanced diet which includes leafy green vegetables.
- Use supplements (after first discussing with your doctor) with antioxidants plus zinc.
- Your vision exams, if you are over 65, should include testing for AMD.
- Take excellent care of your eyes, because they are the only ones you will ever have.