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Macular Degeneration

What is it?

    One can liken the eye to a camera. In a camera, light is focused on film and in the eye, light is focused on the retina. Akin to camera film the retina is located in the back of the eye and takes the picture of what you are seeing. Unlike camera film only one portion of your retina is capable of sharp vision and this region is called the macula. When this portion of the retina deteriorates, the process is called macula degeneration. If the macula is diseased one can still see to the side and peripheral vision is maintained; however this portion of the retina is not capable of fine vision. Reading normal sized print, sewing, easily viewing a computer screen and seeing well enough to legally drive can become compromised if the macula is significantly diseased in both eyes. Nonetheless even when macular degeneration is advanced peripheral vision remains.  An individual can become legally blind from this disease, but one does not lose all eyesight even if the degeneration is extensive. One eye is often worse than the other is, however both eyes are effected in most individuals if they have had the disease for a number of years. It is unusual for an individual with even severe macula degeneration to reach the point where they can not see well enough to get around the house, eat and dress.

The Significance of This Disease

     Age Related Macular Degeneration (AMD) does not have the successful treatment modalities that cataracts and glaucoma enjoy, and so in the United States this disease is the commonest cause of blindness in people over 55.  It effects over ten million Americans and 1.5 to 2 million have significant visual impairment. Nearly 30 percent of people over the age of 75 years have some eye changes associated with AMD, and about 7% have significant visual loss. Because macula changes become more common as the eye ages this disease will be more significant as our population becomes older.

The Two Types of AMD:

    About 90% of individuals have what is referred to as the dry type of AMD. When examining the retina one sees degenerative spots called drusen, retinal thinning, and pigmentary abnormalities. In most patients visual impairment is gradual over the years, and often not severe.

    The second type of macular degeneration is called wet or exudative degeneration. Here drusen are often the first signs of the disease, however unlike the dry type of degeneration abnormal blood vessels grow just behind the macula. This is called choroidal neovascularization. These vessels are not normal or healthy and consequently tend to leak fluid into the retina and at times small hemorrhages occur. This bleeding frequently causes rapid loss of central vision, and after the blood has reabsorbed often a scar results. This scar replaces the macula, and central visual loss can be profound.

Causes or Etiology:

    The cause of the common age-related macular degeneration is not known. Heredity sometimes plays a role, and smoking is a definite risk factor. It is more common in fair skinned individuals and in those with blue eyes, however it does occur in all races. Above average exposure to sunlight and nutritional factors may be contributory. Individuals that are very myopic (nearsighted) are at greater risk for macula disease, and some types of drugs can damage the macula.

Prevention Strategies:

The current state of the art does not provide completely successful treatment or restorative modalities in either form of macula degeneration so prevention is important.

1. There is a  relationship between smoking and macula degeneration and if you smoke make every effort to stop

2. The national Age-Related Eye Disease Study (AREDS) reported in October 2001 that high levels of antioxidants and zinc significantly reduced the risk of advanced AMD by about 25 percent. These same nutrients also reduced the risk of vision loss caused by advanced AMD by about 19 percent. This treatment did not restore vision once lost, and the dietary supplements did not prevent the development or progression of cataracts. The current recommendation (AREDS 2) are Vitamin C:  500 mg;  Vitamin E:  400 IU;  Luetin: 10 mg;   Zanthine: 2 mg;  Zinc:  20 mg and Copper:  2 mg. People who are at high risk for developing AMD and those that already have the disease should consider taking this formulation. ,  If you are already taking dietary supplements this regime may not be indicated, or it might require modifications. Speak with me when you visit. This data was summarized from the National Eye Institute web site and please visit them for all of their Age-Related Eye Disease Study reports.

3. Wear UV absorbing sunglasses. Light is focused on the macula by the eye’s optics and too much light can damage the macula even in normal individuals.

4. Vegetables such as spinach and collard greens contain carotenoids that are precursors of Vitamin A. Luetin and  zeaxanthin are pigments in the macula that are also in these foods. Some believe that eating more of these types of vegetables may help prevent or retard the progression of macular degeneration. If none are in your diet and you have macula changes this strategy is reasonable. Drinking wine probably does not help despite some reports touting its value several years ago. Antioxidant vitamins and mineral supplements are believed by some to also be beneficial. 

5. Early diagnosis of the wet type of macular degeneration is important because new treatment modalities can be quite beneficial, especially when started early in the course of the disease.

Symptoms of the Disease:

    In both types of the disease often the first signs are a distortion in vision. Drusen can cause a small bump in the retina and if blood vessels are leaking the retina will be distorted. If straight lines are irregular, or there is a dark or blurry spot in your visual field it is important to see an Ophthalmologist without delay. A useful patient screening tool is the Amsler Grid. This is essentially a sheet of graph paper with a dot in the middle. Distorted grid lines can signify a macular problem. For people at risk, looking at the grid periodically can help make an early diagnosis. If you have the disease a change in the eye’s status is often first discovered this way.

Treatment:

    For both types of macula degeneration the prevention strategies discussed above are important.

    For the dry type of macular degeneration vitamins  and dietary supplements are  useful. If you smoke it is important to stop. Macula degeneration is about five times commoner in smokers than in non-smokers.

    The current mainstay of treatment for the wet type of macular degeneration is by using a type of drug called an anti vascular endothelial growth factor or anti VEGF for short.  These medications work by inhibiting the growth of abnormal blood vessels in the retina. These capillaries are the ones that leak fluid and blood cells into the retina which in turn leads to the loss of vision in this disease.  Macugen® (Pegaptanib), Lucentis® (Ranibizumab) and Eylea^® (aflibercept) ,  have been approved by the  Food and Drug Administration (FDA)  for wet macular degeneration and a third drug Avastin® (Bevacizumab) also works well for this condition however it has not been approved by the FDA for ocular use. These drugs are proving effective in not only preventing progressive visual loss, but in a significant number of patients vision actually improves after treatment. Lucentis, Eylea and Avastin are becoming the most commonly utilized and The National Eye Institute is sponsoring studies  to determine which of these three drugs works best.  Laser treatment for this type of macular degeneration is being used less because for most patients the anti VEGA drugs provide a better prognosis (probability) for  preservation and even  improvement of vision.

Links to Web  Resources:

    The American Macula Degeneration Society is a non-profit organization offering general information about prevention, diagnosis and treatment.  Information about the disease is factual and straightforward. An Amsler Gridcan be downloaded. There is a section on health tips and a list of medications that can damage the macula.  The site features a Care and Services Directory with useful references such as a listing of state agencies offering services to the visually impaired.

      The National Eye Institutes Page on Macular Degeneration provides  information and links for further study. Their pamphlet on Age Related Macula Degeneration provides an easily read synopsis.  It provides very basic information about what the disease is, risk factors, diagnosis, treatment, and a short reference section to other sites.