Overview of mild, moderate and severe dry AMD including drusen and geographic atrophy.
The hallmark of dry AMD is macular drusen (see photo). Drusen are made up of lipids, a type of fatty protein. They may be the result of a failure of the eye to dispose of waste products that are produced when the photoreceptors of the eye drop off older parts of the cell. There are several types of drusen with different levels of risk. Drusen can be small, hard and scattered far apart from each other. They are round and distinct. This type may not create vision problems for a long time and may not even be an indication of macular degeneration.
Some drusen can become larger, softer and closer together. Their edges are less distinct. When they get to that stage, there is a greater risk for developing wet macular degeneration and more severe vision loss. They can also disrupt the layers of the retina and may lead to retinal pigment epithelium detachment (PED). Your doctor can see these drusen during a dilated eye exam, even if you are not aware of a vision change. That is one reason why regular eye exams are so important. If you have the larger, soft drusen, your doctor will probably want you to come into the office for check-ups more often. If they do lead to wet macular degeneration, early treatment is essential.
Geographic atrophy occurs when the photoreceptors (seeing part of the retina) no longer works and the patient develops a blind spot or spot of poor vision in the macula (see photo). Geographic atrophy (GA) is considered the late stage of the dry form of Age-related Macular Degeneration (AMD). It only occurs in about 10 percent of dry AMD patients. GA is usually a sharply delineated round or oval area of hypopigmentation, or apparent absence of the retinal pigment epithelium (RPE), in which choroidal vessels are more visible than in surrounding areas The most common sequence of events leading to GA is the progression of a large drusen to hyperpigmentation, followed by regression of the drusen, hypopigmentation and ultimately RPE cell death, with development of an atrophic area of retina and underlying choriocapillaris, sometimes preceded by the appearance of refractile deposits. This usually takes more than 5 years.
Less frequently, GA can follow a drusenoid RPE detachment, regression of a CNV membrane or a RPE rupture. As other forms of late AMD, GA tends to be bilateral (over 50% of cases) and there is high symmetry between eyes for total atrophic area, presence of peripapillary atrophy and enlargement rate. GA often first develops surrounding the fovea, sparing the central area.
Geographic atrophy can progress and lead to vision loss. When people with dry AMD lose vision, it is almost always from geographic atrophy. The animated image with this text shows growing geographic atrophy over 3 years in an 86 year old patient. This person is fortunate to have good vision because the dark areas of geographic atrophy are not yet affecting the central vision. Given the progression, the central vision will likely be affected within about 10 years. The images are fundus autofluorescent images that are useful for following geographic atrophy because the atrophy shows up as well delineated dark spots.
Pattern dystrophy is a type of dry age-related macular degeneration that involves mostly the very center of the macula. There are several types of pattern dystrophy. The image with this text is of a patient with adult vitelliform macular dystrophy. The image shows the buildup of abnormal deposits under the retina in the center of the macula. Unlike typical dry macular degeneration where the buildup of material is below the retinal pigment epithelium, in pattern dystrophy, the buildup of material is above the pigment epithelium and directly beneath the retina (see asterisks on image). Pattern dysrophy is autosomal dominant, usually presents at a younger age than typical dry AMD, and usually does not progress to wet AMD.
Patients who consume fruits and vegetables have the lowest rates of macular degeneration development. Lutein, a carotenoid pigment found exclusively in fruit and vegetables, serves as the primary protector of the eye. Lutein accumulates in the macula and likely blocks the damage caused by sunlight, one proposed cause of AMD. Fruits and vegetables are also high in antioxidant vitamins such as Beta- carotene, Vitamin E, and Vitamin C. Green leafy vegetables and other colorful foods like kiwi, squash, red grapes, and corn are good sources of Lutein. Other dietary habits have been shown to increase the risk of AMD. Individuals with a higher percentage of vegetable, monounsaturated, and polyunsaturated fats in their diet have higher rates of Wet AMD development. Diets rich in Omega 3 fatty acids reduce the risk of vision loss. These are found naturally in cold-water fish such as salmon and tuna, and in flaxseeds and flaxseed oil. Two servings of fish per week are adequate.
The Age-Related Eye Disease Study 2 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.
These vitamins contain a mixture of Vitamins C and E, Lutein, Zeaxanthin, Zing and Copper. Another large study in women showed a benefit from taking folic acid and vitamins B6 and B12. 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, 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.
One of the first signs of macular degeneration can be wavy, broken or distorted lines OR a blurred or missing area of vision. The Amsler Grid can help you spot these early. Early detection of wet AMD is critical because laser treatment, when indicated, is most successful when performed before damage occurs. Since dry AMD can lead to development of wet AMD, most patients should use the Amsler Grid. Check with your eye doctor to find out how often you should use this test.
Wear your reading glasses, if you normally use them and sit about 14 inches away from the screen. Check one eye at a time. Cover the eye you are not testing. Focus on the dark dot in the center of the grid. While looking at this dot, you still should be aware of the lines of the grid. Notice if any of the lines are distorted or broken or if there are blurred areas.
Below are current articles from a Google News Feed on Dry Macular Degeneration