Macular degeneration is a condition of the eyes which damages the retinas and results in loss of vision in the center of the visual field. It mainly affects older adults. People with macular degeneration usually retain enough peripheral vision to manage daily activities, although the loss of central vision can make it difficult or even impossible to read or recognize faces. There are two main forms of macular degeneration:

• dry (accumulated debris behind the retinas)
• wet (blood vessels growing up behind the retinas).

Symptoms of Macular Degeneration

If you think you might have macular degeneration, you should visit your doctor or ophthalmologist. Here are some of the symptoms that help doctors diagnose macular degeneration:

• blurry vision
• difficulty telling colors apart
• distorted vision
• shadows or missing areas in vision
• slow recovery of vision after bright light exposure.

Macular Degeneration Genetic Probability

Genetics play a large part in the development of macular degeneration. Macular degeneration studies have shown that people with a family history of macular degeneration have a 50 percent chance of developing this condition. People with no family history of macular degeneration have only a 12 percent rate of occurrence.

Scientists at Columbia University Medical center have discovered a genetic profile for macular degeneration. They found that the genes for proteins factor H (CFC) and factor B (CFB) are associated with macular degeneration risk. 74 percent of people with age-related macular degeneration have variants in these genes that increase their risk for this problem.

Other Macular Degeneration Causes

In addition to genetics, there are other factors that may increase macular degeneration risk. Some of these include:

• aging
• diet high in fats
• exposure to sunlight
• high blood pressure
• high cholesterol
• obesity.

Genetic Testing for Macular Degeneration

DNA tests are now available to identify increased risk for macular degeneration. Here is some information to help you decide if genetic testing is right for you:

• A negative test result can set your mind at ease if you are concerned about developing macular degeneration. Although it does not guarantee that you will not develop the condition, it shows that your risk is very low.
• A positive test result does not mean you will definitely develop macular degeneration. It only means that you are at higher risk.
• If you are found to have a high risk, you have the advantage of being able to take measures that may prevent or delay the onset of macular degeneration.

Preventing Macular Degeneration

Identifying genetic risk can help you preserve your vision. The Age-Related Eye Disease Study found that the risk of progressing from early to advanced stages of age-related macular degeneration could be reduced by about 25 percent through high doses of a combination of:

• beta carotene
• vitamin C
• vitamin E
• zinc.

Another study conducted at the National Eye Institute in Maryland found lutein and zeaxanthine (nutrients found in eggs and green vegetables) have a protective effect against macular degeneration. In addition to supplements, a healthy lifestyle, including a heart-healthy diet and exercise may help prevent macular degeneration.

Treating Macular Degeneration

While there is no treatment for dry macular degeneration, it usually progresses very slowly and nutritional supplementation helps to preserve vision. Wet macular degeneration has many treatment options:

• laser treatment
• medicine injected directly into the eye to stop growing blood vessels and prevent future vision loss (The eye is numbed of course!)
• photodynamic therapy
• surgery.

Hope for the Future

While there is currently no cure for macular degeneration, it is hoped that researchers will eventually find one through increasing genetic understanding of this condition. Studies on how siRNA (interfering RNA) can stop genes from carrying out their instructions have lead to promising new drugs that are currently being tested.  

Resources

 Cygene Laboratories, Inc. (2006). Glaucoma & Macular Degeneration DNA Analysis. Retrieved November 11, 2008, from the CyGene Direct Web site: https://cygenedirect.com/glaucoma/dna-testing_glaucoma_and_macular_degeneration.html.

Iconocast (2006). Age-related macular degeneration: two genes, Factor H and Factor B, involved. Retrieved November 11, 2008, from the Iconocast.com Web site: http://www.iconocast.com/News_Files/HNewsQ1_XX_XX/News4.htm.

Mayo Foundation for Medical Education and Research (2008). Macular Degeneration; Treatment. Retrieved November 11, 2008, from the MayoClinic.org Web site: http://www.mayoclinic.org/macular-degeneration/treatment.html.

Pollack, Andrew (2008). The Promise and Power of RNA. Retrieved November 11, 2008, from the New York Times Web site: http://www.nytimes.com/2008/11/11/science/11rna.html?_r=1&th&emc=th&oref=slogin.