What Is Macular Degeneration?
What happens when someone has macular degeneration, and the difference between the two types of it
Age-related macular degeneration (AMD) is the leading cause of adult vision loss in developed countries, with about 2.5 million new cases in the United States each year. If the person you're caring for has been diagnosed with AMD, it means that the area of his eye that provides central vision is beginning to deteriorate.
The good news is, no matter how advanced his AMD becomes, he won't go blind from it; he'll maintain his peripheral (side) vision.
The macula -- which is located in the retina -- senses light and helps you make out visual details. If someone has AMD, it means that the macula cells have stopped working and are dying off. Depending upon what kind of macular degeneration he has and how far it has progressed, he may have no symptoms or he may have partial or complete loss of central vision. The condition isn't painful, but it is progressive and can become debilitating. If your friend or relative has AMD in one eye, he's likely to get it in the other eye, too. (The National Eye Institute provides a helpful diagram of the eye, with definitions of its parts.)
Dry macular degeneration
You'll want to ask the doctor if the person you're caring for has "dry macular degeneration" or "wet macular degeneration." The dry (or atrophic) version accounts for about 90 percent of AMD cases and usually progresses slowly. Wet (also called exudative or neovascular) AMD typically advances more quickly and more often results in severe vision loss.
If he has dry AMD, it means that yellowish deposits of cellular waste, called drusen, are accumulating in his retina. (In a healthy eye, this waste is carried away by the same blood vessels that transport nutrients to the retina.)
At first he may not notice any effect on his vision, but as the drusen become larger, he may notice distortion in his central field of vision. He may also need increased light and contrast in order to see.
In the advanced stages of dry AMD, light-sensing cells and macula tissue begin to break down, causing a further loss of central vision. It's possible that with advanced AMD, he'll be left with peripheral vision only.
Wet macular degeneration
With wet AMD, new, immature blood vessels growing in the retina leak around the light-sensing cells. There are different classifications of wet AMD, depending upon where the leakage is occurring. In all cases, though, the bleeding can damage and scar tissues, quickly blocking vision.
Risk factors for macular degeneration
*Genetics Scientists have identified specific genes that raise the risk of AMD.
*Age The prevalence of AMD is 12.2 percent in those ages 55 to 64, 18.3 percent in those ages 65 to 74, and 29.7 percent in those over age 74.
*Obesity For those who have macular degeneration, being obese doubles the risk of developing a more advanced form of the disease.
*Smoking Smoking interferes with the body's absorption of lutein, an antioxidant that protects the retina. Smokers are two to five times as likely to develop macular degeneration as nonsmokers.
*Gender Some studies suggest that women are at higher risk of developing AMD.
*Race Caucasians are at higher risk than African Americans or Mexicans.
*Eye color Those with hazel or blue eyes seem to have a higher risk of developing AMD.
*Blood protein People with high blood levels of C-reactive protein may be at higher risk. High body mass index and smoking both increase C-reactive protein levels.