Age-related macular degeneration is the leading cause of vision loss among Americans age 65 and older, according to the American Macular Degeneration Foundation. More than 10 million people suffer from the disease, in which the portion of the retina responsible for capturing fine details and color suffers pathological changes. As the macula deteriorates, it causes blurred or reduced central vision.
Macular degeneration is best evaluated and treated by retina specialists, who are ophthalmologists with special training and expertise in disorders of the retinal region. Anyone that has suffered the visual effects of macular degeneration should seek out an experienced retina specialist for their medical and surgical care.
What Causes Macular Degeneration?
Experts don’t know what exactly causes the macula to break down, but there are theories. Some believe that the retina — particularly the macula — is vulnerable to oxidative stress, or an imbalance in the production of free radicals and the body’s ability to counteract their harmful effects. The retina consumes a large amount of oxygen, has a high concentration of photosensitive cells and is constantly exposed to focused light, which puts it at an increased risk of oxidative stress. The aging process destroys the natural levels of lutein and zeaxanthin, two vision-protective pigments. This affects the eye’s natural ability to fight oxidative stress, and progressively destroys the retina. Eventually, fine details and colors become difficult to see.
There are two types of macular degeneration:
Dry (non-neovascular) macular degeneration is the earlier and more common form of the disease. Between 85 and 90 percent of cases are the dry type. In dry macular degeneration, the layers of the macula gradually thin and atrophy. Yellowish spots called drusen start to accumulate in and around the macula. Drusen are tiny piles of debris from the deteriorating tissues that sometimes cause further retinal deterioration and atrophy.
People with dry macular degeneration may experience gradual loss of central vision, but it is generally not as severe as that of the wet form of the disease.
About 10 percent of cases advance to the wet form of the disease. Wet (neovascular) macular degeneration is more likely to lead to serious vision loss. People with wet macular degeneration grow new blood vessels in their retina; the vessels are weak and leak blood and other fluids in between the layers of the retina. The leakage can cause scar tissue to form — creating a dark spot in the vision — and the retina cells stop functioning.
Depending on the stage of the disease, symptoms can include:
- Blurred or fuzzy vision
- Straight lines that appear wavy
- Objects appearing smaller than they actually are
- The appearance of a gray, dark or blind spot in the center of the field of vision
- Colors looking paler than normal
Diagnosing Macular Degeneration
Macular degeneration is detected in an eye exam. The doctor dilates the eyes to get a closer look at the retina and the macula. In the early stages of the disease, the doctor can spot drusen or other particles on the surface of the retina. People with macular degeneration may have many drusen. The color of the macula may also look different if it has started to degenerate.
In addition to looking at the back of the eye, the doctor also tests for visual distortions using an Amsler grid. The grid is composed of straight lines; to someone with macular degeneration, the lines can look wavy or distorted.
The doctor may perform a fluorescein angiography, in which a colored dye is injected into the arm and travels to the eye, highlighting the blood vessels. The images from the test show abnormalities in the blood vessels and changes in the retina. Another imaging test that is used to diagnose macular degeneration is an optical coherence tomography, which shows cross-sectional images of the retina, identifying areas that are thinning, thickening or swelling.
If a macular degeneration diagnosis is confirmed, the doctor can outline the macular degeneration treatment options. There is no cure for macular degeneration, but there are ways to manage it. In the early stages, taking certain supplements, eating the right foods and quitting smoking can help slow the disease’s progression. In the later stages where vision is severely impacted, working with a low vision rehabilitation specialist can help the patient adapt to vision changes.
Learn More about Macular Degeneration
If you have questions about macular degeneration, its causes or symptoms, we invite you to contact our retina specialists today. Request an appointment at our practice to speak with a member of our team.