What is Macular Degeneration?
The retina is a light-sensing tissue located at the back of the eye. The central portion of the retina is called the macula, and this area is responsible for central vision. When certain macular cells begin to deteriorate, it is called macular degeneration.
Because the macula is at the center of the retina, when it fails a person loses sight in the center of their visual field. The peripheral vision usually remains normal.
What is macular degeneration?
Macular degeneration is the leading cause of vision loss in the U.S., ahead of glaucoma and cataracts combined.1 People with macular degeneration do not usually go completely blind, but do have trouble seeing faces, driving, reading, writing, doing close work, or any other activity that requires sharp central vision.
What are the types of macular degeneration?
Age-related macular degeneration
There are two types of age-related macular degeneration:
- Dry (atrophic) macular degeneration is by far the most common, occurring in 80-90% of cases.1,2
- Wet (exudative) macular degeneration strikes in only 10-20% of cases. It is less common but much more serious. 1,2
Within these two main types, the severity can vary greatly depending on various factors such as genetics, environment, and age.
Stargardt disease, also called Stargardt macular dystrophy or juvenile macular degeneration, is the most common inherited macular dystrophy for both adults and children and affects one in 8,000-10,000 individuals.3 Often times, vision loss slowly occurs during childhood or adolescence, but for some individuals, it may not occur until adulthood, such as in patients with fundus flavimaculatus.
Myopic macular degeneration
Myopic macular degeneration (MMD), also known as pathological myopia or degenerative myopia, is closely associated with choroidal neovascularization (CNV), which is the leading cause of visual impairment in those younger than 50 in the US.4 In highly myopic, very nearsighted, eyes, the ocular tissues (retina and choroid) are gradually stretched as the eye elongates. In some individuals, this stretching may lead to structural damage.
What causes macular degeneration?
Age-related macular degeneration
For the most part, doctors do not know what causes age-related macular degeneration. Here is what they do know:
- Dry age-related macular degeneration (AMD) is the most common type and involves the gradual deterioration of macular light-sensing cells. Scientists believe that genetic, environmental, and other factors may play a role in the development of dry AMD.
- Wet AMD occurs when abnormal blood vessels grow underneath the retina. These vessels tend to leak fluid or bleed, causing damage and distortion of the macula resulting in vision loss.5
Stargardt disease is a hereditary form of macular degeneration that typically begins in childhood or adolescence is caused by a recessive gene mutation.
Myopic macular degeneration
Myopic macular degeneration (MMD) sometimes occurs in people who are extremely near-sighted (high myopia) and it tends to run in families. Patients with MMD can also develop abnormal, leaky blood vessels similar to those seen in wet AMD, called choroidal neovascularization (CNV).6
Are there common risk factors?
- Age is the most common risk factor for macular degeneration. It appears most often in people who are 50 and older.1,2
- Individuals who have a family member with macular degeneration are more likely to develop the disease.
- Caucasians develop the disease more often than African Americans or Hispanic/Latinos.
- Being overweight, having a diet high in fat, or having high blood cholesterol levels also put you at higher risk of developing AMD.
- Smoking doubles the risk of developing AMD.1,2,7
What are the symptoms and how is it diagnosed?
Most people with macular degeneration first notice a lack of detail in the center of their vision, blurry spots or dark areas. To diagnose macular degeneration, your ophthalmologist (eye doctor) will use a variety of tests. Most commonly, your doctor will dilate, or widen, your pupils and look at the back of your eye using a special lens.
Other tests to diagnose macular degeneration include:
- Fluorescein angiography. A yellow dye (called fluorescein) is injected into a vein, usually in your arm. The doctor then uses a special camera to take photos of the dye as it travels through the blood vessels in the back of your eye. This test allows your doctor to tell if there are new, abnormal blood vessels growing under the retina.
- Optical coherence tomography (OCT). Similar to an ultrasound, but instead this test uses light to take detailed cross-sectional pictures of your retina and macula.
Doctors recommend regular eye exams so that macular degeneration can be caught as early as possible.
How is it treated?
There is currently no cure for macular degeneration, but there are some lifestyle changes and treatment options that may help to slow the progression of the disease.
There is no proven treatment for early or late dry AMD, however there are lifestyle changes you can make that may help slow disease progression. Additionally, a large study called AREDS 2 (Age-Related Eye Disease Study 2) showed that those with intermediate dry AMD may be less likely to develop advanced AMD if they took the following supplements2:
- Vitamin C (500 mg)
- Vitamin E (400 IU)
- Lutein (10 mg)
- Zeaxanthin (2 mg)
- Zinc (80 mg)
- Copper (2 mg)
Wet AMD and MMD
Wet AMD and CNV in myopic macular degeneration is treated with drugs called anti-VEGF medicines. These drugs help reduce the number of abnormal blood vessels growing in the retina and also decreases fluid leaking of fluid from those vessels.2
Unfortunately, right now, there is no treatment for Stargardt disease. Research is being done on gene therapies and drug therapies, as well as stem cell therapies. There are also some protective measures you can take to slow down the progression of the disease.