What is macular degeneration?
The front of the eye contains a lens that focuses images on the retina in the back of the eye. The retina contains special nerve cells that react to light.
Nerve cells are very close together in the middle of the retina, where the eye focuses the images that we see. This part of the retina is called the macula. The macula provides the sharp, straight-ahead vision that allows you to see small detail, read fine print, recognize faces and see street signs.
Macular degeneration is an eye disease and is the most common type of macular damage in adults. Because the disease develops as a person ages, it's often called age-related macular degeneration (AMD). AMD is the leading cause of vision loss in people over the age of 50 in the United States, Europe and many other parts of the world.
What are the types of age-related macular degeneration?
There are two types of AMD – the dry (atrophic) form and the wet (exudative or neovascular) form.
The dry form of AMD affects about 85-90% of AMD patients and usually begins when tiny yellow deposits called drusen appear in the macula. Drusen usually do not cause serious loss of vision, but can distort vision. However, for reasons not yet understood, sometimes drusen are associated with macular atrophy (thinning) and tissue breakdown, slowly leading to vision loss. Patients may have blind spots in their vision; in the advanced stages, patients may even lose central vision.
The wet form of AMD occurs in about 10-15% of AMD patients. It is caused by the growth of abnormal blood vessels beneath the macula that can leak fluid and blood into the eye. The wet form of AMD usually causes major vision problems, such as blind spots and loss of central vision in the affected eye, and can advance rapidly. These abnormal blood vessels eventually scar, leading to permanent retinal damage and loss of central vision.
Most patients with AMD have the dry form of the disease and will not lose central vision. However, the dry form of AMD can lead to the wet form. People who have the wet form of AMD are much more likely to have serious vision loss. For these patients, early diagnosis and treatment are important to save as much vision as possible.
Because the dry form can change into the wet form, it's very important for people with AMD to monitor their eyesight carefully and see their eye doctor on a regular basis.
AMD may be hereditary, meaning it can be passed on from parents to children. If someone in your family has or had the condition, you may be at higher risk for developing the disease. Talk to your eye doctor about your individual risk.
What causes age-related macular degeneration?
The exact causes of macular degeneration aren't known. Risk factors may include:
- Genetic factors.
- Nutritional factors.
- High blood pressure.
- Exposure to direct sunlight over a period of years.
- Certain medical conditions.
What are the symptoms of age-related macular degeneration?
AMD often doesn't have symptoms and isn't recognized until it affects visual acuity (sharpness). The first symptom of AMD is usually noticed when straight lines appear wavy. This may lead to a gradual loss of central vision.
Other symptoms of AMD include the following:
- Blurriness and dimming of vision.
- A dark or blank spot in the center of the vision.
- The size or color of something looks different when viewed through different eyes.
If you have any of these symptoms, see an ophthalmologist (eye doctor) as soon as possible.