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. These 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 sharp vision that enables you to see small detail, read fine print, recognize faces, and see signboards.
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 is often known as age-related macular degeneration (AMD). AMD is the leading cause of vision loss in people over the age of 50 around the world.
Causes of age-related macular degeneration
The precise cause of age-related macular degeneration is unknown to the medical fraternity. However, there are some risk factors including:
- Genetic factors
- Nutritional factors
- High blood pressure
- Exposure to direct sunlight over a period of years
- Certain medical conditions
There are two types of age-related macular degeneration
, the dry and the wet form.
The dry form affects about 85-90 percent of 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.
The wet form occurs in about 10-15 percent of 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 normally causes major vision problems
, such as blind spots and loss of central vision, in the affected eye, and can advance rapidly.
Age-related macular degeneration doesn't have symptoms and is not recognized until it affects vision. The first symptom of this eye disease is usually noticed when straight lines appear wavy. This may lead to a gradual loss of central vision. Other symptoms include:
- Blurring and dimming of vision
- A dark or blank spot in the centre of the vision
- The size or colour of something looks different when viewed through different eyes
Although there is no treatment to reverse the dry form of age-related macular degeneration, eyesight may be helped with low-vision aids, e.g., devices that have special lenses that produce enlarged images of nearby objects. They help people with partial vision make the most of their remaining vision.
Several options are available to treat the wet form of age-related macular degeneration, but not all are appropriate or successful for all patients. These treatments include:
- Anti-angiogenesis medications: There are several drugs that prevent the growth of abnormal blood vessels. These drugs are injected into the eye to cause the blood vessels to shrink. This treatment may improve vision in some patients and stabilize it in most patients.
- Photodynamic therapy: The eye doctor injects a light-sensitive drug into the bloodstream to be absorbed by the abnormal blood vessels in the eye. He/She then shines a cold laser into the eye to activate the drug, damaging the abnormal blood vessels.
- Laser therapy: High-energy lights are used to destroy actively growing abnormal blood vessels.
Unfortunately, age-related macular degeneration can return even after successful treatment. The various treatments can slow the rate of vision loss and hopefully preserve some sight.