Overview, Causes, & Risk Factors
Macular degeneration is an eye disorder caused by breakdown of the macula. The macula is the center of the retina at the back of the eye. The images we see are sent to the macula and the rest of the retina. The macula has been compared to the film of a camera because it stimulates the brain so that we “see” the image in our mind.
There are two common types of age-related macular degeneration: the dry or atrophic form and the wet or exudative form. Dry macular degeneration is the most common type. It is caused by the gradualthinning of the macula as a result of aging. A number of small, round sores form under the outer layer of the retina. Over time, these sores multiply and form together, impairing vision.
Wet macular degeneration accounts for only about 10% of cases. It occurs when tiny, abnormal blood vessels form under the retina. These vessels leak fluid or blood, which causes blurring of the central vision. Vision loss may be rapid and severe.
What is going on in the body?
The macula is the most critical portion of the retina. It is responsible for detailed vision. This function is necessary for reading and seeing distant objects in detail. When the macula is damaged, vision is affected. Most of the time, this breakdown is age related. It can also occur in younger people who have a genetic tendency toward the condition.
What are the causes and risks of the condition?
Macular degeneration affects more than 25 million people worldwide. Most of the time, it occurs as part of normal aging. Thirty percent of people over age 75 have macular degeneration.
Risk factors associated with a higher incidence of macular degenerationinclude the following:
A recent study has identified a gene named ELOVL 4 that is associated with the form of macular degeneration that occurs in adolescents. The gene may also be associated with the age-related form of macular degeneration. More research is needed in this area.
Symptoms & Signs
What are the signs and symptoms of the condition?
Macular degeneration reduces vision in the center of the field of vision. It does not affect the eye’s peripheral or side vision. This means a person will be able to see large objects well. For example, a person may be able to see the outline of a clock but may not be able to tell what time it is. Activities such as threading a needle or reading may become difficult or impossible.
People with macular degeneration may see objects as smaller or larger than they really are. For some people, the condition causes a dark or empty area in the center of the field of vision. For others, straight lines look distorted. Each eye may see a shape or color differently.
Diagnosis & Tests
How is the condition diagnosed?
Diagnosis of macular degeneration begins with a medical history and physical exam. A healthcare provider can detect the problem by dilating the person’s pupil and looking at the back of the eye. In another test, individuals look at a grid resembling graph paper. This is called an Amsler grid. If some of the lines appear lost or distorted, a problem with the retina exists.
A fluorescein angiogram is a test in which special photographs are taken of the back of the eye. The test can reveal abnormal vessels under the retina. Indocyanine green angiography uses different wavelengths of light. It detects the sores related to dry macular degeneration.
Prevention & Expectations
What can be done to prevent the condition?
Unfortunately, macular degeneration is not well understood. There are no known prevention methods. Certain vitamins and minerals, such as vitamin E, vitamin C, and zinc, mayslightly decrease the risk of developing this condition. However, theireffectiveness has not been proven. Avoidance of smoking may lower a person’s risk. Following a heart-healthy diet may decrease the risk associated with heart and vascular disease.
What are the long-term effects of the condition?
With dry macular degeneration, central vision is gradually reduced over many years. Sometimes the condition will be stable for a number of years without worsening. In wet macular degeneration, vision may decrease suddenly. If this happens in one eye, the other eye should be carefully monitored.
There is a marked loss of central vision in advanced macular degeneration.People tend to become frustrated with their condition. They are unable todrive and cannot read without bright light and magnification.
Treatment & Monitoring
What are the treatments for the condition?
Despite ongoing research, there is no cure for the dry form of maculardegeneration. Findings from recent studies suggest that cancer\ \
At present, dry macular degeneration is managed by helping the person cope with the condition. Optical devices can sometimes be used to take advantage of a person’s side vision. Low-vision aids such as these can also help affected individuals:
The wet type of macular degeneration can sometimes be treated with laser surgery. This is an option for only about 25% of people with the condition. It is a brief and painless procedure done in a short-stay surgery setting. A laser beam is used to seal the leaking blood vessels that are damaging the macula. This leaves a small permanent scar or blind spot at the point of laser contact. However, more sight is preserved overall.
The FDA recently approved a procedure called photodynamic therapy. A light-activated medicine called verteporfin is given through an intravenous line. A laser is then used to close the abnormal blood vessels.
What are the side effects of the treatments?
Medicines used to treat macular degeneration may cause stomach upset and allergic reaction. Surgery may cause scarring of the retina and blind spots where the laser procedure was performed. It may also cause bleeding, infection, or allergic reaction to anesthesia.
What happens after treatment for the condition?
Laser surgery may need to be repeated every 1 to 2 years if the blood vessels open back up. A person may need to adjust his or her routine in response to decreased vision.
Macular degeneration does not result in total blindness. Most people continue to have some useful vision. They are able to take care of themselves until the condition is very advanced. Also, vision is sometimes reduced in only one eye. The other eye may be able to see well for many years. When both eyes are affected, the individual will notice the problem more quickly.
How is the condition monitored?
People with macular degeneration can check their vision daily by using anAmsler grid. The healthcare provider should be notified immediately of any changes in vision. Any other new or worsening symptoms should also be reported to the healthcare provider.
Article type: xmedgeneral