- central retinal degeneration
Macular degeneration is the leading cause of blindness in Americans over the age of 65. . 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.
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 rarely 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. Risk factors associated with a higher incidence of macular degeneration include:
- Caucasian race
- exposure to sunlight
- family history of macular degeneration
- female gender
high blood pressure
- high intake of
saturated fatsand cholesterol
- history of
- vascular disease, which includes diseases of the heart and blood vessels
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.
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, decrease the risk of progressive from dry to wet macular degeneration by 20%. However, their effectiveness has not been proven. Avoidance of smoking may lower a person's risk.
How is the condition diagnosed?
Diagnosis of macular degeneration begins with a medical history and physical exam. A healthcare professional 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.
Long Term Effects
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 to drive and cannot read without bright light and magnification.
What are the treatments for the condition?
Despite ongoing research, there is no cure for the dry form of macular degeneration. Findings from recent studies suggest that
antioxidant vitamins and minerals may slow the progress of the condition. The National Eye Institute recently conducted a large study to determine the effectiveness of such treatments, with encouraging results.
Dry macular degeneration is also 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:
- closed-circuit television
- large-print reading materials
- magnifying devices
- talking or computerized devices
The wet type of macular degeneration can sometimes be treated with
laser surgery, photodynamic therapy, or injecting the drugs into the eye. 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 (i.e., Visudyne) is given through an intravenous line. A laser is then used to close the abnormal blood vessels.
More recently, the injection of biologic drugs which inhibit the growth of abnormal blood vessels under the macula have shown the best effect. These two drugs are called bevacizumab (i.e., Avastin) and ranibizumab (i.e, Lucentis). Monthly injections into the eye may be needed for up to two years. These injections, given in the office, will stabilize or improve vision in up to 85% of patients.
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?
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 an Amsler grid. The healthcare professional should be notified immediately of any changes in vision. Any other new or worsening symptoms should also be reported to the healthcare professional.