What Is Macular Degeneration (AMD)?

Macular degeneration is a condition that damages the macula, the central part of the retina. The macula is responsible for central vision and the ability to see detail.

When the macula is damaged, the eye loses its ability to see detail, such as small print, facial features or small objects. The damaged parts of the macula often cause scotomas, or localized areas of vision loss. When you look at things with the damaged area, objects may seem to fade or disappear. Straight lines or edges may appear wavy.

What Are the Different Types of Macular Degeneration?

There are two types of the disease: dry macular degeneration and wet macular degeneration.

The image below to the right is what someone may see with macular degeneration:

Dry macular degeneration

Dry macular degeneration is a chronic eye disease that causes vision loss in the center of your field of vision. Dry macular degeneration is marked by deterioration of the macula, which is in the center of the retina — the layer of tissue on the inside back wall of your eyeball.

Dry macular degeneration is one of two types of age-related macular degeneration. The other type — wet macular degeneration — is characterized by swelling caused by leaky blood vessels in the back of the eye. Dry macular degeneration isn't associated with swelling and is the more-common form of the disease.

Dry macular degeneration doesn't cause total blindness, but it worsens your quality of life by blurring or causing a blind spot in your central vision. Clear central vision is necessary for reading, driving and recognizing faces.
 
Symptoms

Dry macular degeneration symptoms usually develop gradually. Typically there are no symptoms but you may notice:

• The need for increasingly bright light when reading or doing close work
• Increasing difficulty adapting to low light levels, such as when entering a dimly lit restaurant
• Increasing blurriness of printed words
• A decrease in the intensity or brightness of colors
• Difficulty recognizing faces
• A gradual increase in the haziness of your overall vision
• A blurred or blind spot in the center of your field of vision
• Hallucinations of geometric shapes or people, in cases of advanced macular degeneration

Dry macular degeneration may affect one eye or both eyes. If only one eye is affected, you may not notice any or much change in your vision because your good eye compensates for the weak one.

Wet macular degeneration

Wet macular degeneration is marked by swelling caused by leaking blood vessels that affect the macula (MAK-u-luh), which is in the center of the retina — the layer of tissue on the inside back wall of your eyeball.

Wet macular degeneration is one of two types of age-related macular degeneration. The other type — dry macular degeneration — is more common and less severe. Wet macular degeneration almost always begins as dry macular degeneration. It's not clear what causes wet macular degeneration to develop.

Early detection and treatment of wet macular degeneration will often reduce the extent of vision loss and, in some instances, improve vision. This is key to maintaining your vision with AMD.

Types of wet macular degeneration
Wet macular degeneration can develop in different ways:

• Vision loss caused by abnormal blood vessel growth. The choroidal neovascularization type of wet macular degeneration develops when abnormal new blood vessels grow from the choroid — the layer of blood vessels between the retina and the outer, firm coat of the eye called the sclera — under and into the macular portion of the retina. These abnormal vessels leak fluid or blood between the choroid and macula. The fluid interferes with the retina's function and causes your central vision to blur. In addition, what you see when you look straight ahead becomes wavy or crooked, and blank spots block out part of your field of vision.
• Vision loss caused by fluid buildup in the back of the eye. Another type of wet macular degeneration, called retinal pigment epithelial detachment, occurs when fluid leaks from the choroid and collects between the choroid and a thin cell layer called the retinal pigment epithelium (RPE). Abnormal choroidal blood vessel growth is usually not seen when the RPE is detached. Instead, fluid beneath the RPE causes what looks like a blister or a bump under the macula.

                                        

Symptoms

Wet macular degeneration signs and symptoms typically appear and progress rapidly. Signs and symptoms may include:

• Visual distortions, such as straight lines appearing wavy or crooked, a doorway or street sign looking lopsided, or objects appearing smaller or farther away than they really are
• Decreased central vision
• Decreased intensity or brightness of colors
• Well-defined blurry spot or blind spot in your field of vision
• Rapid worsening
• Hallucinations of geometric shapes, animals or people, in cases of advanced macular degeneration

Diagnosis

Regular eye exams are the key to early detection of macular degeneration since symptoms may or may not be present in people who have the disease. Early drusen can be seen in an eye exam before symptoms develop, so you should visit your eye care professional regularly.

Risk Factors

While there are no known causes of macular degeneration, many studies have been performed which illustrate factors that may put you at risk for the disease. There are risk factors you can't control, such as age and genetics, and risk factors that you can control, such as smoking and poor nutrition.

Risk Factors You Can't Control

-Age
-Race (Caucasians are at greater risk)
-Genetics
-Light eye color

Risk Factors You Can Control

-Smoking
-High blood pressure
-High cholesterol
-Poor nutrition
-Unprotected exposure to sunlight
-Obesity
-Sedentary lifestyle

An unhealthy lifestyle, which may include smoking, poor nutrition or limited exercise, could contribute to your risk of developing macular degeneration. As a result, many risk factors are within your control to reduce your chance of getting the disease and to promote better health.

What You Can Do to Reduce Risk:
You can lessen the risk of developing macular degeneration by reducing risk factors within your control, such as smoking and high blood pressure. You are never too young to reduce your risk for disease, so, no matter what your age, you can incorporate the following guidelines into your life.

-Quit smoking
-Control high blood pressure
-Control cholesterol level
-Control cardiovascular disease
-Improve nutrition
-Wear 100% UV protective sunglasses
-Maintain ideal body weight
-Exercise regularly

By following these guidelines, you not only may reduce your risk of developing macular degeneration, but you may also be able to stabilize or slow the effects of vision loss if you have already been diagnosed with the disease.

Early Detection:
People under 50 should have an eye exam every three to five years. People with a family history of eye conditions or those with a medical condition associated with eye disease, such as diabetes, should have their eyes tested every year, particularly if they are over 65. If you notice changes in vision -- vision becomes blurry, for example -- visit your eye doctor immediately.
 
normal amsler grid

distortion of the normal pattern
caused by wet macular degeneration

Treatments

Once dry AMD reaches the advanced stage, no form of treatment can prevent vision loss. However, treatment can delay and possibly prevent intermediate AMD from progressing to the advanced stage, in which vision loss occurs. The National Eye Institute's Age-Related Eye Disease Study (AREDS) found that taking a specific high-dose formulation of antioxidants and zinc significantly reduces the risk of advanced AMD and its associated vision loss. Slowing AMD's progression from the intermediate stage to the advanced stage will save the vision of many people.

Frequently Asked Questions

-What is the dosage of the AREDS formulation?

The specific daily amounts of antioxidants and zinc used by the study researchers were 500 milligrams of vitamin C, 400 International Units of vitamin E, 15 milligrams of beta-carotene (often labeled as equivalent to 25,000 International Units of vitamin A), 80 milligrams of zinc as zinc oxide, and two milligrams of copper as cupric oxide. Copper was added to the AREDS formulation containing zinc to prevent copper deficiency anemia, a condition associated with high levels of zinc intake.

-Who should take the AREDS formulation?

People who are at high risk for developing advanced AMD should consider taking the formulation. You are at high risk for developing advanced AMD if you have either:
1. Intermediate AMD in one or both eyes. or 2. Advanced AMD (dry or wet) in one eye but not the other eye.
Your ophthalmologist can tell you if you have AMD, its stage, and your risk for developing the advanced form. The AREDS formulation is not a cure for AMD. It will not restore vision already lost from the disease. However, it may delay the onset of advanced AMD. It may help people who are at high risk for developing advanced AMD keep their vision.

-Can people with early stage AMD take the AREDS formulation to help prevent the disease from progressing to the intermediate stage?

There is no apparent need for those diagnosed with early stage AMD to take the AREDS formulation. The study did not find that the formulation provided a benefit to those with early stage AMD. If you have early stage AMD, a comprehensive dilated eye exam every year can help determine if the disease is progressing. If early stage AMD progresses to the intermediate stage, discuss taking the formulation with your doctor.

-Can diet alone provide the same high levels of antioxidants and zinc as the AREDS formulation?

No. The high levels of vitamins and minerals are difficult to achieve from diet alone. However, previous studies have suggested that people who have diets rich in green leafy vegetables have a lower risk of developing AMD.

-Can a daily multivitamin alone provide the same high levels of antioxidants and zinc as the AREDS formulation?

No. The formulation's levels of antioxidants and zinc are considerably higher than the amounts in any daily multivitamin.
If you are already taking daily multivitamins and your doctor suggests you take the high-dose AREDS formulation, be sure to review all your vitamin supplements with your doctor before you begin. Because multivitamins contain many important vitamins not found in the AREDS formulation, you may want to take a multivitamin along with the AREDS formulation. For example, people with osteoporosis need to be particularly concerned about taking vitamin D, which is not in the AREDS formulation.

-How is wet AMD treated?

There are a number of treatments for wet AMD: laser surgery, photodynamic therapy, and injected medications are most often used. No treatment is a cure for wet AMD. Each treatment may slow the rate of vision decline, stop further vision loss, or even improve the vision in some select cases. The disease and loss of vision may progress despite treatment.

•Laser surgery.
This procedure uses a laser to destroy the fragile, leaky blood vessels. A high energy beam of light is aimed directly onto the new blood vessels and destroys them, preventing further loss of vision. However, laser treatment also may destroy some surrounding healthy tissue and some vision. Only a small percentage of people with wet AMD can be treated with laser surgery. Laser surgery is more effective if the leaky blood vessels have developed away from the fovea, the central part of the macula. Laser surgery is performed in a doctor's office or eye clinic.The risk of new blood vessels developing after laser treatment is high. Repeated treatments may be necessary. In some cases, vision loss may progress despite repeated treatments.

•Photodynamic therapy.
A drug called verteporfin is injected into your arm. It travels throughout the body, including the new blood vessels in your eye. The drug tends to "stick" to the surface of new blood vessels. Next, a light is shined into your eye for about 90 seconds. The light activates the drug. The activated drug destroys the new blood vessels and leads to a slower rate of vision decline. Unlike laser surgery, this drug does not destroy surrounding healthy tissue. Because the drug is activated by light, you must avoid exposing your skin or eyes to direct sunlight or bright indoor light for five days after treatment. Photodynamic therapy is relatively painless. It takes about 20 minutes and can be performed in a doctor's office.Photodynamic therapy slows the rate of vision loss. It does not stop vision loss or restore vision in eyes already damaged by advanced AMD. Treatment results often are temporary. You may need to be treated again.

•Injectable medications.
There are a number of medications available that can be injected into the eye to directly treat the abnormal blood vessels that arise in wet macular degeneration. This is usually done through a series of injections spaced apart by weeks or months. The medications work by interrupting the cellular signals that lead to abnormal blood vessel growth in the retina.


How the medication is injected: