by Mayo Clinic

Definition

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.

Causes

The exact cause of dry macular degeneration is unknown, but the condition develops as the eye ages. Dry macular degeneration affects the macula — a small area at the center of your retina that is responsible for clear vision, particularly in your direct line of sight. Over time the cells that make up your macula break down.

Risk factors

Factors that may increase your risk of macular degeneration include:

• Increasing age. Your risk of macular degeneration increases as you age. Macular degeneration is most common in people over age 60.
• Having a family history of macular degeneration. If someone in your family had macular degeneration, your odds of developing macular degeneration are higher.
• Being white. Macular degeneration is more common in whites than it is in other races, especially after age 75.
• Being female. Women are more likely than are men to develop macular degeneration.
• Smoking cigarettes. Smoking cigarettes increases your risk of macular degeneration.
• Being obese. Being severely overweight increases the chance that early or intermediate macular degeneration will progress to the more severe form of the disease.
• Eating few fruits and vegetables. A diet that includes few fruits and vegetables may increase the risk of macular degeneration.
• Having high blood pressure. Diseases that affect the circulatory system, such as high blood pressure, may increase the risk of macular degeneration.
• Having high cholesterol. An elevated cholesterol level in your blood is associated with an increased risk of macular degeneration.

Dry macular degeneration symptoms usually develop gradually. You may notice these vision changes:

• 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.

When to see a doctor
See your eye doctor if:

• You notice changes in your central vision
• Your ability to see colors and fine detail becomes impaired

These changes may be the first indication of macular degeneration, particularly if you are older than 50.

Tests and diagnosis

Diagnosing dry macular degeneration
Diagnostic tests for dry macular degeneration may include:

• Testing for defects in your central vision. During a complete eye exam, your eye doctor may use a test called the Amsler grid to test for defects in the center of your vision. If you have macular degeneration, when you look at the grid some of the straight lines may seem faded, broken or distorted.
• Examining the back of your eye. Your eye doctor will examine the back of your eye to look for a mottled appearance that's caused by drusen — yellow deposits that form in people with macular degeneration. To examine the back of your eye, your eye doctor will dilate your eyes using eyedrops and then use a special magnifying lens.
• Creating images of the blood vessels in your eye (angiogram). During an angiogram of your eye, a colored dye is injected into a vein in your arm. The dye travels to the blood vessels in your eye. A special camera is used to take pictures of your eye. The pictures show the dye highlighting the blood vessels in your eye. Your eye doctor uses the information from the angiogram images to determine whether the back of your eye shows blood vessel or retinal abnormalities, such as those that might be associated with wet macular degeneration.
• Optical coherence tomography. This noninvasive imaging test helps identify and display areas of retinal thickening or thinning. Such changes are associated with macular degeneration. It's often used to help monitor the response of the retina to macular degeneration treatments.

Determining the stage of your dry macular degeneration
Dry macular degeneration is categorized in three stages based on the progression of damage in your eye:

• Early stage. Several small drusen or a few medium-sized drusen are detected on the macula in one or both eyes. Generally, there's no vision loss in the earliest stage.
• Intermediate stage. Many medium-sized drusen or one or more large drusen are detected in one or both eyes. At this stage, your central vision may start to blur and you may need extra light for reading or doing detail work.
• Advanced stage. Several large drusen, as well as extensive breakdown of light-sensitive cells in the macula, are detected. This causes a well-defined spot of blurring in your central vision. The blurred area may become larger and more opaque over time.

Treatments and drugs

There's no treatment available to reverse dry macular degeneration. But this doesn't mean you'll eventually lose all of your sight. Dry macular degeneration usually progresses slowly, and many people with the condition are able to live relatively normal, productive lives, especially if only one eye is affected. Your doctor may recommend annual eye exams to see if your condition is progressing.

Increased vitamin intake
Taking a high-dose formulation of antioxidant vitamins and zinc may reduce the progression of dry macular degeneration to vision loss, according to research by the National Eye Institute (NEI). In its research, the NEI used a formulation that included:

• 500 milligrams (mg) of vitamin C
• 400 international units (IU) of vitamin E
• 15 mg of beta carotene (often as vitamin A — up to 25,000 IU)
• 80 mg of zinc (as zinc oxide)
• 2 mg of copper (as cupric oxide)

Ask your doctor whether this formulation may help you reduce your risk of vision loss. Studies found this specific combination of vitamins can't cure severe vision loss, but it may reduce the risk of vision loss in people with intermediate macular degeneration. If you have advanced stage macular degeneration in one eye, this combination of vitamins may reduce the risk that you'll develop vision loss in your other eye. But for people with early-stage dry macular degeneration, there's no evidence that these vitamins provide a benefit.

Tell you doctor if you smoke, since beta carotene supplements have been linked to an increased risk of lung cancer in smokers. Your doctor may recommend an alternative formulation of vitamins for you.

Your doctor may also recommend lifestyle changes to incorporate more of the fruits and vegetables that contain these vitamins into your diet, along with other foods, such as fish, that contain nutrients believed to contribute to eye health. Some people may prefer to make lifestyle changes, rather than take supplements. Others may wish to combine supplements with lifestyle changes. Discuss your options with your doctor.

Surgery to implant a telescopic lens in one eye
For people with advanced macular degeneration in both eyes, one option to improve vision may be surgery to implant a telescopic lens in one eye. The telescopic lens, which looks like a tiny plastic tube, is equipped with lenses that magnify your field of vision. The telescopic lens implant may improve both distance and close-up vision.