Wet macular degeneration

Definition

Age-related macular degeneration is a chronic eye disease in which the part of your eye responsible for central vision — your macula (MAK-u-luh) — gradually deteriorates, causing blurred central vision or a blind spot in the center of your visual field. Macular degeneration tends to affect adults age 50 and older.

Wet macular degeneration occurs when new blood vessels grow and leak fluid underneath the macula, an area of densely packed light-sensitive cells in the central part of the retina. Most cases of wet macular degeneration develop from the dry type of macular degeneration.

Early detection and treatment of wet macular degeneration may help reduce the extent of vision loss and in some instances improve vision.

Symptoms

With wet macular degeneration, the following signs and symptoms may appear and progress rapidly:

• 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
• Abrupt onset
• Rapid worsening
• Seeing nonexistent things (hallucinating), such as unusual patterns, geometric figures, animals or even faces, caused by disrupted communication between the deteriorated macula and the brain

Your vision may falter in one eye, while the other remains fine for years. You may not notice any changes or only mild changes because your good eye compensates for the eye with macular degeneration. Your vision and lifestyle are dramatically affected when this condition develops in both eyes.

When to see a doctor
See your eye doctor — particularly after age 50 — if:

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

One way to monitor your eyes to determine if you may need to visit your eye doctor is to check your vision regularly using an Amsler grid. This simple test may help you detect changes in your sight that you otherwise may not notice.

Here's what you do:

• Hold the grid 14 inches in front of you in good light. Use your corrective spectacles or reading glasses if you normally wear them.
• Cover one eye.
• Look directly at the center dot with your uncovered eye.
• While looking at this dot, determine whether all the lines of the grid appear straight, uninterrupted and with the same contrast.
• Repeat the above steps with your other eye.
• If any part of the grid is missing or looks wavy, blurred or dark, contact your eye doctor immediately.

Amsler grid (PDF file requiring Adobe Reader)

Vision with macular degeneration

Vision with macular degeneration

As macular degeneration develops, clear, normal vision (shown left) becomes impaired by a general haziness. With advanced macular degeneration, a blind spot forms at the center of your visual field (shown right).

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Amsler grid

Amsler grid

Viewing an Amsler grid in the advanced stages of macular degeneration, you may see distorted grid lines or a blank spot near the center of the grid (right).

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Causes

Wet macular degeneration develops when abnormal new blood vessels grow from the choroid — the layer of blood vessels sandwiched between the retina and the outer, firm coat of the eye called the sclera — under and into the macular portion of the retina (a process known as choroidal neovascularization). These abnormal vessels leak fluid or blood, which is why this form of macular degeneration is called "wet." Fluid or blood between the choroid and macula 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.

Eyes with the wet form of macular degeneration almost always show signs of the dry form — yellow fat-like deposits (drusen) and mottled pigmentation of the retina.

The wet form accounts for about 15 percent of all cases, but it's responsible for most of the severe vision loss that people with macular degeneration experience. If you develop wet macular degeneration in one eye, your odds of getting it in the other eye increase greatly.

Much like the dry form of macular degeneration, the wet form may be caused by a breakdown in the eye's waste-removal system. The light-sensitive cells in the retina called cones and rods produce waste. If this waste accumulates, it interrupts the retina's nutrient supply, and retinal tissue deteriorates. Whether this is the mechanism that triggers the growth of abnormal blood vessels is unclear, and it remains the subject of scientific study.

With the wet form of macular degeneration, sight loss is usually severe and rapid, often deteriorating to 20/200 vision or worse, occurring within weeks or months. When vision is 20/200 or worse in both eyes, you're considered legally blind.

Retinal pigment epithelial detachment
Another form of wet macular degeneration, called retinal pigment epithelial detachment, occurs when fluid leaks from the choroid and collects between the choroid and the next-deeper cell layer, the retinal pigment epithelium (RPE). No abnormal choroidal blood vessel growth is apparent when the RPE is detached. Instead, fluid beneath the RPE causes what looks like a blister or a bump under the macula.

Although this kind of macular degeneration causes symptoms similar to those of typical wet macular degeneration, your vision can remain relatively stable for many months or even years before it deteriorates. Eventually, however, RPE detachment tends to evolve to the more common wet form of macular degeneration associated with the development of newly growing abnormal choroidal blood vessels.

Parts of the eye

Parts of the eye

Located at the back of your eye in the center of your retina, a healthy macula allows for normal central vision acuity. The macula is made up of densely packed light-sensitive cells called cones and rods. Cones are responsible for color vision and rods enable you to see shades of gray.

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Wet macular degeneration

Wet macular degeneration

Abnormal blood vessels growing out of the choroid push up the retinal pigment epithelium (RPE). Fluid and blood leaking from these vessels can cause severe vision loss.

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Risk factors

Researchers don't know the exact causes of macular degeneration, but they have identified some contributing factors, including:

• Age. In the United States, macular degeneration is the leading cause of severe vision loss in people age 60 and older.
• Family history of macular degeneration. If someone in your family had macular degeneration, your odds of developing macular degeneration are higher. In recent years, researchers have identified some of the genes associated with macular degeneration. In the future, genetic screening tests may be helpful for assessing early risk of the disease.
• Race. Macular degeneration is more common in whites than it is in other groups, especially after age 75.
• Sex. Women are more likely than men to develop macular degeneration, and because they tend to live longer, women are more likely to experience the effects of severe vision loss from the disease.
• Cigarette smoking. If you smoke, stop. Exposure to cigarette smoke doubles your risk of macular degeneration. Cigarette smoking is the single most preventable cause of macular degeneration.
• Obesity. Being severely overweight increases the chance that early or intermediate macular degeneration will progress to the more severe form of the disease.
• Light-colored eyes. People with light-colored eyes appear to be at greater risk than do those with darker eyes.
• Exposure to sunlight. Although the retina is more sensitive to shorter wavelengths of light, including ultraviolet (UV) light, only a small percentage of ultraviolet light actually reaches the retina. Most ultraviolet light is filtered by the transparent outer surface of your eye (cornea) and the natural crystalline lens in your eye. Some experts believe that long-term exposure to ultraviolet light may increase your risk of developing macular degeneration, but this risk has not been proved and remains controversial.
• Low levels of nutrients. This includes low blood levels of minerals, such as zinc, and of antioxidant vitamins, such as A, C and E. Antioxidants may protect your cells from oxygen damage (oxidation), which may partially be responsible for the effects of aging and for the development of certain diseases such as macular degeneration.
• Cardiovascular diseases. These include high blood pressure, stroke, heart attack and coronary artery disease with chest pain (angina).

Preparing for your appointment

To check for macular degeneration, a dilated eye exam is necessary. Make an appointment with a doctor who specializes in eye care — an optometrist or an ophthalmologist — who can evaluate your condition and perform a complete eye exam.

What you can do
Appointments can be brief. Make the best use of that limited time by preparing beforehand.

• Be aware of any pre-appointment restrictions. When you make the appointment, ask if there's anything you need to do in advance.
• Write down any symptoms you're experiencing, including any that may seem unrelated to your vision problem. For example, it's important to tell your doctor if you've been seeing things you can't explain, particularly shapes, patterns or faces. If you have macular degeneration, such visions are related to macular cell damage and are not, as you may fear, the result of mental illness.
• Make a list of all medications, as well as any vitamins or supplements, that you're taking.
• Ask a family member or friend to accompany you, if possible. Having your pupils dilated for the eye exam will affect your vision for a time afterward. You may need someone else to drive or accompany you after your appointment.

Questions to ask your eye doctor

• What kind of macular degeneration do I have?
• What is the visual acuity in my central vision?
• How advanced is my macular degeneration?
• Will I experience further vision loss?
• Will taking a vitamin or mineral supplement help prevent further vision loss?
• What's the best way to monitor my vision for any changes?
• What low vision aids or adaptive devices might be helpful to me?

Questions your eye doctor may ask

• When did you first notice your vision problem?
• Does the condition affect one or both eyes?
• Do you have trouble seeing things near you, at a distance or both?

Tests and diagnosis

Diagnostic tests for macular degeneration may include:

• An eye examination. One of the things your eye doctor looks for while examining the inside of your eye is the presence of drusen and mottled pigmentation in the macula. The eye examination includes a simple test of your central vision and may include testing with an Amsler grid. If you have macular degeneration, when you look at the grid some of the straight lines may seem faded, broken or distorted. By noting where the break or distortion occurs — usually on or near the center of the grid — your eye doctor can better determine the location and extent of your macular damage.

  Regular screening eye examinations can detect early signs of macular degeneration before the disease leads to vision loss.

• Angiography. To evaluate the extent of the damage from macular degeneration, your eye doctor may use fluorescein angiography. In this procedure, fluorescein dye is injected into a vein in your arm and photographs are taken of the back of the eye as the dye passes through blood vessels in your retina and choroid. Your doctor then uses these photographs to detect changes in macular pigmentation or to identify small macular blood vessels.

  Your doctor may also suggest a similar procedure called indocyanine green angiography. Instead of fluorescein, a dye called indocyanine green is used. This test provides information that complements the findings obtained through fluorescein angiography.

• Optical coherence tomography. This noninvasive imaging test helps identify and display areas of retinal thickening or thinning. Such changes are associated with macular degeneration. This test can also reveal the presence of abnormal fluid in and under the retina or the RPE. It's often used to help monitor the response of the retina to macular degeneration treatments.

Treatments and drugs

Treatment of wet macular degeneration focuses on stopping further progression of the disease.

Wet macular degeneration treatments include:

• Laser therapy (photocoagulation). In this treatment, your doctor uses a high-energy laser beam to destroy abnormal, leaky blood vessels — known as choroidal neovascularizations (CNVs) — under the macula. The procedure is used to prevent further damage to the macula and halt continued vision loss for as long as possible.

  Laser therapy has major limitations as a treatment for wet macular degeneration. It generally isn't used if you have CNV directly under the center of the macula. Also, the more damaged your macula is, the lower the likelihood of success. Because of these restrictions, only a small percentage of people who have wet macular degeneration are good candidates for laser therapy.

  Laser treatment won't replace any dark or gray spots that are already completely and permanently blank. With time, however, you may stop being aware of this spot, especially when you use both eyes. About half of those who seem likely to have a good result eventually need repeat laser surgery. However, repeat laser treatment isn't always an option.

  If you closely monitor your vision and have frequent follow-ups with your doctor, you may retain more sight than if you go untreated.

• Photodynamic therapy (PDT). This therapy is primarily used for treating CNV directly under the fovea. The fovea lies at the center of your macula and in healthy eyes provides your sharpest vision. If conventional hot-laser surgery were used at this location, it could destroy all or part of your central vision. PDT increases your chances of preserving some of that vision. It won't bring back any of the vision you have lost, but it may halt the loss of your vision or at least slow down the rate of vision loss.

  This procedure combines a cold laser and a light-sensitizing drug called verteporfin (Visudyne) that's injected into your bloodstream. The drug concentrates in the CNV under the macula. When your doctor directs cold-laser light at the macula, the drug releases substances that theoretically can close off the abnormal blood vessels without damaging the macula, and the CNV transforms into a thin scar.

  The overlying rods and cones are largely preserved, so there's a better chance that you'll preserve some of your vision with this procedure than if you had hot-laser surgery or no treatment at all. The therapy can be repeated if the CNV doesn't close or if it reopens after initial closure. After the procedure, you'll need to avoid direct sunlight and intensely bright lights until the drug wears off, about five days after treatment.

• Macular translocation surgery. Macular translocation surgery is a procedure used in select circumstances when abnormal blood vessels are located directly under the fovea. To perform the procedure, your surgeon detaches the retina, shifts the fovea away from the CNV and relocates it over healthy tissue. The surgeon can remove the exposed CNV with tiny forceps or use a hot laser to destroy blood vessels without damaging the fovea. This surgery can be successful for preserving vision, and in some instances improving vision, if your vision loss is recent, the extent of CNV is limited and the tissue around the fovea is healthy. This surgery is not widely used.

• Vascular endothelial growth factor antagonists (anti-VEGF medications). These drugs help stop growth (proliferation) of new CNV by blocking the effects of a growth factor these blood vessels need to thrive. These drugs are commonly used and are among the most effective therapies for treating wet macular degeneration.

  Pegaptanib (Macugen), one early anti-VEGF medication, stops the formation of new blood vessels and decreases leakage from existing blood vessels. However, other more recent and more effective anti-VEGF medications have largely replaced Macugen. These include ranibizumab and bevacizumab.

  Both ranibizumab (Lucentis) and bevacizumab (Avastin) — a colon and rectal cancer treatment drug that's closely related to ranibizumab — stop fluid leakage from CNV. In some instances, you may partially recover vision as the blood vessels shrink and the fluid under the retina absorbs, allowing retinal cells to regain some function. Other anti-VEGF medications are currently being studied, but they're not yet available for clinical use.

  Anti-VEGF medications are injected directly into your eye. You may need repeat injections every four weeks to maintain the beneficial effect of the medication. Researchers are investigating whether anti-VEGF medications might prove more effective when used in combination with other therapies, such as PDT or injections of steroid drugs (glucocorticoids). Also being investigated is the optimal timing of the intervals between injections of anti-VEGF medications.

• Implantable optical devices. A miniature telescopic device implanted into the eye may improve visual acuity and quality of life in people with very advanced macular degeneration. The device helps to enlarge objects in the central part of your visual field.

Because research into new treatments for macular degeneration is ongoing, it's a good idea to visit your doctor periodically to see if a new treatment might be available.

Lifestyle and home remedies

Macular degeneration doesn't affect your side (peripheral) vision and usually doesn't cause total blindness. But it can rob you of your central vision — which is important for driving, reading and recognizing people's faces. A low-vision center may be able to assess your visual capabilities and suggest certain optical and household devices that can be helpful for some near-vision tasks. Ask your eye doctor if there are any low-vision centers in your area.

There are ways to cope with impaired vision. Below are a few suggestions:

• Use caution when driving. First, check with your doctor to see if driving is still safe based on your current visual acuity. Even if you can drive, there are certain situations to avoid. For example, don't drive at night, in heavy traffic or in bad weather.
• Seek help traveling. Use public transportation or ask family members to help, especially with night driving.
• Travel with others. Contact your local area agency on aging for a list of vans and shuttles, volunteer driving networks or ride shares.
• Get good glasses. Optimize the vision you have with the right glasses, and keep an extra pair in the car.
• Use magnifiers. Large-print books and magazines can help you read more easily.
• View with large type on the Internet. Look for Web sites that use large-sized type fonts, or change the font size on your display.
• Obtain specialized appliances. Some clocks, radios, telephones and other appliances have extra-large numbers.
• Have proper light in your home. This will help with reading and other activities.
• Remove home hazards. Eliminate throw rugs and other possible tripping hazards in your home.
• Ask friends and family members for help. Tell them about your vision problems so that they can help you perform certain tasks and help you recognize people.
• Don't become socially isolated. A common frustration of people with macular degeneration is the inability to recognize other people and greet them by name. If this happens to you, try asking people you know to greet you and tell you their names when you meet.
• Take advantage of online networks. The Internet is a good source for support groups and resources for people with macular degeneration.

Alternative medicine

Some people have turned to complementary or alternative therapies, such as bilberry, ginkgo and shark cartilage, in the belief that they can help prevent the progression of macular degeneration.

However, there's no conclusive evidence that any of these products are effective for macular degeneration, and some may interact with other medications you're taking. Check with your doctor before taking any dietary or herbal supplement.

Prevention

The following measures may help you avoid macular degeneration:

• Eat foods containing antioxidants. Foods with antioxidants are those rich in vitamins A, C and E. People who eat diets rich in vegetables, particularly leafy green vegetables, may have a lower risk of macular degeneration. The National Eye Institute is currently sponsoring a clinical trial to assess the efficacy of specific antioxidants — lutein, zeaxanthin and omega-3 fatty acids — in lowering the risk of macular degeneration. Lutein and zeaxanthin are found in high concentrations in egg yolks, corn and spinach and other green leafy vegetables. Omega-3 fatty acids are found in high concentrations in fish and certain nuts, such as almonds.
• Stop smoking. Smokers are more likely to develop macular degeneration than are nonsmokers. Ask your doctor for help, if needed, to stop smoking.
• Manage your other diseases. For example, if you have cardiovascular disease or high blood pressure, take your medication and follow your doctor's instructions for controlling the condition.
• Get regular eye exams. Early detection of macular degeneration increases your chances of preventing serious vision loss. If you're older than 40, get an exam every two to four years, and older than 65, every year or two. If you have a family history of macular degeneration, have your eyes examined more frequently.
• Screen your vision regularly. If you've received a diagnosis of early-stage macular degeneration, your doctor may suggest that you regularly monitor your vision at home with an Amsler grid. Doing so may help you to detect subtle changes in your vision at the earliest possible time and seek help promptly.

If you have some vision loss because of macular degeneration, your eye doctor can prescribe optical devices called low-vision aids that will help you see better for close-up work. Or your doctor may refer you to a low-vision specialist. In addition, a wide variety of support services and rehabilitation programs are available that may help you adjust your lifestyle.