Treatment of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a chronic eye condition that affects people age 50 and older. When a person has macular degeneration, the macula begins to deteriorate, causing symptoms that range from blurred or slightly distorted central vision to a blind spot in the center of the visual field. Macular degeneration is categorized into stages: dry disease and wet disease. Wet disease occurs when abnormal blood vessels form as a complication of the dry disease and cause rapid vision loss.

Ophthalmologists collaborate with colleagues in different specialties to design a macular degeneration treatment plan to meet each patient's needs. Their overall aim is to improve quality of life for patients with macular degeneration by preserving as much eyesight as possible, and preventing further deterioration of vision.

Diagnosis

People with macular degeneration may notice either a rapid onset of symptoms, slight symptoms that progress gradually, or no symptoms at all. Doctors may decide to test for the disease based on family history and symptoms the patient is experiencing. A thorough eye examination is performed by the doctor to identify any abnormalities in the back of the eye, in a portion of the retina called the macula.


Eye exam

During the eye exam, the doctor looks for abnormalities in the macula, such as yellow deposits called drusen. In addition, the appearance of the macula is important to sharp central vision. If the pigmentation is mottled or uneven, instead of its normal even reddish color, macular degeneration may be the cause.



Amsler grid test

As a part of the eye examination, the doctor may evaluate vision using a printed grid. If macular degeneration is present, the lines of the grid may seem faded, broken or distorted. By noting where the distortion occurs (usually near the center of the grid), the doctor can better determine the location and extent of macular damage.




Fluorescein angiography

After diagnosis, the doctor may perform a fluorescein angiography test to determine the extent of damage from macular degeneration. First, the doctor injects fluorescein dye into a vein in the patient's arm. As the dye circulates through the bloodstream and eventually to the eye, a camera takes flash photographs of the eye every few seconds for several minutes. The photos help identify pigmentation changes, blood circulation patterns and abnormal blood vessels.





Indocyanine green angiography (ICGA)

ICGA is another type of angiography of the eye vessels that sometimes provides additional useful information for the doctor to review. ICG is a dye that lights up when exposed to infrared light. Infrared light is used to take pictures of the back of the eye to visualize retinal blood vessels, and the deeper, harder to see choroidal blood vessels.


Optical coherence tomography (OCT)

OCT is an imaging method that uses ultrasound technology to provide detailed, cross-section images of the retina and its underlying layers. OCT is useful for checking retinal thickness and thinness because it is capable of clearly displaying well-defined tissue boundaries in high resolution. Bright colors are added to the image to highlight specific areas of the retina and to determine how much light they reflect.



Genetic testing

In nearly half of patients with age-related macular degeneration, a gene mutation occurs that is responsible for a protein associated with immune system function called Complement Factor H. This is one of the most important discoveries in macular degeneration to date. Mayo Clinic was the first medical center to have routine testing for this gene available to patients.

Treatment

The goal of macular degeneration treatment is to stop further vision loss. In most cases, damage that has already occurred cannot be reversed, making early detection very important for vision preservation.

Dry Macular Degeneration

No treatment is currently available to reverse dry macular degeneration. This condition normally progresses slowly, and many people who have it can live relatively normal lives, especially if vision is affected only minimally.

Progression of dry macular degeneration can be slowed by taking high doses of the vitamins A, C and E, and the minerals zinc and copper. Patients should discuss these vitamin and mineral supplement treatment options with their primary care doctor. Research is under way to identify other vitamin and mineral combinations that may be viable treatments for dry macular degeneration.

A recent study conducted by the National Eye Institute found that a specific vitamin and mineral supplement formulation reduced the risk of dry macular degeneration from advancing to more severe cases by up to 25 percent for some patients. Another study currently under way is testing the benefits of treatment with lutein, an antioxidant, and omega-3 fatty acids in halting or slowing the progression of dry macular degeneration.

Wet Macular Degeneration

In wet macular degeneration, new abnormal blood vessels behind the retina form rapidly. These vessels begin to leak blood and fluid, causing damage to the macula, the region of the retina responsible for central vision. The doctor prescribes treatment based on the location and extent of the abnormal blood vessels.

Anti-angiogenic therapy (injectable drug treatment)

Injectable drug treatments that directly target the growing blood vessels in patients with wet macular degeneration. After the ophthalmologist numbs the eye with an anesthetic, the drug ranibizumab (Lucentis®) or bevacizumab (Avastin®) is injected into the affected eye. The medicine stops or slows the blood vessels from growing, leaking and bleeding.

The treatment is given every four to six weeks to prevent the blood vessels from causing more vision loss. This therapy causes less damage to the retina than laser treatments. The most common side effect after receiving an injection is redness and scratchiness in the eyeball.

Photocoagulation (laser surgery)

Photocoagulation uses a high-energy laser beam to create small burns in areas of the retina that have abnormal blood vessels. This treatment is used when the abnormal blood vessels are not yet under the area of central vision (fovea). Because it is uncommon for the blood vessels to spare the fovea, only a small number of patients are candidates for the procedure.

The doctor determines who may benefit from the treatment based on the location and appearance of the blood vessels, the amount of blood leakage, and the overall health of the macula. The laser may destroy some surrounding healthy eye tissue and some vision. New blood vessels also may develop after this treatment.

Photodynamic therapy

In this treatment, the drug verteporfin (Visudyne®) is injected into the bloodstream. The drug concentrates in the abnormal blood vessels under the macula. The doctor then focuses cold-laser light at the macula, which activates the drug and leads to the closing off of abnormal vessels without damaging the macula. Photodynamic therapy is commonly performed as a combination therapy with other treatments.

The location of the abnormal blood vessels often determines which treatment is selected. The macula is the central portion of the retina responsible for central vision, and the fovea, responsible for the sharpest vision, is directly in the center of the macula. If the abnormal vessels are located directly under the fovea, hot laser treatment (photocoagulation) would damage the fovea and decrease central vision. In these cases, photodynamic therapy may be an excellent option.

Submacular hemorrhage displacement surgery

Although the procedure is used in rare circumstances, patients with recent vision loss associated with blood under the macula who still have healthy tissue around the fovea may be candidates for this surgery. Vitrectomy surgery is performed in conjunction with injections to dissolve the clot and displace the hemorrhage. After the hemorrhage is moved away from the center of vision, the underlying blood vessel that caused the bleeding can then be treated.