Age Related Macular Degeneration (AMD) is a disease that causes damage to the macula, located in the center of the retina. The macula is responsible for fine vision. Macular degeneration is the leading cause of visual impairment in people 65 years or older, being more common in those with a fair complexion. When the macula does not function correctly, central vision may be blurred, distorted, or darkened. Macular Degeneration affects both distance and close vision, making some activities such as driving or reading difficult if not impossible. Although the condition might reduce central vision, it does not affect peripheral or side vision. For example, a patient may see the outline of a clock, but be unable to tell what time it is. While macular degeneration is most common in people over the age of 60, it may develop earlier. It often runs in families.
Dry Macular Degeneration is the most common form of the disease, occurring in approximately 90% of patients with macular degeneration. Dry AMD results when protein deposits (drusen) develop under the macula. Thinning, or atrophy, of the retina may also occur. Dry AMD tends to progress slowly, with vision often remaining normal. When vision loss does occur, it usually advances slowly due to thinning or atrophy of the macula. Patients may notice a dimming of their vision or difficulty reading fine print.
Wet Macular Degeneration is considerably less common than the dry form of the disease, accounting for approximately 10% of patients with AMD. In the wet type, abnormal blood vessels grow under the retina occurring in areas weakened by drusen or atrophy. These new blood vessels that leak serum and lipid may also bleed. Scar tissue forms over time, causing a permanent dark spot in the center of vision. In Wet AMD, there is often sudden loss of vision.
Macular Degeneration can cause various symptoms, while in its earliest stages may even be asymptomatic. If the disease progresses, blurred or distorted vision is common. A central dark or blind spot can also occur. It is possible for vision to deteriorate in one eye while the other one continues to see well for many years. When both eyes are affected, loss of central vision may be noticed immediately. If experiencing any of these symptoms in either eye, immediately schedule an appointment with an eye doctor.
A thorough eye examination will determine if macular degeneration is present. A simple vision test using a grid resembling graph paper (an Amsler grid) is helpful in detecting vision abnormalities due to retinal disease. Eye drops are usually given to dilate the pupil, giving the doctor a better view of the retina.
To obtain additional information, a test called Fluorescein Angiography may be required during which dye is injected into a vein in the arm. Digital images of the retina are obtained as the dye passes through the eye. The abnormal blood vessels leak the injected dye, becoming detectable to the physician. This test aids in the diagnosis and helps to determine treatment. Optical Coherence Tomography (OCT) is a scanning laser used to image a slice of the retina in cross section. OCT is useful in detecting fluid in the macula and for monitoring improvement following treatment.
Macular Degeneration and Nutrition
The role of nutrition in prevention of Age-Related Macular Degeneration (AMD) has long been of great interest to patients and eye care providers. Antioxidant nutrients that may protect the retina from degenerative and oxidative damage have been studied. Some people with AMD have low levels of the mineral zinc, a substance highly concentrated in the eye, particularly the macula.
The Age-Related Eye Disease Study (AREDS) demonstrates that therapeutic dosages of antioxidants and zinc decrease the progression of macular degeneration. It is recommended that people with at least moderate AMD consider taking supplemental antioxidants plus zinc.
AREDS 2 was designed to learn more about the role of vitamins and minerals in preventing vision loss from AMD. This study ran for five years, monitoring 4,000 patients. Results confirmed the benefits of vitamins and minerals in helping to prevent vision loss from AMD. It is recommended that individuals taking supplements for macular degeneration use the “AREDS 2 formula.”
AREDS 2 recommended daily dosages:
Vitamin C 500 mg
Vitamin E 400 IU
Lutein 10 mg
Zeaxanthin 2 mg
Zinc 80 mg
Copper 2 mg
Eating dark green vegetables and fish lowers the rate of vision loss for patients with AMD. Smoking substantially increases the risk of developing AMD with smokers more likely to lose central vision and become legally blind due to this disease.
AREDS 2 supplements have proven to lower the risk of disease progression by 25% in patients with intermediate AMD. The study showed no benefit to those with early or no AMD. Consultation with a medical doctor is recommended before starting these high-dose supplements to avoid drug interactions or medical complications.
Treatment of Wet AMD
Intravitreal Drug Therapy
Intravitreal Drug Therapy is the preferred technique for treating Wet AMD. A number of medicines have been developed which inhibit growth of the abnormal vessels beneath the retina in Wet AMD. These medications are placed directly into the eye with a fine needle. The procedure, performed in the office, is tolerated well. Most eyes receiving intravitreal injections for new onset Wet AMD will have stable or improved vision. To maintain vision, these injections must be repeated at four to ten week intervals, perhaps for the life of the patient.
Laser Treatment used to treat wet macular degeneration is a brief and painless in-office procedure during which a highly focused beam of light is used to destroy the leaking blood vessels that damage the macula. Although a small, permanent “blind spot” is left at the point of laser contact, the procedure can preserve more overall sight. This treatment is usually recommended when abnormal blood vessels have not yet grown under the center of the macula. Pretreatment with intravitreal drug therapy may help to make laser treatment more successful.
In Wet AMD when the abnormal blood vessels are growing under the central macula, photodynamic therapy may be recommended. Photodynamic Therapy utilizes a medication that is injected into an arm vein. This medicine collects and binds to the abnormal blood vessels beneath the macula. A low power laser beam is then used to activate the medication which closes the abnormal blood vessels and decreases the leakage. This often allows the vision to stabilize, although frequent follow-up visits are required and retreatment may be necessary. PDT is usually combined with intravitreal drug therapy to improve visual outcome and decrease the need for retreatment.
Macular Degeneration and the Future
The development of drugs to treat Wet AMD has revolutionized the treatment for this condition. Research is ongoing to discover longer-acting, more effective drugs. Dry AMD, although slowly progressive, has been more resistant to treatment. Clinical trials continue, in hopes of finding a solution.
When treatment cannot restore vision, there are rehabilitation services and aids to help individuals make the most of their remaining sight. At some point we hope to offer gene modification, stem cell therapy, or bionic eyes to restore vision in eyes that are presently considered permanently blind.