Ocular Disease
What is age-related macular degeneration?

This is a common ocular disease associated with aging that gradually destroys sharp, central vision. The retina is the very thin tissue that lines the back of the eye and contains the light-sensing cells that send visual signals to the brain. Sharp, clear, 'straight ahead' vision is processed by the macula, which is the central part of the retina. When the macula becomes damaged through ocular disease, many daily activities such as driving and reading become increasingly difficult.

Are there effective treatments for macular degeneration?

If dry age-related macular degeneration (AMD) reaches the advanced stages, there is no current treatment to prevent vision loss. However, a specific high-dose formula of antioxidants and zinc may delay or prevent intermediate AMD from progressing to the advanced stage.

The wet form of the disease can be treated with Lucentis, Macugen, photodynamic therapy, and laser photocoagulation.

  • Lucentis (ranibizumab injection) is an antibody fragment that binds to and inhibits the biologic activity of human vascular endothelial growth factor A (VEGF-A), a protein that is believed to play a critical role in the formation of new abnormal leaky blood vessels, which can damage the area of the eye responsible for central vision. Lucentis is injected into the vitreous portion of the eye (the clear jelly-like substance that fills the eye from the lens back to the retina). Due to the fact that the production of VEGF-A is ongoing, routine administration of this drug is required. In clinical trails, the treatment prevented further vision loss in most patients and improved the vision of some.
  • Macugen (pegaptanib sodium injection) works by blocking vascular endothelial growth factor (VEGF), a protein that promotes blood vessel growth. According to the data collected during the clinical trials, patients receiving Macugen were less likely to progress to legal blindness and experience severe vision loss. Macugen is injected into the vitreous portion of the eye (the clear jelly-like substance that fills the eye from the lens back to the retina). Routine adminitration of Macugen is required due to the fact that the production of VEGF is ongoing.
  • Photodynamic therapy works by injecting a light-sensitive drug called Visudyne (verteporfin) into the patient's bloodstream. The drug circulates throughout the blood vessels, including the abnormal vessels growing beneath the eye's retina. Once the drug has had time to permeate the tiny vessels beneath the retina, the light of a low-intensity laser is shined into the eye. The Visudyne absorbs the light, destroying the abnormal or leaky vessels. Photodynamic therapy has an advantage over photocoagulation because less heat is required from the laser, meaning that healthy tissues around the site of the procedure receive less "collateral damage." One limitation of photodynamic therapy is that it treats only the symptoms of wet macular degeneration. New vessels will continue to grow, and the procedure will have to be repeated. Other light-sensitive drugs are in various stages of evaluation. Researchers are also studying the use of verteporfin in combination with other types of therapies.
  • Photocoagulation requires the eye doctor to focus a high-energy laser onto the abnormal blood vessels in the macular region. The laser heats and destroys the abnormal blood vessels and prevents them from leaking blood and fluid, which can help to prevent or slow down further damage; however, it can scar parts of the macula resulting in some central vision loss. There can be a recurrence of blood vessel leaking and repeating photocoagulation treatment may not always be possible. The treatment is not available to patients when the abnormal blood vessels are located in the center of the macula (called the fovea), therefore, only a small percentage of patients are candidates for this procedure.

If vision loss is permanent, low-vision aids exist that can help improve the quality of life.

How many people suffer from age-related macular degeneration ?

Age-related macular degeneration (AMD) is a major cause of visual impairment in the United States. Approximately 1.8 million Americans age 40 and older have advanced AMD, and another 7.3 million people with intermediate AMD are at substantial risk for vision loss. The government estimates that by 2020 there will be 2.9 million people with advanced AMD.

What are wet and dry macular degeneration?

There are two forms of age-related macular degeneration (AMD): dry and wet. It is possible for a person to suffer from both forms and AMD can affect one or both eyes. The disease can also progress slowly or rapidly. Dry AMD may advance and cause loss of vision without turning into the wet form of the disease. However, it is also possible for early-stage dry AMD to suddenly change into the wet form of the disease.

Dry macular degeneration is the most common type of macular degeneration, affecting approximately 90 percent of people who suffer from the disease. Yellow deposits called "drusen" form under the retina between the retinal pigmented epithelium (RPE) and Bruch's membrane, which supports the retina. Drusen deposits are "debris" associated with compromised cell metabolism in the RPE and are often the first sign of macular degeneration. Eventually, there is a deterioration of the macular regions associated with the drusen deposits resulting in a spotty loss of "straight ahead" vision.

Wet macular degeneration occurs when abnormal blood vessels grow behind the macula. These vessels are very fragile and can leak fluid and blood, resulting in scarring of the macula and the potential for rapid, severe damage. There is a breakdown in Bruch's membrane, which usually occurs near drusen deposits. This is where the new blood vessel growth occurs (neovascularization). "Straight ahead" vision can become distorted or lost entirely in a short period of time, sometimes within days. Wet macular degeneration accounts for approximately 10 percent of the cases, however it results in 90 percent of the cases of legal blindness. All wet AMD is considered advanced.

Do wet and dry macular degeneration have early, intermediate and advanced forms?

All wet age-related macular degeneration (AMD) is considered advanced; however, the dry form of AMD has three stages:

  • Early Dry AMD - patients have several small drusen or a few medium-sized drusen. There is no vision loss or symptoms at this stage.
     
  • Intermediate Dry AMD - patients have many medium-sized drusen or one or more large drusen. Some people may need more light for tasks such as reading. A blurry spot may appear in the center of the visual field.
     
  • Advanced Dry AMD - patients exhibit a large number of drusen deposits and a breakdown of the light-sensitive cells (photoreceptors) and supporting tissue in the retina. A large blurry spot occurs in the center of the visual field and can become larger and darker, eventually causing a complete loss of central vision.

How is macular degeneration diagnosed?

An eye care professional will perform a dilated eye exam, visual acuity test, and view the back of the eye using a procedure called fundoscopy to help diagnose age-related macular degeneration (AMD). If wet AMD is suspected fluorescein angiography may also be performed

What new research is being done to find a cure for macular degeneration?

Ongoing research continues with studies exploring environmental, genetic, and dietary factors that may contribute to AMD. New treatment strategies are also being explored, including retinal cell transplants, drugs that will prevent or slow down the progress of the disease, radiation therapy, gene therapies, a computer chip implanted in the retina that may help simulate vision and agents that will prevent the growth of new blood vessels under the macula.

Is macular degeneration hereditary?

There are several different types of macular disease. The majority of the conditions that affect individuals under 50 years of age are believed to be hereditary and, in many cases, the genes involved have been identified. These conditions are commonly referred to as macular dystrophies.

Age-related macular degeneration (AMD) usually affects individuals older than 50 years of age, and scientific evidence shows that genes may play a role in the development of nearly three out of four cases of this devastating eye disease.

Scientists have also identified two genes, called Factor H and Factor B, which are strongly associated with a person's risk for developing AMD. The Factor H and Factor B genes are responsible for proteins that help regulate inflammation in the part of the immune system that attacks diseased and damaged cells.  According to research at Columbia University, 74 percent of AMD patients carry certain variants in one or both of these genes that significantly increase their risk of this disease.

Researchers have also identified a gene on chromosome 10, called PLEKHA1, which is also associated with a personís risk of developing AMD. PLEKHA1, like Factors H and B, appears to be involved in the cellular processes related to inflammation.

A variation of a gene called LOC387715 increases the risk of developing AMD, and the risk increases dramatically if a person also smokes.

For the most part, the identities of other genes are unknown, but there are several gene candidates that are being studied to determine their role in AMD. There is also evidence that other factors, such as sunlight exposure, diet and cigarette smoking may play a role in the development of AMD.

Can diet prevent macular degeneration?

Some limited studies appear to indicate that eating a diet high in antioxidants may reduce the risk of developing age-related macular degeneration. More research is needed before definitive recommendations can be made concerning diet and its role in macular degeneration. Fruits and vegetables, especially those high in lutein and zeaxanthin, appear to provide the best protection. Lutein and zeaxanthin are also the primary pigments in the macula.

Lutein can be found in spinach, collard greens, kale, broccoli, papaya, oranges, kiwi, mango, green beans, peaches, sweet potatoes, lima beans, squash, red grapes, and green bell pepper.

Zeaxanthin can be found in yellow corn, honeydew melon, squash, oranges, mango, kale, apricots, peaches, and orange bell pepper.

The USDA recommends that adults should be eating three to five servings of vegetables and two to four servings of fruit each day. Plant foods contain phytochemicals (non-nutrient substances), which have been associated with protection not only from macular degeneration, but from cancer, heart disease, diabetes, and a number of other medical conditions. There are many families of phytochemicals; they include indoles, saponins, flavonoids, carotenoids, and others. Lutein and zeaxanthin are both carotenoids. How all of these phytochemicals work together to provide health benefits is not currently known. The good news is that you will be healthier and may be decreasing your risk of developing a number of diseases simply by eating a diet rich in fruits and vegetables.

Can vitamin supplements help treat macular degeneration?

The National Eye Instituteís Age-Related Eye Disease Study (AREDS) found that taking a specific high dose formula of antioxidants and zinc (500 milligrams of vitamin C, 400 International Units of vitamin E, 15 milligrams of beta-carotene, 80 milligrams of zinc as zinc oxide, and two milligrams of copper as cupric oxide) may delay or prevent intermediate AMD from progressing to the advanced stage. There is no evidence, however, that the AREDS formula provided any benefit to people with early stage AMD. Patients with intermediate AMD in one or both eyes or advanced AMD (dry or wet) in one eye but not the other eye should consider taking the formula. You should always talk with your physician before taking any supplements because the formula may be contraindicated due to other medical conditions that you have or medications that you are taking.

Can you get macular degeneration in one eye or does it usually happen in both?

You can get macular degeneration in one eye. However, as the disease progresses, both eyes may become affected.

Can younger people get macular degeneration?

Yes. Early onset macular degeneration (birth to age 7) is a genetic disease. It is called Best disease or vitelliform macular degeneration. Middle onset macular degeneration (age 5 to 20) is also a genetic disorder. This is commonly called Stargardt's disease, fundus flavimaculatus, or macular dystrophy. Finally, people in their thirties or forties can develop a form of the disease that is also inherited. It may be called Sorsby's dystrophy, Behr's dystrophy, Doyne's dystrophy, or honeycomb dystrophy. Finally, myopic macular degeneration can occur in people who are severely near-sighted due to extreme elongation of the eyeball. This condition can result in tears in the macula and bleeding beneath the retina.

Can visual hallucinations occur in people with macular degeneration?

Yes, the condition is called Charles Bonnet Syndrome. In patients who have eye diseases that prevent the normal nerve impulses from reaching the brain, there is speculation that spontaneous nerve activity may be generated by the brain, causing the visual hallucinations. The syndrome appears to be more common in women than men and it is more likely to occur if both eyes are affected by disease. The hallucinations are complex and fully formed images. They are most frequently of animals, people, faces, or scenery. Patients know that the hallucinations are not real. They are not associated with any other sensory hallucinations (such as experiencing sounds or odors), nor are they associated with delusions. The hallucinations may last for seconds or for most of the day. They tend to disappear when people close their eyes. The syndrome may be experienced for a period ranging from days to years. For most people with macular degeneration, the condition is managed by educating the patient and their family and reassuring them that they are not "going insane" or suffering from a psychotic disorder.