As we age, our bodies inevitably exhibit the effects of daily living. The care of the eye and treatment of any malady detected are essential to the preservation, or even improvement, of vision.
By Mike Haskew
Anyone 55 years or older is at an increased risk for developing macular degeneration. According to the National Eye Institute, the disease affects an estimated 1.75 million people in the United States; that number is expected to increase to 3 million by the year 2020 as the U.S. population continues to age. Although it rarely results in total blindness, the disease is often referred to as age-related macular degeneration and is the leading cause of pronounced vision loss among people over the age of 60. According to some experts, as many as 140,000 cases of severe central vision loss occur each year in North America.
“Macular degeneration is fairly common and largely a process of aging and what has happened to the eye over many, many years,” explains Dr. Mark Kapperman, an optometrist practicing in Chattanooga for the last 21 years. “Certainly age is a great factor; the disease is one of those souvenirs of time and the things that happen to our bodies.”
Macular degeneration occurs when the central portion of the retina (macula) – the light-sensing nerve tissue located at the back of the eye – begins to lose its ability to function properly.
There are two primary forms of macular degeneration: dry and wet. Dry macular degeneration occurs when yellow deposits, known as drusen, develop in the macula. Their presence and continuing growth can result in distorted vision or dimming. As the disease advances, it can be characterized by a thinning of the cells within the macula that sense light and lead to the atrophy, or death, of these cells. Blind spots or complete loss of central vision may result when dry macular degeneration is left untreated. In addition, the condition may cause the onset of wet macular degeneration.
Wet macular degeneration affects only about 10 percent of sufferers, but accounts for the majority of significant vision loss in patients. It occurs with formation of abnormal blood vessels beneath the macula. As they grow, these vessels may actually leak blood and fluid, which distorts vision and results in scarring. This typically will further impair vision and can lead to blind spots or the permanent loss of central vision.
“Wet macular degeneration tends to be more blinding,” notes Dr. Charles Kirby, an ophthalmologist with the Chattanooga Eye Institute. “It is also the one that progresses very rapidly, while the dry variant progresses slowly. However, when I say that, it is true that there always tends to be an exception.
“In the wet version, new blood vessels can actually rupture and damage the surrounding tissue,” says Dr. Kirby. “Dry macular degeneration is a different animal; basically, the retina just wears out. Unfortunately, it will inevitably progress with age.”
The primary known risk factors for macular degeneration are heredity, aging and smoking. An individual’s genetic predisposition for developing the disease is also a factor; however, lifestyle-related decisions can affect the onset of macular degeneration. Additionally, quitting smoking, eating a healthy diet and getting plenty of exercise may positively influence overall general health. An annual dilated eye exam is critical to early detection, particularly as an individual gets older.
“Early detection allows whatever can be done to be done,” explains Dr. Kapperman. “Everything is evaluated on a case-by-case basis, and there is no guarantee that catching it early will prevent loss of sight. It just depends on some persons having the milder and slowly progressive type.”
“In macular degeneration, genetics is the biggest component,” says Dr. Richard Breazeale, an ophthalmologist with Southeastern Retina Associates. “Also, if you are a smoker, quitting does decrease the risk of the progression of dry macular degeneration. Pay attention to what you eat and what vitamins you take. Eat green leafy vegetables, which have been shown to decrease the risk of macular degeneration and the progression of the dry variant.”
Dr. Breazeale sites a recent study, the “Age Related Eye Disease Study” (AREDS) conducted by the National Eye Institute, which reveals promising news related to macular degeneration.
“The study asked two questions,” Dr. Breazeale says. “The first was, ‘If you take antioxidants, can you reduce the risk of cataracts?’ The answer was ‘no.’ The second question was, ‘If you take antioxidants, can you reduce the progression of dry macular degeneration?’ The answer was ‘yes.’ If you have macular degeneration with moderate loss of vision in one eye, you can decrease your risk of visual loss in the other eye by 25 percent – and that is a big deal.
“You can take the AREDS formula, which includes beta carotene, vitamins C and E, and zinc and copper,” Dr. Breazeale continues. “The most famous brand of this formula is Ocuvite PreserVision by Bausch & Lomb. We have known that taking antioxidants was beneficial for macular degeneration, but it was not proven until the study.”
Research into the causes of macular degeneration is ongoing, and some significant progress has been made in recent years. According to physicians, the identification of vascular endothelial growth factor (VEGF) as a significant contributor to wet macular degeneration was a step in the right direction. Further, the discovery of antibodies to VEGF has led to new treatment options.
“There was a compound found that was originally approved to treat metastatic colon cancer,” remarks Dr. Kirby, “and it was also found to have the antibody against VEGF. Consequently, there are several compounds that inhibit the growth factor and can actually arrest the growth of the new blood vessels that are present in wet macular degeneration. These are the best treatments we have ever had for the disease.”
In 2005, Eyetech introduced the drug Macugen, which changed the face of macular degeneration treatment, according to Dr. Breazeale. The following year, Genentech began to offer Lucentis, another prescription drug that actually produced even better results, adds Dr. Breazeale.
“With wet macular degeneration, history tells us that patients have a 70 percent chance of severe vision loss within six months of diagnosis,” he says. “With Lucentis, there is a 95 percent chance that won’t happen. Along with that, there is a 40 percent to 45 percent chance that visual acuity will improve by a factor of two, so 20/40 vision would become 20/20; there is a 75 percent chance that a patient’s vision will not decrease another notch.
“In layman’s terms, with Lucentis, for the first time in history there is a 75 percent chance that the vision of macular degeneration patients will remain stable. When Lucentis came along, most people with wet macular degeneration got better rather than worse.”
Treatment for wet macular degeneration varies, depending on its progress upon diagnosis. Along with the introduction of vitamin therapy and drugs that inhibit the growth of abnormal blood vessels, lasers may be used to destroy abnormal blood vessels. A laser treatment named Photodynamic laser therapy involves the injection of a drug into the bloodstream. The drug is absorbed by the abnormal vessels and then a cold laser is used to target the blood vessels and destroy them.
Surgical removal of abnormal blood vessels is also a treatment option. However, in situations where abnormal vessels are located beneath the center of the macula, and the introduction of a laser is deemed unsafe, the abnormal vessels may be treated through retinal translocation surgery. During this procedure, the center of the macula is actually rotated away from the area of abnormal blood vessel growth. When the rotation is completed, a laser is then used to destroy the abnormal vessels.
“There are three classic methods of treating the new vessels growing under the retina,” remarks Dr. Breazeale. “One, we can burn the vessels with the laser. Two, we can use the photodynamic therapy, in which these abnormal vessels leak the light-sensitive agent contained in a dye. When we shine the cold laser on that spot, it activates the dye, causing it to release poisonous free radicals that cause them to stop leaking. However, when number three – Macugen – came along, we pretty much walked away from this.”
For ophthalmologists and the retina specialists to whom they refer cases of macular degeneration, the diagnosis or suspicion of the presence of the disease is often a daily occurrence. Recognizing its symptoms is the first step in treatment. Unfortunately, there is no cure for the disease, and there is no guarantee that it will not recur following successful treatment. Therefore, early detection and vigorous follow-up is important to minimize its impact on quality of life.
“Typically, the primary symptom is a decrease in central vision – dead-straight-ahead vision,” relates Dr. Kirby. “People develop symptoms like metamorphopsia, which means that straight lines become distorted. When looking at straight things, like a telephone pole or the edge of a door, it becomes distorted in some fashion instead of being straight; a portion of it may appear to be bent or missing. Also, a person can develop a dark spot, called a scotoma, in their central vision. Another symptom in some people is vision that gets worse suddenly, over a period of one or two days.”
Dr. Kapperman comments: “Macular degeneration may be detected through a very simple process using an angular grid. A person may be able to self-test for visual distortion. Having one of these (tests) on-hand is a good idea if you suspect macular degeneration or have a strong family history of the disease.” Known as the Amsler Grid, this tool can be obtained from a doctor or printed directly from the Internet.
Delaying the onset of macular degeneration and effectively treating both the wet and dry forms lies in understanding the risk factors, recognizing the symptoms and vigilantly protecting eyesight through annual examinations. Although macular degeneration can be a devastating disease, it can often be managed through treatment.
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