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Macular Degeneration

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Forms of Macular Degeneration

Macular Degeneration and Age-Related Macular Degeneration occurs in two main forms: a “dry” or atrophic type and a “wet” or exudative type. Everyone with macular degeneration initially has the dry form and every person with macular degeneration develops the disease in both eyes, however, one eye can worsen more quickly than the other. The dry form of AMD is NOT one disease; there are four major groups of dry AMD. The first three are classified by the size of the small yellow spots (called drusen) that develop in the layer of cells underneath the retina. Drusen come in three sizes: small, medium and large. Patients with small drusen have an excellent chance of keeping good vision during their lifetime. Patients with medium or large drusen have a much higher chance of developing the wet form of macular degeneration, especially if their drusen are associated with small clumps of brown pigment. Patients with medium or large drusen are considered to have “HIGH-RISK” dry AMD. The fourth type of dry macular degeneration is called geographic atrophy, in which the cells underneath the retina slowly wither away. Geographic atrophy only rarely changes into wet macular degeneration, however, it can cause a person to become legally blind if the disease affects the cells underneath the very center of the macula.

Preventive Measures for Macular Degeneration

Treatment for dry macular degeneration depends upon the type of disease present in a patient. All patients with dry macular degeneration should have a coating on the lenses of their eyeglasses to block the ultraviolet rays from the sun. Sunglasses are helpful when outdoors. A daily multivitamin with antioxidants, lutein, zeaxanthin, and zinc may slow the progression of high-risk dry AMD and wet AMD. We do not recommend taking more than 80 mg of zinc per day because this may be harmful to the retina and other organs.

Diagnostics for Macular Degeneration

Although only 10% of patients with AMD will develop the wet type of degeneration, 90% of the patients with severe visual impairment have this form of the disease. In wet AMD, fluid builds up under the retina. Abnormal new blood vessels that grow like tiny weeds under the retina cause this fluid. The fluid can be seen during a retinal examination and documented with a noninvasive test called Ocular Coherence Tomography (OCT). The abnormal blood vessels and the leakage they cause are visualized using a safe intravenous dye test called a fluorescein angiogram. Without treatment, the blood vessels will eventually form a scar and lead to permanent loss of the central vision.

Treatments for Macular Degeneration

A retinal tear can occur due to aging or an eye injury. Similar to retinal detachment, a tear in the retina can cause shadows in vision or flashes. If left untreated, a retinal tear can lead to retinal detachment. Retinal tears often require treatment–but not always.

Some patients with high-risk dry AMD may be eligible for a new laser treatment that can cause the medium and large drusen to disappear within 6 months. Recently the laser treatment has proven to have a significantly beneficial effect on vision in two different well-designed studies. It has yet to be determined from the studies whether the laser treatment will reduce the risk of a patient getting the wet form of AMD; however, this information should be available soon. The new laser treatment for high-risk dry AMD is painless, takes less than 5 minutes and is performed in the office. Approximately 20 very mild laser spots are placed in a semicircular grid pattern around the edge of the macula. Most patients do not even notice the laser spots after treatment; if they are noticeable, the spots usually fade away within 10 days. If both eyes require treatment for the laser, they are treated about a week apart. The patient is asked to return for an exam and fluorescein pictures at 3 months and 6 months after the treatment. If the drusen have not regressed sufficiently after 6 months, another laser treatment may be repeated on the opposite side of the macula.

Every patient with dry macular degeneration is given a special chart with a checkerboard grid pattern called an Amsler Grid. The Amsler Grid that your Retina Specialist gave you has the instructions printed on the back. It is crucial for a patient with macular degeneration to look at his/her grid every day. The proper way to look at the grid is to hold it at a reading distance (with your reading glasses on) and cover one eye at a time. While looking at the round dot in the center, you’re verifying that all the lines appear straight. Some patients with dry macular degeneration may have a few wavy lines on the Amsler Grid; as long as the appearance of the grid does not change from day to day, there is no cause for concern. However, if the lines suddenly become more distorted or lines that were previously straight become wavy, then call the office IMMEDIATELY. We will make every effort to see you in the office within 24 hours. It is very important to understand any sudden noticeable change in the appearance of the grid almost always means there is a problem in the macula and we consider it to be an emergency.

Historically, the first widely used therapy for wet macular degeneration was thermal laser treatment, which has been performed for about 40 years. Because the laser energy is converted to heat (hence the name “thermal”), the major side effect of the laser treatment is a permanent dark or gray scar in the central area of vision. The rationale behind thermal laser treatment was to intervene as soon as possible after the new blood vessels form so the laser scar would be as small as possible. In the vast majority of patients, the vision did not improve or got worse after thermal laser treatment. A series of major studies performed in the 1980s and 1990’s called the Macular Photocoagulation Studies concluded the thermal laser treatment was beneficial in slowing down the anatomical progression of the wet macular degeneration and was better than the natural history, but again, the vast majority of patients almost inevitably continued to lose vision. Currently, thermal laser treatment is reserved for a very small percentage of patients with wet macular degeneration. Usually, it is used when the new blood vessels are well outside the center of the macula. Patients treated with the thermal laser for wet AMD have to be followed by a retinal specialist very carefully because the blood vessels can reappear almost two-thirds of the time and may need additional laser treatment.

Photodynamic Therapy (PDT) is a new laser treatment for wet macular degeneration that was approved by the Food and Drug Administration in 2000. This is a treatment for active wet macular degeneration. PDT is performed in the office by infusing an intravenous dye called Visudyne into a vein in the forearm for about 15 minutes. The dye collects in the abnormal new blood vessels growing under the macula. About 5 minutes after the dye has been given, a non-thermal (“cold”) laser light is focused onto the macula. The light creates a chemical reaction with the dye that causes the new blood vessels to clot. The most important advantage of Photodynamic Therapy is the blood vessels can be treated without damaging the retina since the laser does not produce heat. As a precaution, patients are asked to avoid direct sunlight for 48 hours after the treatment. Since the dye is activated by infrared light, which is found in sunlight, a person with the dye in his/her system can get a very severe sunburn until the Visudyne is cleared from the body. As with traditional laser treatment, patients must be monitored carefully following Photodynamic Therapy since the blood vessels often start to grow again and often require additional photodynamic laser treatment. The results of PDT as a treatment for wet AMD were initially promising but are now considered disappointing. It is most useful in only about 25% of patients with wet AMD and even then, only 6% of eyes improve 3 or more lines of vision after treatment. PDT may have a role in very few patients with wet AMD and current research is concentrating on the use of PDT in combination with other treatment methods.

At this time, the unquestioned gold standard treatment for wet AMD is anti-vascular endothelial growth factor (VEGF) therapy, given as a series of injections into the vitreous cavity. VEGF is a family of 6 proteins produced all over the body, including in the eye that is critically important in the development of both normal and abnormal new blood vessels. In wet AMD, VEGF is produced in abnormally high amounts and leads to the formation of the abnormal new blood vessels that arise from the choroidal layer behind the retina. The new blood vessels are very leaky. VEGF also increases the leakage of fluid from these blood vessels into space underneath the retina and into the retina itself. Because the macula then looks “wet” when a retina specialist is examining the eye this is the derivation of the name: wet macular degeneration. The abnormal blood vessels are fragile and bleed easily resulting in hemorrhage in the macula in some patients with wet AMD.

All anti-VEGF treatments given today are administered as an injection into the vitreous cavity, which is a procedure performed in the office. The surface of the eye is numbed with drops and then an anesthetic injection of lidocaine is given under the conjunctiva (the “skin” covering the white part of the eye). The eye is then thoroughly cleaned and sterilized with betadine and antibiotic drops. The anti-VEGF medication is injected through the anesthetized area into the vitreous cavity using a very tiny needle. The procedure itself is painless and straightforward. However, it is considered an invasive procedure because we are entering the eye itself and there is a rare chance of complications such as cataract, retinal detachment, bleeding or infection. These complications occur in less than one thousand injections. Occasionally, the volume of medication injected temporarily interrupts the circulation to the eye and it might be necessary for the surgeon to remove some fluid from the front of the eye to restore the normal circulation. All patients receiving an injection are asked to take antibiotic drops for four days after the injection to lessen the chance of infection.

The most common question patients ask about any of the anti-VEGF agents is “when does the treatment stop”? The answer, like many things in medicine, is “it depends”. Some retina specialists will treat patients indefinitely because the clinical trials of these medications did just that. Some will treat until the lesion becomes inactive and then observe indefinitely for signs of recurrence. Some will treat until the lesion becomes inactive and then try to extend the time in-between injections. Others will try a combination of treatments – an anti-VEGF drug with a steroid injection or an anti-VEGF drug with PDT laser or all three. Still, others will start with Lucentis or Avastin until the lesion is dry and then perform “maintenance injections” with Macugen.

In May 2005, Dr. Phil Rosenfeld of the Bascom Palmer Eye Institute reported the use of Avastin injections in the eye of a patient with wet macular degeneration. Avastin is an antibody against VEGF that was originally approved for intravenous use in patients with metastatic colon cancer. The reason we are allowed to treat patients with Avastin is a special circumstance referred to as “Off-Label”, in which a physician can use a drug approved for one disease in an unrelated disease if he believes it has the potential to benefit patients. Since 2005, the use of Avastin has become commonplace all over the world and is accepted by the retina specialist community as a standard of care. There are several clinical studies underway to determine Avastin’s effectiveness and safety, however, the results will not be known for several years. Avastin is most commonly given every 6 weeks, though treatment can vary according to the condition of the eye. Additionally, one of Avastin’s advantages is its low cost per dose (approximately $75) compared to Lucentis (approximately$2,500) and Macugen (approximately $1,000).

The FDA approved Lucentis for the treatment of wet AMD in July 2006. Lucentis is a very close relative of the Avastin molecule and is also an antibody to VEGF. According to the results of the ANCHOR and MARINA trials, Lucentis improved the vision 3 or more lines in about 40% of eyes and stabilized the vision by 95%. In terms of scientifically documented results, Lucentis is the best available drug currently approved for wet AMD. Although there has been some concern about potential systemic side effects including hypertension and stroke (for both Lucentis and Avastin), it is unclear at this point if these concerns are significant despite the hundreds of thousands of injections given worldwide. Lucentis is given every 4 to 8 weeks depending on the condition of the eye and the judgment of the retina specialist.

Obviously, at this point in time, there are as many different approaches to treating wet AMD as there are retina specialists. At The Eye Institute, we individualize the treatment to best fit the patient and one doctor will often employ different approaches depending upon the situation. Your physician may even suggest switching medications if the circumstances warrant it. Since there are so many treatment options, it is imperative for you to be well informed. Our Retina Specialists will carefully review your choices and, working together, will devise a treatment plan that will best serve your needs.

Ongoing research investigating the causes and treatment of AMD remains one of the major efforts of the ophthalmology community. Dr. Kirsch is the Principal Investigator for the evaluation of two new potential medications for wet AMD. The results of the studies should be available in the near future. The Eye Institute of West Florida is committed to providing our patients with every opportunity to benefit from the most advanced and current treatments available and will continue participating in clinical research studies in the future.

Leonard Kirsch, MD and Richard Hairston, MD were the first Retina Specialists in the Tampa Bay area to offer these new treatment options for patients with wet macular degeneration.

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