Macular Degeneration

 

What is macular degeneration?
The macula is the central area of the retina where reading vision is located. The retina is the light sensitive inner lining in the back   of  the eye that is like the film in a camera. Anatomically, the macula is located in the straight-ahead position of the eye and is at the center of the retina. If the retina were a target, the macula would be the bull’s eye.

Macular degeneration causes a person’s vision to become blurred, distorted and/or dark in the straight-ahead direction. While macular degeneration rarely causes loss of all vision, it can make daily activities such as reading or driving difficult or impossible.

What causes age-related macular degeneration?
Macular degeneration is almost always seen in older people, although in a few families it may start earlier. The prevalence of macular degeneration increases as the population gets older. There is a definite genetic predisposition as shown by studies comparing identical twins and fraternal twins. Other factors that have an effect on the severity of the disease include high-blood pressure and cigarette smoking. It is now the most common cause of legal blindness in retirement-age people in the United States. There are two main forms of macular degeneration: wet and dry.

What is the difference between wet and dry macular degeneration?
Most people who suffer from macular degeneration have the “dry” form. Dry macular degeneration involves changes in the pigment layer of the retina in the back of the eye and the accumulation of yellow deposits called drusen. More light may be required for reading, and it may take longer to adapt to a darker room. Most people maintain the ability to read and drive, but occasionally dry macular degeneration can cause legal blindness.

Wet macular degeneration accounts for about 10% of all cases. Wet macular degeneration is the more severe form of the disease. People with wet macular degeneration develop abnormal leaking blood vessels and membranes under the macula. The size, location and type of the leaking blood vessels determine the proper treatment of the disease. With wet macular degeneration, vision loss is often rapid and severe. There are two types of wet macular degeneration: classic and occult.

What are the symptoms of wet macular degeneration?
Dry macular degeneration is usually a slow process and is hardly noticeable in its early stages. It is important to detect the transition from dry to wet macular degeneration as soon as possible to get the best effect from vision-saving treatments. While symptoms may vary from person to person, there are several ways to detect macular degeneration. These methods work for both wet and dry macular degeneration but a recent onset or worsening of symptoms suggests wet macular degeneration. Common symptoms include: 1) dark areas or holes in the center of your vision, 2) letters or words begin to look blurry when reading and 3) straight lines appear distorted or wavy. One simple way to check for macular degeneration is to use the Amsler grid on the next page.

Instructions for using the Amsler Grid to test your vision:

1. Under a good light source, put on your reading glasses (if any) and hold the grid about 1 foot from your face.
2. Cover one eye. With the other eye, look directly at the center dot on the grid.
3. Note if any of the straight lines appear wavy or distorted, or if there are dark or blurred sections of the grid.
4. Repeat the procedure with your other eye.
5. If you notice blurry, dark or distorted sections on the grid, contact your eye doctor immediately.

How is macular degeneration diagnosed?
Because the early symptoms of wet macular degeneration usually occur in one eye at a time, the good vision in the other eye may cover-up the symptoms of the eye with wet macular degeneration. Many people don’t realize they have the disease until their visual loss is already severe. However, by using the Amsler grid frequently to test your eyes and by testing each eye separately, you can spot the disease early in its course. Regular eye exams also detect early signs of the disease. If you or your physician suspect macular degeneration, your eye doctor can use a microscope and ophthalmoscope to get a detailed view of your macula. Another method to detect abnormal blood vessels in the retina is a special series of eye photographs, called a fluorescein angiogram (Fig. 1), which are taken as fluorescent dye is injected in a vein of the arm.

Indocyanine green angiography i s a similar test which better demonstrates occult macular degeneration. Optical coherence tomography (Fig. 2) is a laser scan that demonstrates fluid accumulation in wet macular degeneration.

How is wet macular degeneration usually treated?
Anti-Angiogenic Drug Injection
For patients with all forms of wet macular degeneration under the center of vision, anti-angiogenic drug injection is usually the therapy of choice. The FDA has approved Macugen and Lucentis, which are Vascular Endothelial Growth Factor (VEGF) inhibitors, for injection into the eye. A third VEGF inhibitor, Avastin, has been approved by the FDA for injection into veins as a cancer therapy.

A relatively painless technique to inject a small amount of the VEGF inhibitor into the vitreous cavity of the eye has been developed. Whenever it is practical, antibiotic drops are taken 1 day before and after the injection to minimize the risk of infection in the vitreous (endophthalmitis).

Lucentis Injection
Since Lucentis is approved specifically for injection into the eye, and since it is usually more effective than Macugen, most of our patients with wet macular degeneration receive Lucentis injections. The level of proof is high for Lucentis. In many FDA approved studies; 95% of patients maintained vision, 75% had some improvement in vision and 40% had a large improvement in vision.

Lucentis injections are given every 4 weeks. When Lucentis injections were stopped after only 3 injections, 80% of patients required retreatment because the vision, which had initially improved, worsened again. Even after 2 years of monthly treatments, some patients lost vision when the treatment was not continued. Deciding when to stop or extend the interval of Lucentis injections is difficult because there are few scientific guidelines.

Macugen Injection
Macugen was the first successful VEGF inhibitor approved by the FDA for injection into the eye. The treatment was better than other treatments at the time, but there were many failures. Because Lucentis and Avastin are more powerful drugs with better results, the use of Macugen has declined and is rarely used anymore.

Avastin Injections
Prior to the release of Lucentis by the FDA, some doctors tried injecting an anti-cancer drug with anti- VEGF properties into the eye and found that it was helpful for patients with macular degeneration. There have not been comparative studies between Avastin and Lucentis so we don’t really know if it is as effective as Lucentis. There is currently a study being conducted to test its effectiveness.

Since Avastin is approved by the FDA for cancer use in humans, the law allows doctors to use it as they think appropriate. This also includes injection into the eye even though it was not designed for this use. In order to use it in the eye, we need to inform the patient that it is “off-label” and of all the risks associated with “off-label” use. An increased risk of strokes and heart attacks has been noted when it is used intravenously to treat cancer. The exact dose of Avastin, the interval between injections and when to stop can only be guessed at with the current state of knowledge.

Medicare and most insurance companies authorize the use of Lucentis for macular degeneration. In patients with no insurance or high co-pays or deductibles, there can be significant out-of-pocket expenses with the use of Lucentis. Avastin is much cheaper and Medicare usually pays for its use in macular degeneration, but since it is “offlabel” they are not obligated to pay. Many insurance companies do not pay since it is “off-label” even though it is cheaper. We use Avastin for macular degeneration most often in patients who would have large outof- pocket expenses for Lucentis. It is up to you, the patient, to choose which drug you would like to use.

Photodynamic Therapy
A head-tohead trial with Lucentis proved that photodynamic therapy with Visudyne was significantly less effective than Lucentis. Also, approximately 2% of patients have immediate and permanent further visual loss from the treatment. The drug is injected into the patient’s arm and travels through the bloodstream to abnormal vessels under the macula. A cold or non-burning laser is focused on the macula to activate the drug, which then closes or blocks off the abnormal blood vessels under the macula. All skin must be covered on the way home on the day of the treatment to avoid severe sunburn. Patients must avoid sun exposure for 5 days after Visudyne treatment. The usual interval between treatments is 3 months.

A small number of patients who have had successful treatments with Visudyne in the past, and patients who refuse injection into the eye, may still receive this treatment.

Thermal Laser
In select patients, early detection of wet macular degeneration outside of the very center of the macula (an area called the fovea) can be treated with thermal laser surgery. Because this kind of laser works by heating the retina, it is called thermal laser. At the point where the thermal laser contacts the macula, a small permanent blind spot is formed, but this area is much smaller than the “hole” in vision left by not treating the disease. Unfortunately, thermal laser can only be used on a small number of patients, and, of those, about half experience a return of the disease which can lead to visual loss.

Are there any new treatments for wet macular degeneration?
Yes! New therapies are constantly being developed. We are currently involved in a National Multi-center trial called Harbour using high dose Lucentis for new cases of wet AMD.

Surgery: In macular rotation surgery, a large incision of the retina is made to detach the entire retina. The entire retina is then rotated up to 60 degrees to place the macula over the healthy underlying tissue and away from the leaking blood vessels. The eye is then filled with silicone oil to hold the retina in place. A second operation a few months later is required to remove the oil and counter-rotate the eye. Severe complications can occur with this rather extensive surgery.

Macular surgery to implant new pigment cells or stem cells under the center of vision have shown variable results, but are in a very early stage of development.

What if I have a macular hemorrhage?
For small hemorrhages , TPA (Tissue Plasminogen Activator) can be injected into the eye with a small gas bubble to liquefy and massage blood clots out from under the macula. Clots under the macula prevent diagnostic testing and treatment with laser and photodynamic therapy, but the TPA gets small to medium size clots out of the way about 50% of the time. For larger and thicker hemorrhages, vitrectomy surgery with injection of TPA beneath the retina may be necessary.

What about aspirin and other anticoagulant medication?
Taking aspirin and other blood thinning medications is not thought to cause bleeding in wet macular degeneration; however, it probably makes the amount of hemorrhage larger when it occurs. There are no restrictions on blood thinners in dry macular degeneration. In patients with wet macular degeneration the risks and benefits of reducing blood thinning medications should be explored. If there is a good indication for the medication, it should be continued.

Are there any treatments available for dry macular degeneration?
A study by the National Eye Institute showed that a daily dose of antioxidant vitamins A (beta carotene 15 mg), C 500 mg, and E 400 IU plus zinc oxide 80 mg and cupric oxide 2 mg, reduced the risk of dry macular degeneration progressing to wet macular degeneration by 25%. Therefore, taking these supplements is recommended once many or large drusen develop or if wet macular degeneration has already developed in one eye. Commercial preparations with the correct formula include: Ocuvite Preservision and I-Caps AREDS formula.

What if vision is reduced despite the best treatment?
Low vision devices can often greatly improve visual performance in people that are considered legally blind. The two major classes of low vision devices are 1) lens magnification combined with a brighter light and 2) Closed Circuit Television (CCTV) with electronic magnification and image intensification. Reputable providers of low vision devices usually present a selection of options, not just a single, very expensive low vision device. Reputable providers also will allow the devices to be used for a while and to be returned if they are not found to be helpful.

		Dr. Mark E. Hammer Dr. Hammer is a retina and macula specialist with more than 25 years experience in the evaluation and treatment of serious eye disease. Since 1986, Dr. Hammer has been in private practice at Retina Associates of Florida.
		Dr. Ivan J. Suñer Dr. Suñer is a retina and macula specialist with more than 12 years experience in the evaluation and treatment of serious eye disease. Before joining Retina Assoc iates of Florida, he served on the faculty at Bascom Palmer Eye Institute in Miami and Duke University.

Retina Associates of Florida is Tampa Bay’s leading medical group in treatment of retinal disease and has offices located throughout the Tampa Bay area. For more information on Retina Associates of Florida, visit RetinaAssociatesFlorida.com or call 1-800-282-9141.