Diagnosis and Treatment on Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a condition of the eye that attacks the macula, the central part of the retina. It affects about 11 million Americans, and is the leading cause of blindness for people over 55.�

Do you suffer from AMD? Do you suspect you might, later in life? Perhaps you have relatives with MD, or are yourself showing some symptoms. If so, it is time to seek help.�

What is AMD, exactly?

The retina is that part of the eye that transfers incoming light to the brain. The macula lets us see the fine details of the image. AMD is not painful, but it blurs the details we need for driving, reading or sewing. It's most common in older people, although its onset may come during middle age. Our risk of developing AMD rises as we age. According to The National Institutes of Health, other risk factors include:

o Smoking

o Obesity

o Race - Whites are much more likely to lose vision from AMD than African-Americans.

o Family history: People with a family history of AMD are at higher risk of getting the disease.

o Gender: Women appear to be at greater risk than men.
There are two types of AMD: wet and dry. This has nothing to do with whether or not you feel sad, or are weeping. If new, fragile blood vessels form under the macula, leaking of blood and fluid may occur, collecting under the macula and forcing it to swell, detaching it from its usual place. Dry AMD is not caused by blood vessels or the leakage of fluid, but rather by the degeneration of light-sensitive cells of the macula itself. As we age, we may notice a blurry spot in the center of the vision field. Eventually, AMD may cause blindness.�

How is AMD diagnosed?�

Doctors find AMD by examining dilated eyes, a visual acuity test (the top row is always "E") and tonometry (defined below).�

Many people have experienced eye dilation, but for those who have not had the privilege, it is a simple procedure. Drops are put in your eyes to widen the pupils. Once the pupils are dilated, the doctor can use a magnifying lens to examine your retina for signs of AMD, perhaps using a tonometer, an instrument that measures the pressure inside the eye. You may request some numbing drops for this procedure.�

Your doctor may do other tests as well. One they may perform is the Amsler grid. You will be asked to stare at a center dot in the middle of a grid pattern. Those who see warped or missing lines around the dot may have AMD. Your doctor is the best person to make the diagnosis, however much your relatives may know. Even if your lines are all there nice and straight, ask the doctor to give you a grid to use in the future. Dry AMD, according to the NIH, can "turn into wet at any time." If dry AMD is allowed to reach the advanced stage, vision loss is inevitable.�

This is not good news for sufferers, but there is hope. For one thing, treating dry AMD may prevent it from progressing to advanced wet AMD. The National Eye Institute funded a study that showed a high-dosage combination of antioxidants and zinc reduced the risk of vision loss significantly.�

Studies at the UCSD School of Medicine and the University of Utah have resulted in the development of a "mouse model" of AMD. Study co-author David Williams, Ph.D., UCSD professor of pharmacology and neurosciences, said the mouse model "now permits the testing of potential therapies for the �dry' version of AMD…in an animal model. The study found that with AMD high levels of "debris" called lipofuscin which accumulates in the retinal cells and causes vision loss. The testing of new therapies will be possible with this "mouse model."�

Treating AMD:

There is no cure, but wet AMD can be treated two ways: by laser surgery and what is called Photodynamic Therapy. Laser surgery destroys the rogue blood vessels that cause vision reduction, but they will probably return, in which case, repeated treatments may be needed. Laser surgery is usually performed outside a hospital, in the doctor's office or an eye clinic. The procedure is simple: you receive an injection of verteporfin, which locates in the blood vessels in your eye. The doctor shines a bright light into your eye for 60-90 seconds, bringing the drug into active state and destroying the rogue blood vessels, thus slowing the rate of vision loss.�

Photodynamic Therapy is a simple procedure. The doctor injects a drug called verteporfin into your arm and shines a bright light into your eye to activate it. The drug adheres to the rogue blood vessels and destroys them, slowing the progress of AMD. Photodynamic Therapy does not harm surrounding healthy cells as does laser surgery. You must avoid bright lights for several days afterward, but that is it. The treatment takes 15-20 minutes and is performed in the doctor's office or clinic.�

"Laser photocoagulation" is not often used as a treatment these days as it can result in scars, which cause blind spots in the vision field. The reference book Ophthalmology states that of those suffering from wet AMD only 15%-20% exhibit the bleeding under the retina that would qualify them for the therapy.�

The pharmaceutical company Genentech is investigating the potential of its colorectal cancer drug, Avastin, which targets a protein thought to be in part responsible for AMD, as a possible treatment. This drug has it all over some others that must be injected directly into the eye - it's given intravenously. In some early tests, Avastin had a beneficial effect on vision within one week.�

Alcon, Inc. makes a substance called "Retaane," which has shown promise in preserving vision in all types of wet AMD. Early in 2005, Alcon revealed it anticipated a decision by the FDA in May. Retaane is said to attack enzymes that promote abnormal blood vessel growth by weakening their walls. Retaane isn't administered by injection, and treatment is only needed twice a year. another is that treatments are spaced about six months apart. The drug has been in clinical trials for several years.�

Genaera Corporation is testing out a drug called squalamine lactate, which also works to block abnormal blood vessel growth. It shows promise when combined with Visudyne.�

Then there's OXiGENE, Inc. They are testing an anti-tumor drug, combretastatin, for its efficacy in slowing stopping the development of AMD.�

A device known as the "TheraSight Ocular Brachytherapy System" uses low-rad x-rays to treat AMD. Clinical trials are going on now to find out to what degree the system can regulate the growth of rogue blood vessels in wet AMD. If you are interested in becoming part of these studies, click here for contact information and more details.�

Out of Japan about 20 years ago came a treatment called "membrane differential filtration." This procedure was credited with removing proteins and acids that contribute to the growth of AMD.�

A tiny instrument that can magnify images onto the retina to help with vision damaged by AMD, called the "implantable telescope" works by increasing the size of the image, which tends to reduce the center blind spot. This device is implanted in the eye. It is still being studied, but within a few years it should be available.�

Another treatment modality showing some promise is artificial retinas. Aimed at people who have suffered permanent vision loss from retinal disease. Optobionics is now testing the Artificial Silicon Retina (ASR) microchip for its reliability in encouraging healthy retinal cells in cases of retinitis pigmentosa and AMD.�

Low vision aids such as those which move the image to the perimeter of the vision field - to get away from the blank spot in the middle - have also shown promise. Some rather more cumbersome aids include handheld magnifiers, which may come with a small reading lamp; stronger reading glasses (bifocals with a powerful segment meant especially for reading); reading telescopes held in the hand or mounted on the nose in special padded frames; and magnifiers that project text onto a closed circuit TV (CCTV), monitor or regular computer or television screen.