AGE RELATED MACULAR DEGENERATION.

As we age, the macula (the small part of the retina at the back of the eye that provides sharpness of vision) begins to break down and produces small yellowish particles called drusen, which are seen in a fundus photograph and in a cross-sectional diagram above. These can be an early sign of macular degeneration, but they do not usually cause vision loss by themselves and not all patients who develop drusen go on to develop macular degeneration.                            

 

The dry or atrophic form of age-related macular degeneration, seen above in fundus photography and in a cross-sectional diagram, is the most common form of macular degeneration, accounting for about 90 percent of cases. Although this form of ARMD does not usually cause severe vision loss, it can progress to the wet form, so patients who have it should see their ophthalmologist regularly or assess their vision with the Amsler grid.

   

The wet or exudative form of ARMD, seen here in fundus photography and in a cross-sectional diagram, affects about 10 percent of ARMD patients. It is caused by the growth of abnormal blood vessels at the back of the eye that can leak fluid and blood. The wet form of ARMD typically causes significant vision problems in the affected eye and can progress very rapidly and cause permanent vision loss.

 

WHAT IS MACULAR DEGENERATION?

 

The eye is often compared to a camera. The front of the eye contains a lens that focuses images on the inside of the back of the eye. This area, called the retina, is covered with special nerve cells that react to light.

 

These nerve cells are very close together in the middle of the retina where the eye focuses the images that we see. This part of the retina is called the macula.

 

As people age, the macula tends to change in ways that cause a gradual loss of sharp vision. Sometimes, the macula actually begins to break down and produce small particles called drusen. In some eyes, the changes to the macula will eventually result in the growth of new blood vessels where they do not belong.

 

Both of these conditions are called age-related macular degeneration. If there are no new blood vessels being created, it is "dry" macular degeneration. When new blood vessels start to grow, it is called "wet" macular degeneration.

 

WHY DO PEOPLE GET MACULAR DEGENERATION?

 

No cause of macular degeneration has been proven. Things like smoking, exposure to direct sunlight over a period of years, a lack of vitamin A and some medical conditions seem to make people more likely to get macular degeneration. Some people also seem to inherit a tendency to have macular degeneration. None of these things can really be said to cause macular degeneration, however, and there is no sure way to prevent the condition.

 

HOW DOES THE DOCTOR DIAGNOSE MACULAR DEGENERATION?

 

The ophthalmologist may notice some things during the examination, or the patient may mention symptoms, that could be caused by macular degeneration. These are:

 

   * The ability to see fine details when one is looking directly at an object, no matter how close or far away it is, starts to decline.

   * Vision changes so that straight lines look wavy or broken.

   * Dark spots, lines, or shadows appear across the middle of the field of view.

 

When these symptoms are caused by macular degeneration, they can occur in just one eye or in both eyes. Usually, the problem is noticed first in one eye.

 

If you notice any of these symptoms it is important to make an appointment with your optometrist as soon as possible. He will use a special instrument to look inside the eye for signs that the macula is changing and if there is a problem they will refer you on to an ophthalmologist.

 

HOW IS MACULAR DEGENERATION TREATED?

 

Initially your ophthalmologist may recommend observation, the dry form of ARMD does not require active treatment. You will usually be given an Amsler grid to examine your vision every week or so. If  there is a sudden change in your vision with distortion then it is important to see an ophthalmologist for a flourescene  angiogram. This will help them to see if you have the “wet” type that is amenable to treatment. Even though vision might not change for months at a time, macular degeneration will never get better on its own. And when macular degeneration goes from the "dry" form to the "wet" form, there can be a permanent loss of vision.

 

HOW DO I DETECT IF THINGS ARE GETTING WORSE?

 

People with macular degeneration can check their own vision with a simple test called the Amsler grid.

 

The Amsler grid is a pattern of straight lines that make perfect squares. The patient looks at a large dot in the middle of the grid and notices any areas where the lines look blurry, wavy or broken. If the grid lines seem to be more distorted than before, it might be a sign that the macular degeneration is getting worse and needs treatment.

 

All of the treatments for macular degeneration are considered surgery. Some treatments just use a laser that is shined through the clear front part of the eye and focused on the macula. In other treatments, the surgeon makes openings in the eye for special instruments.

 

What happens in the operations to treat macular degeneration?

 

The procedures for macular degeneration are usually done under a local anaesthetic. That is, the patient is awake but does not feel the procedure.

 

Surgeons have several techniques to treat "wet" macular degeneration, including:

 

   * Laser photocoagulation. This procedure is used to stop the abnormal growth of blood vessels that happens in "wet" macular degeneration. The surgeon focuses a laser beam onto a small spot on the macula where blood vessels are growing. The laser beam heats up that spot, creating a tiny burn in the blood vessels and stopping their growth. Unfortunately, vision does not come back in the areas treated with the laser. It is also very likely that new blood vessels will grow at some time in the future.

   * Photodynamic therapy. In this treatment, a special dye is injected into the bloodstream. This dye is actually a type of medication that only becomes active when very strong light, such as a laser, is shined on it. The surgeon activates the medication by focusing a laser onto the abnormal blood vessels that are growing in the macula. The medication works from inside the blood vessels to shrink them. This treatment causes much less damage to the macula, so there is less loss of vision. But the growth of abnormal blood vessels still might happen again in the future.

   * Macular surgery. There are two other treatments the surgeon might recommend for severe cases of "wet" macular degeneration. In both of these procedures, the surgeon makes openings into the eye for special instruments. One technique is to remove the tissue where the abnormal blood vessels are growing. Another method is to lift the macula off the area where the blood vessels are growing and place it in a more healthy part of the retina. These procedures often do not fully restore normal vision, however.

   * Intravitreal injections. Avastin, Lucentis and Macugen can all be used in an attempt to get these new vessels to regress. In some cases not only does it prevent things from getting worse it can sometime lead to an improvement in the patients vision.

 

DOES EVERYONE WITH MACULAR DEGENERATION GO BLIND?

 

No. Even though vision might be blurry or lost in the middle of the field of view, macular degeneration does not affect vision off to the side. And with the treatments available today, people with macular degeneration have a good chance of keeping useful vision for many years. The best way to keep and use as much vision as possible is to have regular eye examinations and follow your doctor's advice.