Age-related Macular Degeneration

AMD is caused by deterioration of the retina and can severely impair vision.

There is currently no cure for AMD, but it can be treated with vitamins, laser therapy, medications, and vision aids.

It is a chronic irreversible medical condition that results in loss of central vision because of the damage to the macula, or central part of the retina. AMD is a major cause of blindness in those over 50 years old. The condition can make it difficult to read or recognise faces, although sufficient peripheral vision (vision outside the central area of your gaze) remains to allow you to continue with other daily activities. However, driving and reading will be affected.

AMD is classified into two main types:

• Dry form: The "dry" form of macular degeneration is characterised by the presence of yellow deposits, called drusen, in the macula. A few small drusen may not cause changes in vision. However, as they grow in size and increase in number, they may lead to a dimming or distortion of vision that people find most noticeable when they read. In more advanced stages of dry macular degeneration, there is also a thinning of the light-sensitive layer of cells in the macula leading to atrophy, or tissue death. In the atrophic form of dry macular degeneration, patients may have blind spots in the centre of their vision. In the advanced stages, patients lose central vision.
• Wet form: Is the more serious of the two forms. The "wet" form of macular degeneration is characterised by the growth of abnormal blood vessels from the choroid underneath the macula. This is called choroidal neovascularisation. These blood vessels leak blood and fluid into the retina, causing a distortion of vision that makes straight lines look wavy, as well as causing blind spots and loss of central vision. Bleeding from these abnormal blood vessels eventually form a scar, leading to permanent loss of central vision

Most patients with macular degeneration have the dry form of the disease and can lose some form of central vision. However, the dry form of macular degeneration can lead to the wet form. Although only about 10% of people with macular degeneration develop the wet form, they make up the majority of those who experience serious vision loss from the disease.

It is very important for people with macular degeneration to monitor their eyesight carefully and see their eye doctor on a regular basis.

In its early stages, macular degeneration may not have symptoms and may be unrecognised until it progresses or affects both eyes. The first sign of macular degeneration is usually blurred vision with a dim, blurry spot in the middle of your vision. This spot may get bigger or darker over time.

Symptoms of macular degeneration include:

• Gradual or rapid onset of blurred vision, especially in your central vision
• Shadows or missing areas of vision
• Distorted vision, e.g., a grid of straight lines appears wavy and parts of the grid may appear blank
• Problems discerning colours, specifically dark colours from other dark colours and light colours from other light colours
• Slow recovery of visual function after exposure to bright light
• Loss in contrast sensitivity (ability to tell different levels of luminaries or brightness apart)

If you experience any of these symptoms, see an eye specialist as soon as possible.

AMD can be detected in a routine eye exam. One of the most common early signs of macular degeneration is the presence of drusen -- tiny yellow deposits under the retina -- or pigment clumping. Your doctor can see these when examining the eyes. Your doctor may also ask you to look at an Amsler grid -- a pattern of straight lines that resemble a checkerboard. If some of the straight lines appear wavy, or you notice that some of the lines are missing, you could be experiencing early macular degeneration.

If your doctor detects AMD, a procedure called angiography or an Optical Coherence Tomography (OCT) may be performed on you. In angiography, a dye is injected into a vein in the arm. Photographs are taken as the dye reaches the eye and flows through the blood vessels of the retina. If there are new vessels or vessels leaking fluid or blood in the macula, the photographs will show their exact location and type. OCT is able to see fluid or blood underneath the retina without using dye.

Early detection of age-related macular degeneration is very important because there are treatments that can delay or reduce the severity of the disease.

Your risk increases with the following:

• Adults over age 60
• If you have a family history of the condition, you may have a higher risk of developing macular degeneration
• Smoking
• High blood pressure
• High cholesterol
• Obesity
• Light skinned
• Having a light eye colour

There is currently no cure for macular degeneration, but treatments may prevent severe vision loss or slow the progression of the disease considerably. Several options are available, including:

• Anti-angiogenesis drugs like (Avastin, Eyelea, Lucentis, Macugen) block the development of new blood vessels and leakage from the abnormal vessels within the eye that cause wet macular degeneration. This treatment has been an improvement over previous treatment methods, and many patients have actually regained vision that was lost. The treatment may need to be repeated during follow-up visits.
• Laser therapy with High-energy laser light can sometimes be used to destroy actively growing abnormal blood vessels that occur in macular degeneration.
• Photodynamic laser therapy is a two-step treatment in which a light-sensitive drug (Visudyne) is used to damage the abnormal blood vessels. A doctor injects the drug into the bloodstream to be absorbed by the abnormal blood vessels in the eye. The doctor then shines a cold laser into the eye to activate the drug, damaging the abnormal blood vessels.
• Low-vision aids are devices that have special lenses or electronic systems that produce enlarged images of nearby objects. They help people who have vision loss from macular degeneration make the most of their remaining vision.

People rarely lose all of their vision from age-related macular degeneration. They may have poor central vision, but they are still able to perform many normal daily activities.

The wet form of macular degeneration is a leading cause of irreversible vision loss. When both eyes are affected, you may experience a significant decrease in your quality of life.

The dry form of age-related macular degeneration is much more common and tends to progress more slowly, allowing you to keep most of your vision.

Unfortunately, even after wet macular degeneration treatment, the condition can recur and require repeated treatments. Because of this, individuals with macular degeneration must test their own vision regularly and follow the recommendations of their ophthalmologist. Successful and timely treatment will slow the rate of vision loss and often improve vision.

Using a screening tool called the Amsler grid may help detect subtle changes in your vision. You can monitor your vision daily by looking at an Amsler grid. You should also stop smoking, eat a balanced diet that includes leafy green vegetables, and protect your eyes from UV light by wearing protective sunglasses or head gear with brims.