Age related macular degeneration (AMD) is a disease associated with aging that gradually destroys sharp, central vision. Central vision is needed for seeing objects clearly and for common daily tasks such as reading and driving.
AMD is the leading cause of severe vision impairment inpeople aged over 40 years in Australia.1
AMD affects the macula which is the part of the eye that allows you to see fine detail. The retina is located in the centre of the retina and comprises the light-sensitive tissue at the back of the eye. It instantly converts light, or an image, into electrical impulses. The retina then sends these impulses, or nerve signals, to the brain.
There is no pain associated with AMD. In some cases, AMD advances so slowly that people notice very little change in their vision. In others, the disease progresses faster and may lead to a loss of vision in both eyes. AMD is a leading cause of vision loss in people who are 60 years of age and older.
AMD occurs in two forms: wet and dry.
Wet Age Related Macular Degeneration
Wet AMD occurs when abnormal blood vessels behind the retina start to grow underneath the macula. These new blood vessels tend to be very fragile and often leak blood and fluid. The blood and fluid raise the macula from its normal position at the back of the eye.
In this form of AMD, damage to the macula occurs rapidly, hence, with wet AMD, loss of central vision can occur quickly. Wet AMD is also known as advanced AMD. Unlike dry AMD, it does not have stages.
An early symptom of wet AMD is that straight lines appear wavy. If you notice this condition or any other changes to your vision, contact your eye care professional at once for a thorough examination of your retina.
Dry Age Related Macular Degeneration
Dry AMD occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye. As dry AMD gets worse, a blurred spot may appear in the centre of vision. Over time, as less of the macula functions, central vision is gradually lost in the affected eye. Scientists are still not sure what causes dry AMD.
The most common symptom of dry AMD is slightly blurred vision. It often begins with difficulty recognizing faces and the need for more light for reading and other tasks. Dry AMD generally affects both eyes, but vision can be lost in one eye while the other eye seems unaffected.
One of the most common early signs of dry AMD is drusen. Drusen are yellow deposits under the retina, often are found in people over age of 60. Your Insight Optometrist can detect drusen with specialist eye examination equipment.
Drusen alone do not usually cause vision loss. In fact, scientists are unclear about the connection between drusen and AMD. They do know, however, that an increase in the size or number of drusen raises a person’s risk of developing either advanced dry AMD or wet AMD. These changes can cause serious vision loss.
Dry AMD has three stages, all of which may occur in one or both eyes:
1. Early AMD
People with early AMD have either several small drusen or a few medium-sized drusen. At this stage, there are no symptoms and no vision loss.
2. Intermediate AMD
People with intermediate AMD have either many medium-sized drusen or one or more large drusen. Some people in this stage start to see a blurred spot in the centre of their vision and require more light for reading and other tasks.
3. Advanced Dry AMD
In addition to drusen, people with advanced dry AMD have a breakdown of light-sensitive cells and supporting tissue in the central retinal area. This breakdown can cause a blurred spot in the centre of vision. Over time, the blurred spot may get bigger and darker, taking more of the central vision People in this stage will start to have difficulty reading or recognizing faces until they are very close.
Who is at risk of AMD?
The greatest risk factor is age. Although AMD may occur during middle age, studies show that people over age 60 are clearly at greater risk than other age groups. For instance, a large study found that people in middle-age have about a 2 percent risk of getting AMD, but this risk increased to nearly 30 percent in those over age 75.
Other risk factors include:
• Smoking – Smoking may increase the risk of AMD.
• Obesity – Research studies suggest a link between obesity and the progression of early and intermediate stage AMD to advanced AMD.
• Race – European people are much more likely to lose vision from AMD than people of other races.
• Family history – Those with immediate family members who have AMD are at a higher risk of developing the disease.
• Gender – Women appear to be at greater risk of AMD than men.
Can lifestyle make a difference?
Lifestyle can play a role in reducing the risk of developing AMD.
-Eat a healthy diet high in green leafy vegetables and fish.
-Maintain normal blood pressure.
-Watch your weight.
Symptoms and Detection
Neither dry nor wet age related macular degeneration cause any pain.
For dry AMD: the most common early sign is blurred vision. As fewer cells in the macula are able to function, people will see details less clearly in front of them, such as faces or words in a book. Often this blurred vision will go away in brighter light. If the loss of these light-sensing cells becomes great, people may see a small–but growing–blind spot in the middle of their field of vision.
For wet AMD: the classic early symptom is that straight lines appear crooked. This results when fluid from the leaking blood vessels gathers and lifts the macula, distorting vision. A small blind spot may also appear in wet AMD, resulting in loss of one’s central vision.
How is AMD detected?
Your optometrist will be vigilantly watching for any signs of age related macular degeneration, especially if you are over the age of 60. Insight Optometrists carry out detailed retinal scans at every eye examination.
State-of-the-art equipment is used to produce high-resolution images of the retina at every eye examination. With the ultra-widefield imaging of Insight’s Optos equipment, up to 82% of the retina can be viewed at a time. This provides enough clinical information for early detection of eye diseases or disorders and allows monitoring of any conditions.
Insight Optometrists also use OCT or Optical Coherence Tomography to provide an ‘ultrasound’ image of the eye. This 3D section allows the most thorough diagnosis that technology can provide, which is extremely beneficial to AMD sufferers or potential candidates for AMD.
Treatment of Wet AMD
Wet age related macular degeneration can be treated with laser surgery, photodynamic therapy, and injections into the eye. None of these treatments is a cure for wet AMD. The disease and loss of vision may progress despite treatment.
Laser surgery. This procedure uses a laser to destroy the fragile, leaky blood vessels. A high energy beam of light is aimed directly onto the new blood vessels and destroys them, preventing further loss of vision. However, laser treatment may also destroy some surrounding healthy tissue and some vision. Only a small percentage of people with wet AMD can be treated with laser surgery. Laser surgery is more effective if the leaky blood vessels have developed away from the fovea, the central part of the macula. The risk of new blood vessels developing after laser treatment is high and repeated treatments may be necessary. In some cases, vision loss may progress despite repeated treatments.
Photodynamic therapy. A drug called verteporfin is injected into the arm. It travels throughout the body, including into the new blood vessels in the eye. The drug tends to “stick” to the surface of these new blood vessels. Next, a light is shined into the eye for about 90 seconds. The light activates the drug which then destroys the new blood vessels. Unlike laser surgery, this drug does not destroy surrounding healthy tissue. The process is quick and relatively painless. Photodynamic therapy leads to a slower rate of vision decline, however, it does not stop vision loss or restore vision in eyes already damaged by advanced AMD. Also, results often are temporary, requiring the treatment to be repeated.
Injections. Wet AMD is now treated with drugs that are injected into the eye, known as anti-VEGF therapy. Abnormally high levels of a specific growth factor occur in eyes with wet AMD to promote the growth of the abnormal new blood vessels. This drug treatment blocks the effects of the growth factor. Multiple injections will be required, that may be given monthly. This treatment can help slow down vision loss from AMD and in some cases improve sight.
Treatment of Dry AMD
Once dry age related macular degeneration reaches the advanced stage, no form of treatment can prevent vision loss. However, treatment can delay and possibly prevent intermediate AMD from progressing to the advanced stage, in which vision loss occurs.
The National Eye Institute’s Age-Related Eye Disease Study (AREDS) found that taking a specific high-dose formulation of antioxidants and zinc significantly reduces the risk of advanced AMD and its associated vision loss. Slowing age related macular degeneration’s progression from the intermediate stage to the advanced stage will save the vision of many people.
Don’t take any chances with your Macula. Book now for an Insight Optometrists eye examination to check and protect your eyesight from Macular Degeneration.
1. Vision Australia – Age Related Macular Degeneration Fact Sheet