WHAT IS MACULAR DEGENERATION?

March 26, 2018

 

Macular degeneration is a common eye disorder that causes the gradual deterioration of the retina in the eye, which results in vision loss in the centre of a person’s field of vision. The central region of the retina contains the macula lutea, which receives focused incoming light and is responsible for providing acute vision.

 

Macular degeneration doesn’t cause total blindness because it doesn’t affect your peripheral (side-ways) vision.

 

The most common form of macular degeneration is age-related macular degeneration (AMD or ARMD), which is why macular degeneration is often called age-related macular degeneration and this form is associated with one getting older and mainly affects people later in life, affecting approximately 14 percent of those over age 80.

 

In rare cases, macular degeneration can affect younger people. This is sometimes known as juvenile macular degeneration.

 

It can be present at birth or develop later, but it's almost always caused by an inherited genetic disorder, such as:

 

  • Stargardt's disease – the most common cause of juvenile macular degeneration, this can start in childhood or early adulthood.

  • Best's disease – also known as Best's vitelliform macular dystrophy.

  • Sorsby's dystrophy – this often begins between the ages of 30 and 40.

 

For reasons that are unclear, AMD is the most common cause of vision loss in the industrialized world and is most prevalent in populations of European descent and Chinese people. It tends to be more common in women than men.

 

There are two main types of AMD often referred to as dry and wet.

Dry AMD

Dry AMD develops when the cells of the macula become damaged by a build-up of deposits called drusen. It's the most common and least serious type of AMD, accounting for around 9 out of 10 cases.

 

Vision loss is gradual, occurring over many years. However, an estimated 1 in 10 people with dry AMD go on to develop wet AMD.

 
Wet AMD

Wet AMD, sometimes called neovascular AMD, develops when abnormal blood vessels sprout underneath the macula and damage its cells. It's thought these blood vessels form, as an attempt by the body to clear away the drusen from the retina. Unfortunately, the blood vessels form in the wrong place and cause more harm than good. They can leak blood and fluid into the eye, which can cause scarring and damage to your macula.

 

Wet AMD is more serious than dry AMD. Without treatment, vision can deteriorate within days.

The Macula

The macula is made up of millions of light-sensing cells that provide sharp, central vision. It is the most sensitive part of the retina, which is located at the central region of the retina, at the back of the eye. The retina turns light into electrical signals and then sends these electrical signals through the optic nerve to the brain, where they are translated into the images we see. This therefore means the retina processes visual images, with the macula being responsible for central vision. Central vision is what you see when you focus straight ahead. The macula is where incoming rays of light are focused. It helps you see things directly in front of you and is used for close, detailed activities, such as reading and writing. When the macula is damaged, the centre of your field of view may appear blurry, distorted, or dark.

 

As the eye ages the macula deteriorates and the central sharp vision that is used for seeing detail is gradually lost. This means tasks such as reading, driving and recognising faces become more difficult.

 

Macular degeneration differs from glaucoma, which is characterised by gradual loss of peripheral vision, and cataracts, in which the normally clear lens of the eye becomes cloudy.

Symptoms

AMD is not a painful condition. Some people don't realise they have it until they notice a loss of vision.

 

The main symptom of macular degeneration is blurring of your central vision. This means:

  • You lose visual acuity – the ability to see fine detail, so reading and driving become difficult  

  • You lose contrast sensitivity – the ability to distinguish between objects such as faces against a background 

  • Images, writing or faces can become distorted in the centre – most commonly associated with wet AMD

 

Your peripheral vision isn't affected. Glasses won't be able to correct your blurred central vision.

 

Both eyes tend to eventually be affected by AMD, although you may only notice problems in one eye to begin with.

 

Dry AMD

If you have dry AMD, it may take 5 to 10 years before your loss of vision significantly affects your daily life.

 

Sometimes your healthy eye will compensate for any blurring or vision loss if only one of your eyes is affected. This means it will take longer before your symptoms become noticeable.

 

You may have dry AMD if:

  • you need brighter light than normal when reading

  • text appears blurry

  • colours appear less vibrant

  • you have difficulty recognising people's faces

  • your vision seems hazy or less well defined

 

Wet AMD

In most cases, wet AMD develops in people who have already had dry AMD.

 

If you have wet AMD, any blurring in your central vision will suddenly worsen.

 

You may also experience other symptoms, such as:

  • visual distortions – for example, straight lines may appear wavy or crooked

  • blind spots – these usually appear in the middle of your visual field and become larger the longer they're left untreated

  • hallucinations – seeing shapes, people or animals that aren't really there

 

Wet AMD needs to be treated as soon as possible to stop your vision getting worse.

Diagnosis

Early symptom detection and diagnosis is important. In some cases, early age-related macular degeneration (AMD) may be detected during a routine eye test before it starts to cause symptoms.

The diagnosis of AMD is determined by the presence, number, and size of drusen under the retina. As the disease progresses, loss of the retinal cells can be seen on clinical exams.

 

Regular eye examinations are the best way to detect AMD, this should be conducted by an Ophthalmologist. If you experience any of the symptoms above, please make an appointment as soon as possible.

Causes

No one knows exactly what causes macular degeneration. Macular degeneration develops when the part of the eye responsible for central vision (the macula) is unable to function as effectively as it used to.

 

But research indicates it may be related to a combination of heredity and environmental factors, including smoking and diet.

Risk Factors

Factors that may increase your risk of macular degeneration include:

 

  • Age. This disease is most common in people over 65.

  • Family history and genetics. This disease has a hereditary component. Researchers have identified several genes that are related to developing the condition. AMD has been known to run in families. If your parents, brothers or sisters develop AMD, it's thought your risk of also developing the condition is increased. This suggests certain genes you inherit from your parents may increase your risk of getting AMD. However, it's not clear which genes are involved and how they're passed through families.

  • Smoking. A person who smokes is up to four times more likely to develop AMD than someone who's never smoked. The longer you've been smoking, the greater your risk of getting AMD. You're at even greater risk if you smoke and have a family history of AMD.

  • Race. Studies have found rates of AMD are highest in white and Chinese people, and lower in black people.

 

Other possible risk factors include:

  • Alcohol. It is possible drinking more than four units of alcohol a day over many years may increase your risk of developing early AMD.

  • Sunlight. If you're exposed to lots of sunlight during your lifetime, your risk of developing macular degeneration may be increased. To protect yourself, you should wear UV-absorbing sunglasses if you spend long periods of time outside in bright sunlight.

  • Obesity. Some studies have reported being obese (having a body mass index (BMI) of 30 or greater) may increase your chance of developing AMD.

  • High blood pressure and heart disease. There's some limited evidence that having a history of high blood pressure (hypertension) or coronary heart disease may increase your risk of developing AMD.

 

Reducing your risk

It's not always possible to prevent macular degeneration because it's not clear exactly what triggers the processes that cause the condition.

 

Your risk of developing AMD is closely linked to your age and whether you have a family history of the condition.

 

However, the following measures may help reduce your risk of developing AMD:

  • Stop smoking if you smoke

  • Eat a healthy, balanced diet that includes plenty of fruits and vegetables

  • Include fish and nuts in your diet – these foods contain omega-3 fatty acids, which may reduce the risk of developing macular degeneration

  • Cut down your consumption of alcohol to moderate levels 

  • Try to achieve or maintain a healthy weight and exercise regularly

  • Wear UV-absorbing glasses when outside for long periods

  • Manage other diseases, such as cardiovascular disease, high blood pressure, and high blood cholesterol

  • Go for regular eye check-ups

Treating Macular Degeneration

There is currently no cure for AMD. With dry AMD, treatment aims to help a person make the most of their remaining vision, for example, magnifying lenses can be used to make reading easier.

 

There's some evidence to suggest a diet rich in leafy green vegetables and fruit addition may slow the progression of dry AMD. The progression of AMD in those at greatest risk of losing vision can be slowed with high-dose dietary supplementation of vitamins C and E, beta-carotene, and zinc, all of which are thought to have an antioxidant function.

 

Wet AMD can be treated with anti-vascular endothelial growth factor (anti-VEGF) medication. This aims to stop your vision getting worse by preventing further blood vessels developing.

 

In some cases, laser surgery can also be used to destroy abnormal blood vessels.

 

The early diagnosis and treatment of wet AMD is essential for reducing the risk of severe vision loss.

 

Stem cell therapy

Research is underway to try to create new retinal cells using stem cells (the body's "master" cells). Stem cells can potentially be grown into retinal cells in the lab, and can then be transplanted.

 

A number of promising trials are currently being carried out across the world.

 

Coping and support

These tips may help you cope with your changing vision:

  • Ask your eye doctor to check your eyeglasses. If you wear contacts or glasses, be sure your prescription is up to date.

  • Use magnifiers. A variety of magnifying devices can help you with reading and other close-up work, such as sewing. Such devices include hand-held magnifying lenses or magnifying lenses you wear like glasses.

  • Change your computer display and add audio systems. Adjust the font size in your computer's settings. And adjust your monitor to show more contrast. You may also add speech-output systems or other technologies to your computer.

  • Use electronic reading aids and voice interface. Try large-print books, tablet computers and audio books. Some tablet and smartphone apps are designed to help people with low vision. And many of these devices now come with a voice recognition system, which can be a helpful low vision aid.

  • Select special appliances made for low vision. Some clocks, radios, telephones and other appliances have extra-large numbers. You may find it easier to watch a television with a larger high-definition screen, or you may want to sit closer to the screen.

  • Use brighter lights in your home. Better lighting helps with reading and other daily activities, and it may also reduce the risk of falling.

  • Consider your transportation options. If you drive, check with your doctor to see if it's safe to continue doing so. Be extra cautious in certain situations, such as driving at night, in heavy traffic or in bad weather. Use public transportation or ask family members to help, especially with night driving. Make arrangements to use local van or shuttle services, volunteer driving networks, or rideshares.

  • Get support. Having macular degeneration can be difficult, and you may need to make changes in your life. You may go through many emotions as you adjust. Consider talking to a counsellor or joining a support group. Spend time with supportive family members and friends.

     

     

     

     

     

     

     

     

     

 

 

....making effort to "STAY WELL"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

REFERENCE:

https://www.lei.org.au/services/eye-health-information/macular-degeneration/

https://nei.nih.gov/health/maculardegen/armd_facts

https://www.aao.org/eye-health/diseases/amd-macular-degeneration

http://www.allaboutvision.com/conditions/amd.htm

https://www.macular.org/what-macular-degeneration

https://www.medicinenet.com/macular_degeneration/article.htm

https://en.wikipedia.org/wiki/Macular_degeneration

https://www.britannica.com/science/macular-degeneration

https://www.nhs.uk/conditions/macular-degeneration/

https://www.mayoclinic.org/diseases-conditions/dry-macular-degeneration/symptoms-causes/syc-20350375

https://www.southerncross.co.nz/group/medical-library/macular-degeneration-causes-symptoms-treatment

https://www.healthline.com/health/macular-degeneration

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