Macular Degeneration

Age-Related Macular Degeneration (AMD) is a condition that can cause either gradual or sudden changes in vision as people age. This disease affects the macula, which is the centre of the retina. The macula is where more than 90% of all light entering the eye is focused on, so it is important to protect the macula as much as possible.

A healthy macula is crucial for reading, recognizing faces, driving, watching television, using a digital device, and carrying out other detailed visual tasks. AMD patients gradually lose their central vision, but their peripheral vision remains intact.

According to the Macular Disease Foundation, one in seven Australians over the age of 50 have some degree of AMD. Over the age of 80, around 15% of Australians will experience advanced AMD to the point where they will experience some level of vision loss or blindness. Statistically, AMD is slightly more common in women. There are different types of AMD and it can affect either one or both eyes. 

Types of Age-Related Macular Degeneration

Age-related macular degeneration can be divided into two main types:

Dry AMD

This condition is also called non-exudative or atrophic AMD. It is estimated that between 85 and 90 percent of AMD cases are dry type. The exact causes are unknown, but genetics and environmental factors are thought to play a part. Light-sensitive cells in the macula slowly deteriorate, generally one eye at a time. This condition can cause gradual vision loss if not well managed.

In dry AMD, proteins accumulate in the macula, causing the retinal cells above it to cease functioning. Protein deposits are known as drusen. The loss of vision is a gradual, painless process that occurs with dry AMD.  

There are three stages of AMD: early, intermediate, and late. These stages usually progress slowly over time. You cannot treat late-stage dry AMD, but there are ways to preserve your remaining vision. If only one eye has late-stage dry AMD, this can be a good opportunity to regularly monitor the other eye and do everything possible to prevent it from developing the same condition.

Wet AMD

This condition is also known as exudative AMD. It has been estimated by the American Macular Disease Foundation that about 10% to 15% of AMD cases are advanced or wet. Patients with this type of AMD often suffer more severe vision loss than those with dry AMD.

It is known as wet AMD because it is a condition whereby the macula can produce and leak fluids including VEGF (vascular endothelial growth factor) and blood. This can cause distortion and/or dark spots in the centre of your vision.

Usually, the first stage will be that an abnormal bulge forms in the macula due to fluid build-up, or there may be a leakage of blood that spreads throughout the eye. There may be dark spots in the middle of your field of vision. It may appear as if lines are curved when they are actually straight. 

 

Causes of Age-Related Macular Degeneration

AMD is not completely understood, but it is thought to be caused predominantly by genetics and the environment. Most people with the disease are older than 50 years of age. Risk factors may include:

  • Genetics

AMD is more likely to occur in people who have a family history of it, especially through their parents. Siblings with this condition can also be a prompt for people to be screened for this condition.

  • Smoking

Smoking significantly increases AMD risk.

  • Race

Statistics show that AMD is much more common in white people than in black or Hispanic people, while variants such as Polypoidal Choroidal Vasculopathy (PCV) tends to be more common in people from Asia.

  • Lifestyle 

AMD risk can be worsened by obesity, sedentary living, and eating diets high in saturated fats.

  •  UV exposure increases AMD risks

AMD might be triggered by harmful UV rays, but other research offers no conclusive evidence.

  • Other diseases

Diseases including hypertension, diabetes, and high cholesterol could also be responsible for causing AMD to develop. Diabetes in particular can lead to a similar condition to AMD known as diabetic retinopathy that will often be treated in a similar manner.

  •  Sex

A woman's risk of AMD is higher than for men, which is partially a result of women generally living longer and therefore having more opportunity to develop the condition.

  • AMD in one eye

When AMD is diagnosed in one eye, the chance of AMD in the other eye increases significantly.

 

Symptoms of Age-Related Macular Degeneration

Age- Related Macular degeneration is a disease that progresses. The symptoms will worsen as time passes. When the disease is in its early stages, you may not notice vision problems. When both eyes are affected at the same time, you will also notice fewer vision changes.

Signs and Symptoms of Dry AMD

  • The central vision will worsen.

  • A distorted view of straight lines will appear in your vision.

  • Brighter lighting will be needed.

  • Trouble adjusting to low lighting.

  • Blurriness.

  • Facial recognition problems.

Signs and Symptoms of Wet ARMD

  • Blurred areas of your vision, dark spots, and straight lines appearing wavy.

  • Blood vessels bleed or leak fluid, causing a dark spot in your field of vision.

  • Halos around lights.

  • This condition can get worse rapidly and requires prompt assessment.

 

Diagnosis of Age-Related Macular Degeneration

Even if your vision appears normal, it is vital to get your eyes examined annually. Inform your eye doctor if you experience any changes in your vision. Macular degeneration can be diagnosed by a variety of tests. These tests include:

Amsler Grid Test

When having an eye exam, your eye doctor may also ask you to look at an Amsler grid to assess your field of central vision. The Amsler grid has a dot at its centre and a basic grid pattern. If lines appear irregular on the grid or if there are dark areas, then this may be a sign of wet macular degeneration developing. If any changes are noticed, it is best to seek help from an optometrist or ophthalmologist as soon as possible.

Optical Coherence Tomography

A cross-sectional optical coherence tomography scan (OCT scan) reveals swelling, thickening, or thinning of the retina. This test can be performed by an optometrist or ophthalmologist. You may also undergo this type of test after a doctor diagnoses macular degeneration to determine if there is a response to treatment.

Fluorescein Angiography

This is a test performed by an ophthalmologist whereby a coloured fluorescein dye is injected into your arm. Your doctor can examine your eye's blood vessels once the dye has travelled to your eye. Once injected, your eye will be photographed repeatedly over the course of about five minutes with a fundus camera. The pictures will be examined to determine whether there is any leakage noted over time. This will help to diagnose AMD and will allow the ophthalmologist to determine the best course of treatment if problems are identified.

 

Treatment of Age-Related Macular Degeneration

There is no cure for AMD. The earlier treatment is started, the less severe the outcome may be. AMD symptoms can often recur, even after successful initial treatment meaning that treatment can be an ongoing process. Different treatments are available for different types of AMD.

Vitamins and Minerals

AREDS is a series of studies that examined patients with dry AMD. The study found that vitamins and minerals might help slow its progression. Vitamins C, E, lutein, zinc, copper, zeaxanthin, and beta-carotene are included in AREDS supplements. Smokers should not take beta carotene, however, as it can increase the risk of lung cancer. Always consult your doctor before commencing supplements to check for possible contraindications with existing medical conditions and medications.

Anti-Vascular Endothelial Growth Factor (Anti-VEGF)

For wet AMD, Anti-VEGF treatment is in the form of eye injections given by your ophthalmologist. This treatment blocks the production of VEGF, a blood vessel-growing protein. If you need this treatment, your eye will be numbed and cleaned thoroughly before then being injected with anti-VEGF. These treatments will usually occur monthly to start off with and then extended if deemed safe to do so by your ophthalmologist. In some cases, your vision can improve initially, but ongoing treatment is usually required to prevent a recurrence. Your ophthalmologist will discuss your treatment options with you and will typically either follow a) an ‘inject and extend’ approach whereby the interval between injections is gradually extended to determine the safest minimum interval wherein a recurrence does not occur or b) a reactive approach whereby treatments are administered only when recurrences happen.

Argon Laser

In certain conditions, argon laser may be a suitable treatment for sealing leaking blood vessels in the retina. This will be performed by an ophthalmologist. This treatment is usually only used for problems in the retina around the macula, as any treatment to the macula will cause central vision loss. This treatment may need to be repeated a few times depending on how much treatment can be tolerated in one sitting.

Prevention for Age-Related Macular Degeneration

No definitive preventive measures have been found for wet macular degeneration. However, it is possible to reduce your risk by maintaining a health-promoting lifestyle.

  • Smokers should stop smoking.

  • Consume healthy, nutrient-rich meals

  • Maintain a healthy weight

  • Stay active through regular exercise

Mark GoodrichAussieSpecsMacular Degeneration, Dry AMD, Wet AMD