Macular Degeneration

About

Macular degeneration (AMD) is a common eye disorder among people over 50. It causes blurred or reduced central vision, due to thinning of the macula. The macula is the part of the retina (back of the eye) responsible for clear vision in your direct line of sight.

There are two main types of macular degeneration wet and dry, the disease is classified in 3 stages: early, intermediate and late AMD. Dry macular degeneration, the most common type may first develop in one or both eyes and then affect both eyes. Over time, your vision may worsen and affect your ability to do things, such as read, drive and recognise faces. But this doesn’t mean you’ll lose all of your sight. Vision loss is typically central and people retain their peripheral vision. Some people have only mild central vision loss, while in others it can be more severe.

Early detection, regular eye tests and self-care measures may delay vision loss due to macular degeneration. Macular degeneration can progress to ‘wet’ macular degeneration when abnormal blood vessels develop under the retina which may leak and cause further vision loss.

Symptoms

Macular degeneration symptoms usually develop gradually and without pain. They may include:

• Visual distortions, such as straight lines seeming bent
• Reduced central vision in one or both eyes
• The need for brighter light when reading or doing close-up work
• Increased difficulty adapting to low light levels, such as when entering a dimly lit restaurant
• Increased blurriness of printed words
• Decreased intensity or brightness of colours
• Difficulty recognising faces
• A well-defined blurry spot or blind spot in your field of vision

Macular degeneration can affect one or both eyes. If only one eye is affected, you may not notice any changes in your vision because your good eye may compensate for the weak eye. The condition does not affect side (peripheral) vision, so it rarely causes total blindness.

When to see an optometrist:

• You notice changes in your central vision
• Your ability to see colours and fine detail becomes impaired

Causes

No one knows exactly what causes dry macular degeneration. But research indicates it may be affected by a combination of heredity and environmental factors, including smoking, obesity, diet and ageing.

The condition develops as the eye ages. Macular degeneration affects the macula — an area of the retina that’s responsible for clear vision in your direct line of sight. Over time, tissue in your macula may thin and lose cells responsible for vision.

Risk factors

Factors that may increase your risk of macular degeneration include:

• Age. This disease is most common in people over 60.
• Family history and genetics. This disease has a hereditary component. Researchers have identified several genes that are related to developing the condition.
• Race. Macular degeneration is more common in Caucasians.
• Smoking. Smoking cigarettes or being regularly exposed to smoke significantly increases your risk of macular degeneration.
• Obesity. Research indicates that being obese may increase your chance that early or intermediate macular degeneration will progress to the more severe form of the disease.
• Cardiovascular disease. If you have had diseases that affected your heart and blood vessels, you may be at higher risk of macular degeneration.

Complications

People whose dry macular degeneration has progressed to central vision loss have a higher risk of depression and social isolation. With profound loss of vision, people may see visual hallucinations (Charles Bonnet syndrome). And dry macular degeneration may progress to wet macular degeneration, which can cause rapid vision loss if left untreated.

Prevention

It’s important to have routine eye exams to identify early signs of macular degeneration. The following measures may help reduce your risk of developing dry macular degeneration:

• Manage your other medical conditions. For example, if you have cardiovascular disease or high blood pressure, take your medication and follow your doctor’s instructions for controlling the condition.
• Don’t smoke. Smokers are more likely to develop macular degeneration than are nonsmokers. Ask your doctor for help to stop smoking.
• Maintain a healthy weight and exercise regularly. If you need to lose weight, reduce the number of calories you eat and increase the amount of exercise you get each day.
• Choose a diet rich in fruits and vegetables. Choose a healthy diet that’s full of a variety of fruits and vegetables. These foods contain antioxidant vitamins that reduce your risk of developing macular degeneration.
• Include fish in your diet. Omega-3 fatty acids, which are found in fish, may reduce the risk of macular degeneration. Nuts, such as walnuts, also contain omega-3 fatty acids.

Diagnosis

Your optometrist may diagnose your condition by reviewing your medical and family history and conducting a complete eye exam. He or she may also do several other tests, including:

• Examination of the back of your eye. Your optometrist will put drops in your eyes to dilate them and use a special instrument to examine the back of your eye. He or she will look for a mottled appearance that’s caused by drusen – yellow deposits that form under the retina. People with macular degeneration often have many drusen. They may need to put dilating drops in your eyes.
• Test for defects in the centre of your vision. During an eye examination, your optometrist may use an Amsler grid to test for defects in the centre of your vision. Macular degeneration may cause some of the straight lines in the grid to look faded, broken or distorted.
• Optical coherence tomography (OCT). This noninvasive imaging test displays detailed cross-sectional images of the retina. It identifies areas of retina thinning, thickening or swelling. These can be caused by fluid accumulation from leaking blood vessels in and under your retina.

Treatment

At the moment, there is no treatment for dry macular degeneration. However, there are many clinical trials in progress. If your condition is diagnosed early, you can take steps to help slow its progression, such as taking vitamin supplements such as Macutec, eating a healthy diet and not smoking.

Low vision rehabilitation

Age-related macular degeneration does not affect your side (peripheral) vision and usually doesn’t cause total blindness. But it can reduce or eliminate your central vision — which is necessary for driving, reading and recognising people’s faces. It may be beneficial for you to work with a low vision rehabilitation specialist, your optometrist and others trained in low vision rehabilitation. They can help you find ways to adapt to your changing vision. A referral to Vision Australia can be helpful.

Information sourced from the Mayo Clinic https://www.mayoclinic.org/