What is Age-Related Macular Degeneration (AMD)?
Age-related macular degeneration (AMD), or simply macular degeneration, is a common eye disorder caused by deterioration of the macula, a small area of the retina located in the back of the eye. Macular degeneration is a known cause of central vision loss. For reference, central vision is what you see directly in front of you when looking straight ahead.
Peripheral vision is what you see to the side when you’re looking straight ahead. Macular degeneration doesn’t cause total blindness as it doesn’t affect one’s peripheral vision. It is estimated that over 12 million Americans suffer from this disease, and it is the #1 cause of vision loss. There are two primary types of macular degeneration:
Dry macular degeneration affects 85-90% of people with the condition. It is caused when small yellow deposits called drusen develop under the macula at the back of the retina. Wet macular degeneration affects the remaining 10-15% of people diagnosed with the condition. This form of AMD occurs when abnormal blood vessels develop under the retina and macula.
Symptoms of Macular Degeneration
Macular degeneration is a progressive disease, which means it will become worse as time passes. Many people do not notice vision problems in the early stages of the disease. It is also worth noting that one is less likely to notice vision changes when both eyes are affected at the same time. The warning signs and symptoms of dry macular degeneration include:
- a reduction in central vision
- a distortion of straight lines in your field of vision
- the need for brighter lighting
- difficulty adapting to low lights
- trouble recognizing faces
- retinal damage
The symptoms of wet macular degeneration are similar to those of dry macular degeneration, such as visual distortions and reduced central vision. However, if you have wet macular degeneration, you may also experience:
- a blurry spot in your field of vision
- a dark spot in the center of your vision due to blood vessels bleeding or leaking fluid
- hazy vision
- rapidly worsening symptoms
Wet macular degeneration progresses significantly faster than dry macular degeneration.
Treatment Options for Macular Degeneration
Currently, there is no known cure available for macular degeneration. However, your health care provider can recommend a number of options to help slow the progression of the disease.
Treatment for Wet Macular Degeneration
If you have been diagnosed with wet macular degeneration, you might benefit from working with a low-vision rehabilitation specialist. The specialist can teach you how to cope with and adjust to life while experiencing vision loss. Your health care provider may also suggest injections of a medication directly into your eye to slow the growth of new blood vessels. These medications are known as anti-vascular endothelial growth factor (anti-VEGF) drugs, and they include ranibizumab (Lucentis) and aflibercept (Eylea).
Another treatment option is photodynamic therapy. With this form of treatment, your doctor will inject medication into a vein in one of your arms. From there, they will use a special laser to close up leaking blood vessels. This type of therapy can improve your vision, but it may require multiple treatments to achieve the desired effect.
Photocoagulation is yet another treatment option for AMD. This treatment involves the use of high-energy laser beams to destroy abnormal blood vessels. The purpose of this therapy is to help stop bleeding and reduce further damage to your macula. However, even if photocoagulation is successful, abnormal blood vessels can regenerate and you may be required to undergo another treatment.
Treatment for Dry Macular Degeneration
If you have been diagnosed with dry macular degeneration, your health care provider may suggest working with a low-vision rehabilitation specialist. Additionally, they may recommend undergoing surgery to help improve your vision. During the surgery, they’ll implant a telescopic lens in your eye to replace the natural lens, which will magnify your depth and field of vision.
Macular Degeneration Causes and Risk Factors
It is currently unknown why some people develop macular degeneration while others do not. However, certain factors can increase your risk for developing the disease. These risk factors include:
being over the age of 55 years old
having a family history of macular degeneration
having cardiovascular disease
having high cholesterol
Recent research has demonstrated that macular degeneration disproportionately affects white people more than other segments of the population.
Diagnosing Macular Degeneration
It’s critically important to have an annual eye exam, even if your eyesight seems normal. During the exam, you should advise your doctor of any changes in your vision that you have experienced since your last visit. Your eye doctor can conduct a variety of tests to determine if you are suffering from macular degeneration. For example, they can employ the use of special eye drops to dilate your pupils and inspect the back of your eyes for signs of fluid, blood, or yellow deposits. Other diagnostic tests include:
Amsler Grid Test
During your eye exam, the doctor can evaluate your field of central vision by asking you to look at an Amsler grid, which is a basic grid pattern with a dot in the middle. If some of the lines on the grid appear irregular or misshapen, this can be a sign of wet macular degeneration. You can also use an Amsler grid at home. Simply download a printable Amsler grid and follow the steps below:
- Wear your glasses or contact lenses as normal.
- Hold the Amsler grid about 12–15 inches away from your face.
- Cover one of your eyes with your hand.
- Focus your other eye on the dot at the center of the grid.
- Notice whether the lines on the grid are faded, dark, broken, wavy, or otherwise irregular.
- Repeat on the other side.
Amsler grids are frequently used for diagnosis, in addition to monitoring disease progression. The intent is to monitor changes in the alignment of the lines, which may indicate disease progression. Your physician can advise know how frequently you should use the grid at home.
In fluorescein angiography, the doctor will inject a colored dye into a vein in your arm. The dye will eventually travel to your eye, allowing your doctor to examine the blood vessels. From there, they can use a special camera to take pictures of your eye and examine these pictures to look for abnormalities and changes.
Indocyanine Green Angiography
Indocyanine green angiography is very similar to fluorescein angiography. With this test, the doctor injects your arm with indocyanine green dye. They can use this test to confirm the results of fluorescein angiography and to help diagnose which type of macular degeneration you may have.
Optical Coherence Tomography
Optical coherence tomography involves taking cross-sectional images of the retinae to check for swelling, thickening or thinning. After you’ve been diagnosed with macular degeneration, your doctor can also use this test to determine how your eyes are responding to treatment.
Vitamins for Macular Degeneration
Certain vitamins may help slow the progression of late macular degeneration affecting only one eye or intermediate macular degeneration. The National Eye Institute (NEI) has sponsored two large studies to examine the role of nutritional supplementation in the disease. These studies are known as Age-Related Eye Disease Study (AREDS) and AREDS2.
In the initial study, researchers determined that daily vitamin supplementation reduced the 5-year risk of intermediate disease progressing to late disease by 25–30%. Vitamin supplements were also found to reduce the risk of vision loss by upwards of 19%. The original AREDS multivitamin formula, based on the findings of the 2001 study, includes:
- 500 milligrams (mg) of vitamin C
- 400 international units (IU) of vitamin E
- 80 mg of zinc
- 15 mg of beta carotene
- 2 mg of copper
Beta carotene is not recommended for people who smoke or used to smoke, as it increases the risk for developing lung cancer, according to a landmark 1994 study. According to a 2010 literature review, beta carotene also increases the risk of lung cancer in women. In 2013, the AREDS2 formula was introduced. It replaced beta carotene with two other carotenoids; lutein and zeaxanthin. AREDS2 contains:
- 500 mg of vitamin C
- 400 IU of vitamin E
- 80 mg of zinc
- 10 mg of lutein
- 2 mg of zeaxanthin
- 2 mg of copper
Tips for AMD Prevention
Experts have not yet determined a way to prevent macular degeneration. However, you can help mitigate your risk for the disease by maintaining a healthy lifestyle. This includes:
- quitting smoking if you smoke
- eating a healthy diet as often as possible
- maintaining a moderate weight
- exercising as much as possible
Complications of Macular Degeneration
One of the frustrating complications of macular degeneration is the inability to perform certain tasks on your own. As the disease progresses, it becomes increasingly difficult to read and perform similar activities. It’s not uncommon for people with macular degeneration to be unable to drive a car safely. If you are diagnosed with macular degeneration, you may have to complete a vision test periodically to ensure that you’re capable of operating a car safely. Other potential complications are as follows:
Depression and Anxiety
Up to 39% of individuals diagnosed with macular degeneration experience some form of depression, which can be partially attributed to vision loss. Anxiety is also very common. However, people with the condition and people without the condition experience similar rates of anxiety, so be sure to speak with your doctor if you’re experiencing the symptoms of depression or anxiety. A qualified medical professional can suggest treatments including medication, counselling or a support group for people with vision impairments, to help improve your mental health.
As your vision decreases, your brain may try to compensate by creating false images or hallucinations. This isn’t a symptom of a mental health problem. It’s estimated that anywhere from 10 to 40 percent of older people with visual impairment experience hallucinations due to low-vision stimulation.
Outlook for individuals with Macular Degeneration
Macular degeneration is not a preventable disease, but it’s possible to diagnose the condition early with regular dilated eye exams. Early treatment can help slow the disease progression and minimize the loss of vision. If you are experiencing the symptoms of macular degeneration or notice other changes in the quality of your vision, please make an appointment to have your eyes examined.