What is Macular Degeneration?
Macular degeneration, also known as age-related macular degeneration (AMD), is a condition that can cause vision loss in the area of the eye responsible for sharp, central vision. AMD can make everyday activities, such as reading and seeing faces, difficult.
There are two types of AMD: wet macular degeneration (wet AMD) and dry macular degeneration (dry AMD). Both wet and dry macular degeneration affect several specific parts of the eye, and both wet and dry AMD can cause substantial vision loss.
How Macular Degeneration Affects the Eyes
The eye has three main layers, which lay flat against one another to form the eyeball:
Sclera – the “white” of the eye
Choroid – contains blood vessels and connective tissue; includes the iris and pupil
Retina – a paper-thin, light sensitive tissue lining the inside of the eye
Light carries visual information into the eye. The retina is the first layer of tissue that light strikes. The retina absorbs the light and changes the visual information into electrical impulses. The optic nerve at the back of the eye carries these impulses to the brain, which decodes the impulses into a visual image. Macular degeneration affects the retina’s ability to absorb light, which in turn, causes vision problems.
Specifically, macular degeneration affects the macula, which sits at the center of the retina. The macula contains the highest concentration of cones, which are photoreceptive cells responsible for providing sharp, detailed central vision. AMD causes the cones to degenerate in a way that prevents them from absorbing light correctly.
The retina consists of two layers:
Sensory retina – contains nerve cells that process visual information and send it to the brain
Retinal pigment epithelium (RPE) – sits between the sensory retina and the wall of the eye
The retinal pigment epithelium protects and nourishes the retina, removes waste products, and prevents new blood vessels from growing into the retina. It serves as a “pass through” between the retina and the choroid layer, which sits just behind the retina. The choroid layer contains blood vessels that pass through the RPE to nourish and cleanse the retina.
Dry macular degeneration occurs when parts of the macula get thin and tiny clumps of protein, known as drusen, grow.
- Dry AMD is more common as it is found in about 80 to 90 percent of all people with macular degeneration.
- It typically does not progress further than pigment discoloration and the presence of drusen.
- It tends to progress more slowly than wet AMD.
- Dry AMD could progress to wet AMD.
- Increased difficulty with night vision
- Printed texts appearing blurry
- Visual distortions, such as straight lines appearing wavy
- Reduced central vision in one or both eyes
- Lower sensitivity to colours
In wet AMD, abnormal blood vessels grow under the retina. These blood vessels leak blood and other body fluids that can damage and scar the macula.
- Wet AMD is less common as it occurs in about 10 to 20 percent of individuals with AMD.
- However, it is significantly more serious as it accounts for about 90 percent of all cases of severe vision loss caused by AMD.
- Vision loss occurs faster in those with wet AMD than it does for those with dry AMD.
- It is also called neovascular AMD or exudative AMD because it involves the exudation of fluid and blood from blood vessels.
- Symptoms quickly getting worse after you notice initial warning signs
- Decreased colour brightness
- Gray or blurry spot in the middle of your vision
- Visual distortions
- Overall hazy vision
Effects of AMD
Dry macular degeneration is a progressive disease, which means it gets worse over time. Sometimes the disease advances so slowly that the vision loss is not significant for a long time, while other times the dry macular degeneration progresses quickly.
Dry macular degeneration does not affect vision in its early stages. As the condition progresses, it causes an increasingly blurred area near the center of vision. This blurred area grows larger over time. In some cases, people develop blank spots in their central vision. They may also notice that objects do not seem as bright as they once were. Central vision may ultimately be lost although peripheral vision typically remains, but it is unable to provide clear, detailed vision. In most cases, people with advanced macular degeneration are legally blind.
It is possible to have AMD in only one eye, or to have different stages in each eye. A person can also have either or both types of macular degeneration. In other words, someone might have both wet macular degeneration and dry macular degeneration. Furthermore, dry AMD can suddenly change into wet macular degeneration. However, dry macular degeneration can advance and cause central vision loss without changing into the wet form of the disease. It is important to remember that not everyone with early AMD will develop advanced macular degeneration.
While someone with advanced dry macular degeneration does not experience total blindness, the loss of their central vision could significantly interfere with everyday activities, such as reading and driving. Damage to the macula causes blurry, dark or distorted images in the center of the field of view. Many people with AMD have trouble seeing faces, driving, reading, writing, or performing close work, such as cooking, sewing, or engaging in a favorite hobby. When looking at a clock, for example, someone living with this condition might see the clock’s numbers but not its hands.
Stages of Dry AMD
There are three main stages of dry macular degeneration, with the first stage causing very few symptoms and the last stage resulting in the total loss of central vision. Eye doctors do not classify wet macular degeneration in stages, as they always consider wet AMD as an advanced form of eye disease.
1. Early AMD
Drusen is present under the retina but most patients do not notice vision loss at this stage.
2. Intermediate AMD
Larger drusen are present in the retina, along with pigment changes. Some vision may be lost, but symptoms may not be noticeable.
3. Late AMD
Vision loss becomes noticeable due to either wet or dry AMD. Many people do not realize that they have macular degeneration until the damage to the macula has progressed enough to blur their vision. This underscores the importance of regular visits to an eye care professional, who can look for early signs before symptoms develop.
Prevalence of Macular Degeneration
Macular degeneration affects more than 10 million people in the United States, according to the American Macular Degeneration Foundation, more than cataracts and glaucoma combined. This makes macular degeneration the primary cause of vision loss in the nation. Macular degeneration affects nearly 1.5 million people in the United Kingdom and almost 1.4 million in Canada, and is the leading cause of blindness in developed countries.
Approximately 85 to 90 percent of all cases of AMD are dry macular degeneration, while 10 to 15 percent are the wet type.
As its name suggests, age-related macular degeneration predominately affects older adults. Another form of macular degeneration, known as Stargardt disease, is found in young people. Stargardt disease develops as the result of a recessive gene. Doctors often treat Stargardt disease with intraocular injections of anti-VEGF drugs, similar to the treatments for wet macular degeneration, in cases in which there is an abundance of blood vessels or in which the blood vessels are leaking.
Certain genetic and environmental factors increase the risk for macular degeneration.
Age is a major factor for both wet and dry macular degeneration. AMD is most likely to occur after the age of 60, although it can develop earlier.
More than 14 percent of white Americans age 80 and older have macular degeneration, according to the National Eye Institute.
Those with blue or light-coloured eyes may be at higher risk for developing dry AMD. This is because there is less pigment in blue eyes than in brown eyes, which makes light-coloured eyes more sensitive to light.
Smoking doubles the risk of the disease, which makes smoking the most controllable risk factor for developing macular degeneration. Smoking narrows the blood vessels, which reduces the supply of blood to the eyes.
A family history of the condition seems to increase the risk of developing macular degeneration, as an estimated 15 to 20 percent of those with macular degeneration have at least one parent, sibling, or other first-degree relative with AMD. Scientists have identified nearly 20 genes that influence the development of macular degeneration. Some of the involved genes are involved with the immune system, which protect the body from bacteria and viruses. These genes also trigger inflammation and remove debris, such as drusen, from cells and tissues.
Research shows that being obese seems to increase the chances that early or intermediate dry macular degeneration will progress to a more severe form of AMD. The studies have not yet revealed exactly how obesity triggers the progression of dry macular degeneration into another severe form or wet macular degeneration. Other risk factors for the progression of dry macular degeneration, such as cardiovascular disease and inactivity, may contribute to the role obesity plays in the progression of AMD.
Eye care professionals use a number of tools to diagnose both dry macular degeneration and wet macular degeneration. These tools help eye doctors look for vision loss and signs of changes to the macula.
Ophthalmologists test for central vision loss with the help of an Amsler grid, a simple square grid with a dot in the middle. The grid will appear to have straight lines for someone with normal vision whereas it will appear to have wavy lines or spots for someone with macular degeneration.
The eye doctor will also use a special lens to look inside the eye for signs of macular changes, as changes to the macula are often the first signs of dry AMD. The ophthalmologist may perform a fluorescein angiography, which is a special test that uses yellow dye and a special camera to detect abnormal blood vessels growing in the retina. Some eye care professionals use optical coherence tomography (OCT) machines that provide detailed images of the retina and macula.
Preventing Macular Degeneration
Certain measures can help reduce the risk of developing wet or dry AMD. These measures include:
Stop smoking, or never start, as current smokers have 2-3 times the risk of having AMD than non-smokers.
Eat oily fish, fruits, dark leafy greens
For those with dry macular degeneration, diet is the only way to slow down the progression of AMD. Consume lots of fruit, fish, and dark, leafy greens high in omega-3 fatty acids and antioxidant vitamins – research shows that people that ate oily fish containing these nutrients once a week had half the risk of developing wet macular degeneration than those who did not. In one study, the participants who ate the greatest amounts of refined carbohydrates were 17 percent more likely to develop AMD than were those participants who ate least.
Reduce refined carbohydrates
Reduce your intake of refined carbohydrates, such as white bread. Research shows an association between diets containing a high amount of refined carbohydrates and the onset and progression of macular degeneration.
Live an active lifestyle with plenty of exercise. Physical activity can boost the levels of antioxidants in the eyes. The results of some research suggest that people who engage in regular physical activity are 70 percent less likely to develop wet macular degeneration. While diet and other factors may explain the findings, physical activity reduces inflammation throughout the body and decreases irregularities in the cells lining the arteries.
Routine eye exams
Regular eye exams provide an opportunity to detect early signs of dry macular degeneration and wet AMD early. Drusen are usually the first sign of dry macular degeneration.
Community Resources and Support Groups
Although developing macular degeneration can be a difficult transition, you don’t have to go through it alone.
- FB – Macular Degeneration Support Group: supports and discusses the concerns of those with AMD
- FB – Macular Degeneration Xplained: doctors, artists, and creative writers make medical information about AMD easy to understand
- MD Support Group Directory: 218 international affiliate support groups work to support those with AMD
- MD Forum: an informal message board for those affected by MD
- Nature Research: research and reviews from Nature Research: a subset of Nature, the leading international weekly journal of science
- Medical News: latest research and news compiled about AMD
- All About Vision: news about AMD
- Macular Degeneration Association: news and research on AMD from a non-profit organization
Treatment for Dry AMD
There is currently no treatment for dry AMD, although nutritional supplements may slow its progression, according to the American Academy of Ophthalmology.
Treatment for Wet AMD
Medications known as anti-VEGF drugs can help treat wet macular degeneration by reducing the number of abnormal blood vessels in the retina, and by slowing the leakage of blood and other fluids from those blood vessels. Anti-VEGF is an acronym for “anti–vascular endothelial growth factor therapy.” The cells of the body produce a type of protein, known as vascular endothelial growth factor (VEGF), which produces new blood vessels when the body needs them. Sometimes the body produces too much VEGF, though, and this can lead to the growth of abnormal blood vessels in the eye. Anti-VEGF drugs, then, suppresses VEGF to slow the growth of new blood vessels associated with wet macular degeneration.
Three main anti-VEGF medicines:
Supplements can help slow the progression of dry macular degeneration for some people. These supplements include Vitamin C (500 mg), Vitamin E (400 IU), Lutein (10 mg), Zeaxanthin (2 mg), Zinc (80 mg), and Copper (2 mg).
Laser surgery may also reduce the presence of abnormal blood vessels and leakage that cause vision loss associated with wet macular degeneration.
Available Assistive Technology
Many successful eSight users live with central vision loss, which makes eSight a popular choice for those diagnosed with AMD.
eSight is a low vision eyewear device that functions by stimulating synaptic activity from the remaining photoreceptor function of the user’s eyes. Using a cutting edge camera, smart algorithms and high resolution screens, the assistive technology can provide the brain with increased visual information to naturally compensate for gaps in the user’s field of view. As a result, eSight makes clearer vision possible, resulting in enhanced vision of up to 7 lines on a doctor’s eye chart.
eSight and AMD
7 out of 10 users living with AMD experience significantly enhanced vision after trying eSight. eSight users like David Lee have been able to resume their favourite hobby of curling, and even win their curling provincial playdowns.
Although there are other technological options available to enhance vision for those with AMD, eSight is one of the only ones that boasts substantial mobility for its users.
Is macular degeneration hereditary?
Although not every type of AMD is hereditary, certain genes have been identified as being strongly associated with someone’s risk for AMD.
What is the best supplement for macular degeneration?
Taking certain nutritional supplements daily can lower the risk of developing AMD, and in some cases it may slow the disease for people early or intermediate AMD. These supplements include: Vitamin C (500 mg), Vitamin E (400 IU), Lutein (10 mg), Zeaxanthin (2 mg), Zinc (80 mg), and Copper (2 mg), according to the American Academy of Ophthalmology.
Can macular degeneration be cured?
Currently, there is no cure available for macular degeneration, but there are treatments like eSight which is a form of electronic eyewear that is clinically validated to enhance vision for people living with legal blindness, and improves the vision of 7 out of 10 users with macular degeneration who try it.
Are people with blue eyes more prone to developing macular degeneration?
Since there is less pigment in blue eyes than there is in brown eyes for example, more light is able to penetrate blue eyes. As a result, blue eyes are more sensitive to light which is what makes them more likely to develop AMD.
Can you get macular degeneration if you’re younger than 60?
Although it is much more common for those over 60, researchers found that even those under 50 can be affected by early AMD. In the age group of 35- to 44-year-olds, 3.8 percent of the subjects in the Gutenberg Health Study were found to be suffering from the disease.