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Age Related Macular Degeneration

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Overview

Age-related macular degeneration (AMD) is the leading cause of vision loss in people over the age of 50, affecting approximately 1.4 million Canadians. The disease is “macular” because it damages the macula, which is the small, central portion of the retina, the light-sensitive tissue at the back of the eye that facilitates the cellular interactions that make sight possible. The macula is responsible for detailed, central vision, and is important for activities such as reading, driving, and distinguishing faces. While the disease is most commonly associated with ageing—hence “age-related”—there are some forms that can affect younger people and are caused by genetic, environmental, nutritional, and other factors, often simply called “macular degeneration.” In fact, the age-related form of the disease (AMD) involves risk factors outside of age that should be taken into account as well, including smoking, diet/nutrition, race (AMD is more common among Caucasians than African-Americans or Hispanics/Latinos), genetics, and family history of the disease.

A cross-section of the retina showing its different layers, including the layer of RPE cells. The photoreceptors are the elongated shapes standing vertically at the top, which are nourished by the RPE cells below them.

There are two kinds of AMD: dry AMD and wet AMD. The dry form is more common and less severe. It occurs when the macula becomes thinner and, as a result, less capable of supporting the retina’s photoreceptors, the cells that convert light into visual signals. Vision loss occurs as these cells die off.

The wet form of the disease is less common, affecting approximately one in ten people with AMD [1], and is a negative progression from dry AMD. In other words, dry AMD has the potential to develop into wet AMD. In the wet form, blood vessels below the thinning macula swell and begin to grow abnormally; if left untreated, they also begin to leak blood and fluid into the eye (hence “wet”). The cells directly affected by leaking vessels are called retinal pigment epithelial (RPE) cells, which nourish and sustain the sheet of light-sensitive photoreceptors above them. Since RPE cells play such a crucial role, their damage and loss during the advanced stages of wet AMD can entail rapid and severe vision loss. In AMD, such vision loss does not lead to blindness, but in the worst cases it causes significant loss of sight.

The below video provides a basic summary of wet AMD:

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In the earliest stages of AMD there may not be any noticeable symptoms. As a result, regular eye tests are essential: an ophthalmologist or optometrist will look for build-up of a yellowish deposit called drusen, which indicates the first stages of the macula’s deterioration. Early stages of AMD may also be accompanied by a slight blurring in the field of central vision. Such blurring can be detected via an eye test, but also at home using an Amsler Grid, a simple visual tool that can help you see distortions in your visual field. Please contact FBC if you would like us to send you a complimentary Amsler Grid. You can also download a copy here.

Images showing an Amsler Grid comparison: the left image shows how a healthy eye would see an Amsler Grid; the right image shows how an eye affected by the early stages of AMD may see a grid, involving a characteristic distortion with both vertical and horizontal misalignment. Image from the Canadian Association of Optometrists.

Eye care professionals will sometimes use an Amsler Grid as well, since it is a straightforward and reliable way to detect anomalies in central vision. Other tests that may be used during an exam include: a visual acuity test, which uses a chart to measure one’s ability to see at distances; a dilated eye exam, where the pupil is dilated with a drop so that the examiner can see into the eye using a specialized magnifying lens; a fluorescein angiogram, where pictures are taken as dye, injected through the arm, highlights leaking blood vessels and other issues; and optical coherence tomography, which uses light waves to take high-resolution images of the eye. In patients with wet AMD, visual distortion tends to be more significant and vision loss more rapid, particularly when the disease is left untreated. Ideally, if dry AMD is managed appropriately and steps are taken to adjust lifestyle and other factors, the disease will not turn “wet.”

Early-Stage AMD: Nutrition and Exercise 

Dry AMD does not have symptoms in the early stages and there are no treatments for this stage of dry AMD. Individuals living with early-stage AMD should get regular eye exams to monitor the disease progression.
If you have early-stage dry AMD, here are some things you can do to protect your vision:

Monitor any changes in your vision. If you notice any changes, report them to your eye doctor immediately.

  • Eat a variety of foods, including fish and colorful vegetables. A healthy lifestyle with a balanced diet may help slow or prevent dry AMD from advancing into later stages.
  • Get regular exercise. Many activities that protect your heart health may also protect your vision health. Speak with your doctor before starting any new exercise program.
  • Quit smoking. Smoking increases your risk of developing AMD and of the disease progressing.

Intermediate AMD or Late-Stage AMD: AREDS and AREDS2

Studies show that if you have intermediate or late stage AMD, nutrition supplements may slow disease progression. Age related eye disease study (AREDS) is a nutrition supplement that contains beta-carotene, vitamins C and E, zinc oxide, and cupric oxide. In the study, AREDS lowered the chance of dry-AMD progressing to wet AMD by 25%.[2]

AREDS2 is a newer supplement that was developed for smokers. Smoking combined with beta-carotene supplementation increases your risk of lung cancer. AREDS2 contains lutein and zeaxanthin instead of beta-carotene. Research shows AREDS2 are as effective as AREDS in protecting vision.

AREDS and AREDS2 supplements do not restore vision that has already been lost but may delay the onset of late AMD. They may also help slow vision loss in people who have late AMD but do not appear to help people with early AMD [3].

These vitamins are available without a prescription, but you should consult with an ophthalmologist or family doctor before starting any new supplements.

Wet AMD: Anti-VEGF Treatments as Standard of Care

Vascular endothelial growth factor (VEGF) is produced in the body and encourages new blood vessels to form. In wet AMD, the amount of VEGF increases in the eye and leads to uncontrolled growth of blood vessels in the eye. Anti-VEGF treatments block VEGF from working and can prevent and in some cases reverse vision loss. They are the standard of care for most cases of wet AMD. There are different types of anti-VEGF drugs. While they all reduce blood vessel growth they may have different ways of working and different risks and benefits.

The most common anti-VEGF drugs in Canada are:

  • Ranibizumab (Lucentis®)
  • Aflibercept (Eylea®)
  • Bevacizumab (Avastin®)*

A new drug called brolucizumab (Beovu®) was also recently approved.

These drugs all work in slightly different ways and may have different injection frequencies and side effects. Some of these drugs may not be funded by your provincial health plan. You should discuss with your doctor to find out which treatments are right for you.

*Note: Bevacizumab (Avastin®) was developed to treat cancer and was never submitted for approval to Health Canada for the treatment of eye disease. Most Ophthalmologists and the regulatory body CADTH consider it safe to use for eye disease however its use to treat eye disease is considered “off label.”

Wet AMD: Photodynamic Therapy

During this treatment a drug called verteporfin (Visudyne®) is injected into your arm and it travels to the blood vessels in your eye. Visudyne is then activated by a laser and together this can reduce blood vessels leaking. This form of combined drug and laser therapy is sometimes used along with anti-VEGF treatments for specific types of wet AMD.

Wet AMD: Laser Surgery

Laser surgery is a treatment for wet AMD that has not responded to any other treatments. The doctor uses laser to seal abnormal blood vessels at the back of the eye and stop them from leaking. Laser surgery may help to slow down vision loss but does not restore vision. Laser surgery causes scarring and can create blind spots and is only used in unique cases.

Clinical trials are essential to the scientific process of developing new treatments: they test the viability and safety of experimental drugs and techniques, called “interventions,” on human beings. While there is no guarantee that enrolling in a clinical trial will provide any medical benefit, some patients do experience positive results after receiving an experimental therapy.

READ OUR CLINICAL TRIALS GUIDE

The website clinicaltrials.gov is a centralized database of clinical trials that are offered globally. But as the disclaimer on the site’s home page states, there is no guarantee that a listed trial has been evaluated or approved—the National Institutes of Health runs the site but does not vet its content. This means that there could be bogus or dangerous trials listed that are preying on patients. It is essential that you discuss a clinical trial with your ophthalmologist before enrolling, and that you pay close attention to enrollment criteria.

If you are interested in exploring what is available on the site you can click on the button below, which will take you to clinicaltrials.gov and initiate a search for trials relevant for patients living with age-related macular degeneration.

CLINICAL TRIALS FOR AMD

Many research groups are working to develop treatment and cures for AMD. This includes treatments to reduce the symptoms that are causing vision loss, to stop photoreceptor cell death and even to restore vision when it has already been lost. FBC is proudly funding vision research in all these areas.

Some of the most promising and exciting areas of research are:

  • Looking for ways to improve the outcomes of anti-VEGF treatment, or improve the patient experience by developing treatments that reduce the frequency of injections
  • Gene Therapy introduces a new gene into retinal cells. It is being tested as a treatment for both dry and wet AMD. Scientists are studying if gene therapy can be used to prevent photoreceptor cell death, to deliver a permanent source of anti-VEGF or to reduce progression from dry to wet AMD.
  • Clinical trials are underway to test if stem cell therapies can replace retinal cells that that are damaged or lost in advanced AMD.
  • Retinal prosthetics such as the Argus II or “Bionic Eye” use computer technology to generate vision. Research is underway to test if retinal prosthetics may help to restore vision to people living with AMD.

With the generous support of donors, FBC has funded research in all of these areas. This includes support for the first Canadian Trial of the Argus II and research into gene and stem cell therapies. Click on the button below to learn more about the projects that FBC is currently funding:

FBC FUNDED RESEARCH

The page you are now on provides information on age-related macular degeneration, but Fighting Blindness Canada has developed additional resources that can be helpful in plotting an optimal path through vision care. Below is a link to our must-read resources, where you will find information on genetic testing, clinical trials, stem cell research, and more as well as a link to Vision Quest (FBC’s in-person educational events). The list will update as new resources are added.

Content last reviewed: September, 2020

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