AGE-RELATED MACULAR DEGENERATION (AMD)
As the baby boomer cohort approaches retirement age, vision loss and illness among the elderly will reach high proportions. Aging is the greatest risk factor for vision loss, and the leading cause is age-related macular degeneration (AMD), a condition that causes irreversible damage to vision.
At the back of the eye, there is a thin layer of light-sensitive tissue called the retina. Light is focused behind the retina onto a small spot called the macula. The macula then processes the details in the central part of our vision, and is responsible for humans being able to see detail, colours and to function in daylight. If the macula is unhealthy for any reason, the retina becomes like a glasses lens with a large smudge right in the middle; blurry central vision and loss of visual detail result.
There are two types of AMD. The “dry” type accounts for 90 per cent of cases, is slow-progressing, and occurs when the central part of the retina becomes pigmented, thinned or distorted. The more severe “wet” type takes place when blood vessels leak fluid and blood under the macula and into the retina. When the blood and fluid dry, a scar remains in the macula, which creates a black spot in your field of vision. Wet AMD can cause nearly complete vision loss within a period of weeks. In addition, the dry form can become wet at any time.
AMD affects nearly 2.1 million Canadians, and more than 1.6 million Americans aged 50 and over have late-stage AMD. In 2003 alone, 78,000 new cases were diagnosed in Canada. Imagine how many more there will be as the population continues to age! By age 60, one in 9 Canadians will have vision loss from AMD; by age 75, it is one in four, and by age 90, it is one in two. Despite these grim statistics, only a quarter of Canada’s population is even aware of the condition’s existence.
Although the vision loss caused by AMD is often irreparable, there are ways to slow the speed of the illness and possibly prevent it. Unfortunately, there is no known cause or agreed-upon therapy, so the following steps are solely recommendations you can take in the right direction, toward better eye health and a brighter future of vision:
- Quit smoking. It is thought to be the primary cause of one-third of AMD cases.
- Do not drink heavily. The risk of developing AMD is doubled if you’re a heavy drinker.
- Eat healthy, live healthy. Don’t spend an inordinate amount of time in the sun, and eat a lot of green vegetables and carrots.
For those already diagnosed with AMD and still in the early or mid-development stage, a combination of vitamin supplements (namely vitamins C and E, beta carotene, and zinc) can slow the disease’s progression by about 25 per cent.
Other forms of treatment are more radical and complex. Sometimes ophthalmologists use thermal lasers to close up damaged blood vessels in early wet AMD. You may need to undergo a test called an intravenous “fluorescein angiogram” to see whether lasers can help. Usually done on an out-patient basis at a hospital or clinic, this diagnostic test entails injecting fluorescent dye into a vein and then taking pictures of the dye as it circulates through the tiny blood vessels in the eye.
A more modern and often more useful form of therapy is photodynamic therapy (PDT). This method involves injecting a special dye just prior to treatment of the damaged and diseased macula. Next, an infrared laser is shone on the macula. The reaction between the dye and the light seals and dries up the abnormal blood vessels, resulting in better visual results.
For those with dry AMD, a unique process known as rheopheresis blood filtration (RHEO) is presently being performed in certain clinics. Generally, excess amounts of large proteins and fatty particles associated with certain diseases are filtered out so possibly harmful contaminants can be expelled. Studies suggest that RHEO-filtered blood flows more easily through eye capillaries, therefore slowing vision loss progression.
Newer drugs that shrink abnormal blood vessels are also currently being developed.
PLEASE NOTE: Before consuming any form of supplement or vitamin, it is imperative that you speak with our Optometrist.