FAQ's about Macular Degeneration
What is Macular Degeneration?
Macular degeneration is a condition of the eye that is often related to aging. It is commonly referred to as age-related macular degeneration and is abbreviated as AMD. In AMD the macula of the eye is affected. The macula is a light-sensitive tissue lining the back of the eye in the central area of the retina. The retina receives images of external objects and then sends them as impulses to the brain. The macula provides us with central vision and allows us to see fine detail such as recognizing a face reading or watching television. When the macula becomes damaged extreme and dramatic vision loss can occur.
What Causes Macular Degeneration?
While its cause is unknown the early or late stage of AMD affects over 9,000,000 people in the US and Canada over the age of 40. The late stage associated with vision loss is the most common cause of legal blindness in people over the age of 50 in the western world. In addition to age other factors may contribute to AMD. Nutrition plays a role and patients with light-coloured eyes those who smoke and those exposed to UV rays seem to especially vulnerable to AMD. The condition may also have a hereditary component which is why frequent eye exams are especially important for people with a family member already suffering from AMD.
What are the symptoms of AMD?
The early stages of AMD typically start with the appearance of spots beneath the retina. These spots called drusen are small round lesions that usually do not change vision very much. Most people with drusen will never have a serious loss of vision.
However certain changes can occur that lead to the late stage of AMD which is usually accompanied by vision loss. Most often vision loss starts in one eye. Because the healthy eye compensates for the loss of vision in the damaged eye macular degeneration may initially go unnoticed. In some cases it will also affect vision in the other eye.
How is AMD Detected?
In the early stages of AMD a person's vision may become blurred or distorted. An easy and effective way to test and possibility detect the smallest vision changes caused by wet AMD (explained below) when they first appear is by using the Amsler Grid. Many doctors give their patients this simple visual test to take home with them. An Amsler Grid enables you to test your vision on a regular basis and alert you doctor if there are any changes between regular eye exams. How to read the amsler grid.
What is Dry AMD?
When the early stage drusen are present for a long time they can cause the macula to become thinner (atrophic) and stop functioning. This is referred to as the dry form of AMD. This may cause some people to detect "blank" areas in their central vision. The dry type of macular degeneration is the most common affecting 85-90% of people with AMD and progresses very slowly.
How is Dry AMD treated?
Although there are no mainstream treatments currently available to reverse the effects of dry AMD new techniques are on the horizon. Recent studies have shown that a diet with an adequate intake of certain vitamins and minerals can potentially slow or halt its progression. In addition various vision aids including magnifiers are available to help people continue to live their lives as normally as possible.
What is Wet AMD?
The wet form of AMD affects only about 10-15% of people with AMD but is responsible for up to 90% of the severe vision loss associated with this condition. Wet AMD is caused by the growth of abnormal blood vessels across the macula and beneath the retinal pigment epithelium layer of the retina. As these abnormal vessels leak fluid and blood into the tissue at the back of the eye scar tissue typically forms and loss of vision may occur. Fortunately there are treatments available to prevent vision loss with certain types of wet AMD.
How is Wet AMD Treated?
There are currently two proven treatments available for people with wet AMD - laser photocoagulation and photodynamic therapy. In laser photocoagulation a laser delivers a concentrated beam of high-energy thermal light. When the light hits the part of the retina to be treated it turns to heat which destroys and seals the leaky blood vessels. As a result a scar forms in the area treated creating a permanent blind spot in the field of vision. This vision loss is usually less severe than the eventual loss of vision that would likely occur if no laser treatment were performed.
In photodynamic therapy a light-activated drug known as Visudyne is injected in the patient's bloodstream. Once the drug reaches the retina a non-thermal laser (a laser that does not burn the retina) activates it. This produces a clot that closes the abnormal vessels without causing damage to other parts of the retina. As a course of therapy typically six treatments at three-month intervals are needed to close all the leaking blood vessels and stop the progression of wet AMD.
How can you prevent or retard the progression of AMD?
Because the effects of AMD often go unnoticed until the damage is done it is difficult to prevent the condition. However taking preventive measures may help delay its progression. These include not smoking reducing exposure to UV sun rays by staying out of the sun or wearing protective sunglasses eating well and making sure you get the vitamins and minerals you need.
Do Nutritional Supplements Help?
A healthy diet high in antioxidant vitamins and minerals has long been associated with the prevention or delay of AMD. More recently a major study (commonly referred to as "AREDS") has demonstrated that supplementation with high levels of antioxidants and zinc can delay the progression of AMD and reduce vision loss in people with intermediate to advanced AMD. It is almost impossible to get such high levels of antioxidants through diet alone but there are nutritional supplements available that match the study formulation.
Other research indicates that two antioxidant carotenoids; lutein and zeaxanthin may help in the prevention of AMD by protecting the macula against blue light-damage. Good sources of lutein and zeaxanthin are green leafy vegetables especially spinach. These two antioxidants are also contained in some of the leading nutritional supplements.