Macular Degeneration

Age Related Macular Degeneration (AMD) causes a breakdown in the macula of the eye after age 50. It is separated from other diseases of the macula that occur at younger ages, most of which are rare and genetic in nature. AMD increases exponentially after age 70.1 Risk factors besides age are; smoking, female, Caucasian, blue eyes, cardiovascular disease, high blood pressure, poor diet, family history and ultra-violet exposure.2 Each year almost 78,000 Canadians are diagnosed with AMD, and this is expected to triple within the next 25 years. More than half of the CNIB’s clients suffer from AMD. 3

The Macula is the critical central part of the retina. The retina is analogous to the film of a camera and is the part of the eye that does the “seeing”. The macula contains the highest concentration of receptor cells in the retina and is responsible for our ability to see detail. Unfortunately, the trade-off in having the receptor cells (cones) so close together, is that there are very few support structures or repair mechanisms present in the macula. This is why the macula is more susceptible to damage and aging changes than the rest of the retina. It has been suggested that almost 80% of the macula is damaged before vision is noticeably affected. 4

Cardiovascular Disease. While something of an oversimplification, AMD is essentially caused by a break down in the blood circulation in the macula. All of the risk factors for heart disease have been identified as risk factors for AMD . 5 To prevent AMD, do the things we know are heart smart – healthy diet, exercise, control blood pressure and cholesterol, maintain a healthy weight, and don’t become diabetic.

Disclaimer: We have done our best to make accurate statements based on available studies published in peer-reviewed medical journals. However all studies are subject to interpretation. This article is not intended to replace medical advice, but simply to provide important information for our patients. Please discuss this information with your optometrist or family physician prior to acting upon the recommendations.

A Dry Topic. Many patients have heard AMD referred to as “Dry” or “Wet”. Essentially all AMD’s start out dry. Blood flow starts to slow causing a breakdown in the foundation of the macula (called the RPE). As the RPE is affected, even less blood and oxygen reaches the photoreceptors of the macula. Simultaneously carbon dioxide and other waste products are not flushed away and the receptors are slowly poisoned. In about 10% of patients, the eye detects this decline in oxygen and tries to heal itself by growing new blood vessels into the macula. This is certainly a case where the “fix” is worse than the original problem, as these new blood vessels are extremely fragile and will always break eventually. Once a vessel breaks, blood rushes out of the vessel and drowns the photoreceptors causing a relatively rapid decline in vision. Once new vessels start to grow in the macula, it is diagnosed as “wet”.

Dry AMD typically causes a gradual decline in vision over many years. The time from diagnosis to legal blindness is five to ten years. 6 Wet AMD causes a much more rapid loss of vision. Wet AMD accounts for 90% of severe vision loss in the elderly. There is no cure for either type of AMD. We now have a few treatments available for wet AMD to reduce the growth of vessels, thus slowing the dramatic loss of vision usually associated with this form of the disease. Our main goal is to prevent dry AMD from ever developing, and secondarily, if it does, prevent the disease from becoming wet. Our only weapon against AMD is prevention!

AREDS. Through the late 80’s and early 90’s a few small studies supported the notion that a healthy diet protects one against AMD. To further test this notion the National Eye Institute in the US sponsored a large scale study called The Age Related Eye Disease Study (AREDS). Between 1994 and 1998 over 3,600 participants aged 55 to 80 were followed. AREDS clearly showed a healthy diet and taking specific antioxidant supplements lessened the risk of dry AMD getting worse AND reduced the risk of those patients with dry AMD becoming wet.7 Since AREDS, numerous other studies have supported and expanded the recommendations of the importance of dietary supplements to lessen the devastating impact of AMD.

Our Recommendations. Based upon the published research, we make the following recommendations for our patients who are concerned about AMD. These recommendations are specifically about maintaining eye health. No mention is made about the importance of other vitamins and minerals, such as calcium which is so important for women to prevent osteoporosis, nor folic acid which is important to lower men’s risk of heart attack. We are only talking about age related eye disease here.

Family History of AMD. If you do not have AMD but have a family history, then quit smoking, wear sunglasses and ask for UV protection in your everyday glasses, maintain an appropriate Body Mass Index (BMI), eat at least 3 servings of fruit per day 8 and ensure you consume the following dietary supplements daily;

AREDS did not find a statistically significant benefit that the supplements used in their study prevented the development of AMD in those who did not have the disease at the start of the study. However, the main part of the study only followed participants for four years. Several studies since then have shown a very real benefit in preventing the development of AMD, especially with lutein and zeaxanthin. The following foods are rich in these two important nutrients; spinach, corn, egg yolk, kiwi, oranges, red grapes, zucchini, squash and kale. Over 95% of North Americans are deficient in omega 3 fatty acids. These essential oils have potent cardio-protective properties and boost our circulation. Flax seed oil is the best source for omega 3. Other excellent sources are salmon, cod, and halibut along with their oils ( salmon oils, cod liver oil). Four servings of fish per week has been shown to significantly reduce the risk of developing AMD. 9

Dry AMD. The following supplements are recommended, but note there is evidence that beta-carotene interferes with the absorption of lutein, and they should perhaps be taken at least an hour apart.10 Of course these do not have to be taken all at once, total dosage can be spread throughout the day.

A recent study demonstrated that those with dry AMD who take an aspirin a day, either one baby aspirin or one regular strength, reduce their risk of developing wet AMD.11

Sources for more information on the internet:

www.visionarts.ca
www.amdalliance.org
www.cnib.ca
www.amd.org
www.luteininfo.org
www.vitaluxvitamin.ca
www.alconlabs.com/ca_en/eo/conditions/armd.jhtml
www.bausch.com/ca_en/vision/seniors/
www.halls.md/ This page links to a good calculator of body mass index (BMI) and has further information on what the BMI is and why we need to pay attention to it.
www.usana.com Do a search for “visionex” supplements

References used in this article:

1. Ophthalmology, 2001 Apr;108(4):697-704
2. JAMA 1994; 272: 1413-1420
3. Info from CNIB web site
4. Eye, 1988;2;552-577
5. The ARED Study; Update II, 2003
6. BMJ 2003; 326: 485-8
7. JAMA 2001;286 (19): 2466
8. Arch Ophthalmol 2004 Jun: 122(6): 883-892
9. Arch Ophthalmol 2001 Aug: 119(8): 1191-9
10. Review of Optometry Vol 155, No. 5: 78
11. AM J Ophthalmol 2004 Apr:137 (4): 615-24