Macular Degeneration
Age-related macular degeneration, AMD, is a disease of the eye linked to age, especially those over 50. It is the leading cause of severe vision loss and legal blindness in people over 50 in the western world.
It is usually slowly progressive, but can suddenly worsen. It is a disease of the macula, which is a small, specialized area of retina inside the back of the eye. The macula allows you to see fine details such as reading words or seeing distant objects. The rest of the retina lets you see the book but only the macula lets you see what is written.
There are two types of AMD: Dry AMD (85%) and Wet AMD (15%).
Dry AMD progresses slowly and is usually less severe but can eventually, over several years, cause loss of central vision. Peripheral or side-vision remains, and with the help of magnifiers and other visual aids you may continue to read large print.
Early detection is key as there are some vitamin combinations that have been shown scientifically to slow down the progression of the degeneration.
Wet AMD can cause sudden loss of vision in the affected eye and this may be irreversible. Usually it develops from areas of Dry AMD.
Risk factors for AMD
- Age : 8.5% for people 43-54 years old and upto 36.8% for people over 75 years old.
- Family history of AMD
- Females are more susceptible.
- Smoking history
- Diet poor in antioxidant vitamins and minerals, ie. few vegetables
What is Dry AMD?
Usually AMD starts in the dry form and in about 85% of the time stays that way. Yellow deposits, called drusen, accumulate in the lower layers of the retina due to a breakdown in the normal cell function. It is usually in both eyes. With time the drusen increase in both size and number, damaging the layers of the retina above (the rods and cones, etc) resulting in blank spots of vision. Progression to Wet AMD occurs in 43% of severe Dry AMD within 5 years.What is wet AMD?
Wet AMD is so named because blood enters the retinal tissue where it damages the delicate retinal layers. New abnormal weak blood vessels called choroidal neovascularization (CNV) push their way up into the retina, like weeds growing through cracks in the sidewalk, and being weak-walled and extremely delicate, they leak fluid and blood. This forms a” blister” in the macula and blocks central vision. Surprisingly, it is painless. Left alone a scar gradually forms, which usually causes severe loss of central vision,but peripheral vision is intact.How can I prevent AMD?
Getting regular checkups with your optometrist or ophthalmologist is important, as early stages are symptom free. If AMD is noted, an ophthalmologist should be part of your eye care team. You will be given an Amsler grid, which you should look at several times a week, one eye at a time, to help you determine if you are developing increasing blurred vision, blank spots or distortion. Distortion of straight lines is an early sign of progression to wet AMD. The use of vitamin supplements may be discussed with you as well as dietary changes as these may diminish the rate of the progression of disease.
A careful ocular examination along with diagnostic scans such as OCT will determine if you have Wet AMD. At that point you will be referred to a retinal specialist for consideration of treatment, which may include lasers and /or injections. These treatments in many cases may slow down or even reverse some of the damage that has occurred.
Although there is no treatment yet for dry ARMD, the AREDS (Age Related Eye Disease) Study published in 2001 by the National Eye Institute (USA) showed the benefits of prolonged use of antioxidant vitamins and zinc supplementation. Patients with minimal dry ARMD however did not show a significant benefit.
These vitamins don’t prevent AMD nor do they improve vision. Further studies begun in 2005, are presently underway to determine the effect of Lutein, Zeaxanthin and Omega 3 fatty acids. Other studies have shown benefits in regular intake of cold water fish(eg Salmon) high in Omega 3 fatty acidsBottom Line
- Visit your Eye Doctor regularly
- Take the specific vitamins recommended by your Eye Doctor
- If advised to do so, Do the Amsler grid test regularly and contact your Eye Doctor if changes occur
- Stop smoking
- Improve your diet by including a variety of fresh fruits and vegetables, especially dark leafy greens like spinach
- Maintain healthy body weight
- Wear sunglasses and a wide-brimmed hat outdoors to protect your eyes from direct UV light
- Visit ”www.amdcanada.com“
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Links & Resources
- AMD Canada
- American Academy of Ophthalmology
- American Association for Pediatric Ophthalmology and Strabismus
- American Society of Cataract and Refractive Surgery
- Association for Research in Vision and Ophthalmology
- Canadian Glaucoma society
- Canadian Ophthalmological Society
- Canadian Orthoptic Society
- CNIB (Canadian National Institute For the Blind)
- Eye smart
- Eye Smart – Know Your Risks, Save Your Sight
- Glaucoma Research Society of Canada
- Macular Degeneration Foundation
- National Eye Institute
- National Keratoconus Foundation
- North American Neuro-ophthalmology Society
- Retinal Neurophysiology and Anatomy
- Sjögren's Syndrome and Dry Eye
- The Foundation Fighting Blindness (Retinitis Pigmentosa)
- Vitreous Society – American Society of Retina Specialists
- What is Cataract Surgery?