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Eye Health Library / Eye Exam & Diagnoses
The macula is the central most part of the retina, the inner layer at the back of the eye responsible for detailed central vision. It is used for reading, driving and recognizing people’s faces. Macular degeneration is a condition that causes the center of your vision to blur while the side or peripheral vision remains unaffected. It is generally related to the aging process, and it is also commonly referred to as age-related macular degeneration (AMD). AMD is the leading cause of blindness in North America in adults over the age of 55.
In the earliest stages, macular degeneration is entirely symptom free but can be detected during routine eye health examinations. The most common initial symptom is slightly blurred central vision when performing tasks that require seeing detail. Glasses cannot correct this blurred spot or sense that there is an obstruction in the way of clear vision. Over time, the blurred area may increase in size and interfere with reading and recognizing faces. Other symptoms of AMD can cause straight lines to look wavy or distorted, and dark spots may blank out portions of the central vision. Patients experience no pain with AMD.
There are two types of AMD: dry and wet. The most common is the dry form. This is the milder form where there is a gradual degeneration of the central retinal tissues that make up the macula. Symptoms generally develop slowly over time. The wet form is a sudden leakage, or bleeding, from weak blood vessels under the macula. Symptoms of wet AMD progress rapidly. Wet AMD accounts for approximately 10 per cent of all cases, but the dry form can develop into the wet form over time. Any sudden change in vision should be assessed by your doctor of optometry as soon as possible.
The risk of developing AMD increases with age. High-risk groups include smokers and people who have had extensive UV exposure. AMD is also associated with conditions such as high blood pressure, arteriosclerosis, obesity and those with a family history of AMD. Individuals with diets high in fat, cholesterol and sugar, and low in antioxidants are more likely to be affected by age-related macular degeneration. Light eye colour has also been linked to an increased risk of developing AMD, as has a lack of physical activity.
Lifelong UV protection and good nutrition are believed to play a key role in preventing AMD. Living a healthy lifestyle by keeping your blood pressure down, reducing your intake of fatty foods and not smoking are all recommended. A diet high in antioxidants such as beta-carotene (a form of vitamin A), vitamins C and E, zinc, lutein, zeaxanthin, selenium and omega 3 fatty acids may help prevent AMD. Most of these antioxidants are found in green leafy vegetables, yellow and orange fruit, fish, and whole grains. Regular eye examinations by a doctor of optometry are also important in the early detection of AMD. Early signs of AMD may be found during an eye examination even if no symptoms are noticed. Your doctor of optometry can discuss ways to minimize the possibility of vision loss due to AMD.
Currently, dry AMD is treated with ocular vitamin supplementation and lifestyle modifications such as exercise, sunglasses to reduce UV radiation and smoking cessation. Many cases of wet AMD can be treated with medications injected into the eye to stop leaking blood vessels. Early detection and prompt intervention are crucial to addressing wet AMD. Certain vitamins can also assist in slowing down the progression of AMD. The use of vitamins will not reverse any vision loss that has already occurred, nor will it stop the progression of AMD completely. Regular eye examinations and counselling from your doctor of optometry will let you know when new treatments become available.
Many patients with sight loss due to AMD can benefit from low vision aids. Your doctor of optometry can prescribe magnifying devices to enhance both distance and reading vision. These aids will not restore sight to normal levels, but they allow people to maximize their remaining vision. Your doctor of optometry may also train you to use an Amsler grid, which is a very sensitive tool that can assist in testing the progression of AMD at home. It is important to contact your doctor of optometry if you notice any changes in your central vision.