Age Related Macular Degeneration |
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Age Related Macular Degeneration (AMD) is one of the commonest causes of poor vision amongst elderly population and is very common in the western and developed countries. It is increasingly being recognised in Indian population as well, with almost 50% of those over 75 years old, having a degree of AMD. It affects the central area of the vision and periphery is well spared, but central area of the vision is needed for precision acts like reading, threading the needle etc.
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| The Retina |
The retina is at the back of the eye and acts like a film in a camera. It is the light sensitive layer of the eye and converts light into electrical signals that are then passed along the optic nerve to the brain to form the image we see.
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| The Macular Area |
Macula is a very small area on the retina at the back of the eye and is responsible for most of our central vision. Unfortunately, this is the part which macular degeneration affects. It does not affect the retina outside this area, which means that your peripheral vision (the outer range of your sight) is not changed. It is only the central vision that is affected, causing difficulty in reading, but not total blindness.
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Types of macular degeneration
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- Dry type – It is the common type of AMD and is a gradual thinning of the central retina which usually takes many years to develop. It may take years before it can cause significant decrease in vision.
- Wet or disciform type - happens when the body tries to heal the ageing retina by making new blood vessels grow. Unfortunately, these are very fragile and often bleed. This can lead to a sudden worsening of vision. Vision may become distorted causing straight lines to appear bent.
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| Amsler chart monitoring |
It is very important to monitor the vision regularly using a grid chart called Amsler’s chart to identify distortion in the field of vision which is a first sign of leakage of fluid and blood from the new vessels. Patients who notice sudden change in the vision with distortion of lines in the chart must report to any eye specialist for immediate eye check up. They can also monitor their vision by looking at straight lines like window or corner of the wall to identify the distortion at the earliest.
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Treatment options
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For dry form of AMD, there is no specific treatment. Although the condition may gradually worsen, it will never make you go completely blind. It only affects the central vision and the peripheral vision remains the same.
Some people have the wet form of AMD. Treatment depends on the type and stage of the condition. For some people, hot (Argon) laser treatment is appropriate; for others, cold laser or photodynamic therapy (PDT) is best. New modalities of treatment include intravitreal injections of Avastin, Lucentis and radiotherapy (called TTT, still investigational). Your consultant may also use an injection of steroid or antigrowth factor antibody into the vitreous cavity of your eye.
There is a great deal of research in this area and treatment options are constantly changing.
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| Role of glasses |
An up-to-date pair of glasses is needed. Full frame reading glasses are better than bifocals or varifocals (progressive). If you are having difficulty reading, Low Vision Aid may be needed as a magnifying aid. Additional lighting can help with reading.
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Preventive measures
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Young and old, must wear a pair of UV blocking sunglasses, together with a hat or a cap, when outside in the sun.
If you are a smoker - stop smoking - research has shown that smokers have a higher incidence of AMD. Stopping smoking will help decrease your overall risk as well as avoiding other medical problems.
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Role of dietary supplements
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Results from two Age-Related Eye Disease Studies published in 2001 and 2008 show that taking supplements containing high levels of antioxidants, vitamins,zinc, lutein and Zeaxanthine can significantly reduce the risk of advanced AMD.
People at high risk of developing advanced AMD lowered their risk by around 25% when they took a high-dose combination of vitamin C, vitamin E, beta-carotene and zinc. Other researchers feel that high levels of lutein and zeoxanthine may also be of benefit in reducing the risk of progression of AMD and there are several studies to support this.
The supplements helped patients with both the wet and dry forms of AMD. However, the supplements did not help those people with either early AMD or no AMD.
Previous studies have suggested that people with diets rich in green, leafy vegetables have a lower risk for developing AMD. However, the high levels of dietary supplements that were evaluated in the study are difficult to achieve from diet alone.
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Risks associated with dietary supplements
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A five year follow up of patients taking the high dose preparations has shown no significant side effects, other than a mild increase of non specific genito-urinary tract problems. Taking supplements containing zinc may cause a mild copper deficiency. Smokers taking beta carotene may develop increased risk of lung cancer. However, overall there were no serious side effects.
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General advice
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Television - sitting closer to the TV will help you see and will do no harm.
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