The appearance of a black or dark grey spot in the centre of your vision signals a serious problem that may ultimately lead to blindness. Check each eye separately by looking at a lined pattern, such as wallpaper, with one eye covered. If the lines appear wavy and you see a dark spot in the middle, the cause may be macular degeneration, and you should see an eye care professional at once.
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Age-related macular degeneration (AMD) is an eye disease that shows up as a dark grey or blurry black spot, or a hole, in the centre of vision, often in one eye only. Over time, the progressive disease destroys central vision that is needed for reading and other close work as well as for driving and seeing distances. AMD generally does not affect side, or peripheral, vision. As the name suggests, AMD is the leading cause of vision loss in people over 60.
The macula is in the back of the eyeball, in the centre of the retina. There are two types of AMD: wet and dry. Wet AMD results from blood vessels growing under the macula and can cause loss of central vision very quickly.
Dry AMD, the most common form, is the result of cells in the macula breaking down and blurring vision. Gradually, the affected eye loses vision.
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Risk factors for AMD are age, overexposure to sunlight (UVA rays), smoking, family history, race and gender (AMD occurs more frequently among Caucasians and women), obesity, heredity and family history, high blood pressure and having light-coloured eyes.
For both wet and dry AMD, a common symptom is a blind spot in the centre of vision. An early sign of dry AMD is blurred vision, with details becoming difficult to distinguish. An early symptom of wet AMD is the wavy appearance of straight lines.
A visual acuity test, the traditional eye chart, administered by your eye care professional, will demonstrate your vision at various distances. Your eye doctor may also administer a dilated eye exam, using drops to widen your pupils, to examine the retina and optic nerve for signs of AMD as well as other eye problems. In a tonometry test, an instrument measures the pressure inside your eye.
An Amsler grid is a specific test for AMD. It is a grid-patterned chart with a black dot in the centre. You will be asked to stare at the dot and notice if some of the lines appear missing or wavy.
Your eye doctor may recommend that you see a retinal specialist who will administer further tests, including a fluorescein angiogram in which a dye is injected into your arm and photos are taken that identify leaking blood vessels. The specialist can determine whether you have AMD, whether it is the wet or dry form, and whether it is in advanced or intermediate stages.
Treatments for wet AMD include laser surgery, photodynamic therapy or injections of drugs directly into the eye. Photodynamic therapy combines a photosensitizing drug and a specific type of light.
While there is no known treatment to prevent vision loss from advanced dry AMD, a high-dose formulation of antioxidants and zinc has been found to slow the progression of AMD from intermediate to advanced. The Age-Related Eye Disease Study (AREDS) recommends specific amounts of vitamins C and E, beta carotene (vitamin A), zinc and copper. The AREDS formulation can be found in over-the-counter products, but you should consult with your physician before beginning such a regimen.