Macular Degeneration is the name given to certain conditions affecting the retina which causes loss of central vision. The macula is the small central part of the retina of the eye and it plays a critical role in vision. Millions of people throughout the world have been diagnosed with Age related Macular Degeneration, which is the leading cause of legal blindness in people over the age of 60. Early or juvenile onset Macular Degeneration is much less common.
Macular Degeneration, and several other diseases, that are characterised by degeneration of some portion of the retina, are difficult diseases to describe because they occur in many variations, and progress at different rates for different people.
There are two basic types of Macular degeneration - Age-related and early onset or Juvenile. They are thought to have different causes.
Age-related Macular Degeneration (referred to as AMD) usually does not develop until the sixth or seventh decade of life, although there are cases documented in patients as young as 40. Because of the later onset of this disease, it is difficult to determine if it is inherited, but studies are showing familial patterns of the condition, indicating that there may be genetic causes. There may also be other aspects of your health that are risk factors for Age-related Macular Degeneration; these will be discussed later in this booklet.
Early onset Macular Degeneration appears to be largely genetic; that is, it is a condition that is programmed into your cells and not caused by injury or infection or any other external agent. Certain genes that are necessary for normal vision give faulty messages to the cells in the macula, leading to their progressive degeneration and eventually to vision loss. Early onset Macular Degenerations are relatively rare. The symptoms of Macular Degeneration, like those of other retinal diseases, vary greatly and range in severity from one person to another. The most common symptoms are blurring of vision with particular difficulty discerning details, both up close and from a distance. People with Macular Degeneration may have blind spots, resulting in a dark or empty area in the centre of their field of vision. They may also notice distortions of lines and shapes, either in everyday objects (e.g. crooked door frames) or in tests given by the eye doctor. Colour vision may also be diminished, although peripheral vision and night vision usually remain unaffected.
Because Age-related Macular Degeneration could begin in one eye, the remaining good eye will take over on its own to compensate for vision loss. It may be some time before the second eye is seriously affected enough for an individual to notice vision problems. Others do notice a sudden loss of vision. If you experience a sudden vision loss or distortion, it is important that you see your eye care professional immediately.
Take the Amsler Grid Eye Test
Sit at a comfortable reading distance from the screen and cover left eye.
Focus right eye on the centre dot. All four corners of the square should be visible without removing gaze from the centre dot. All the lines should appear straight and continuous and the squares should be uniform in size.
Repeat the test with the other eye.
If the lines appear wavy, interrupted or missing; if colours other than black and white appear; if the squares appear unequal in size or if there are holes or spaces in the grid, contact your optometrist immediately. (Intermittent white dots appearing at the line intersections are a normal optical illusion.)
The Amsler Grid has been used since 1945 is a black and white grid pattern made of perfectly horizontal and vertical lines that can reveal signs of wet macular degeneration and other macula retinal disease. The above distorted grid indicates macular disease.