What is Macular Degeneration
A condition whereby the delicate cells of the macula become damaged and stop working. We do not know why this is, although it tends to happen as people get older. Vision loss usually occurs gradually and typically affects both eyes at different rates
In the early stages your central vision may become blurred or distorted, with things looking an unusual size or shape. This may happen quickly or develop over several months. You may be very sensitive to light or actually see lights that are not there. People with the advanced condition will often notice a blank patch or dark spot in the centre of their sight. This makes activities like reading, writing and recognizing small objects or faces very difficult.
The formation of new blood vessels and exudates ("drusen") from blood vessels in and under the macula is often the first physical sign that macular degeneration may develop.
The following are NOT known to be linked to macular degeneration: floaters (moving spots caused by debris floating in the vitreous fluid between the lens and the retina); dry eye syndromes; cataracts and cataract surgery.
What causes Macular Degeneration?
The root causes are still unknown. There are two forms of age-related macular degeneration , namely "wet" and "dry".
- For many people the visual cells simply cease to function, like the colors fading in an old photograph - this is known as 'dry' degeneration. 70% of patients have this "dry" form, which involves thinning of the macular tissues and disturbances in its pigmentation.
- The other 30% have the "wet" form, which can involve bleeding within and beneath the retina , opaque deposits, and eventually scar tissue . The "wet" form accounts for 90% of all cases of legal blindness amongst macular degeneration patients. The dry form will often begin to convert to wet, with the appearance of abnormal choroidal blood vessels - angiogenesis. The reason why angiogenesis occurs is unknown but it is believed that this additional blood vessel development is somehow caused by deposits being left in the back of the eye. These deposits are similar to age spots on the skin. These new blood vessels are fragile and have a propensity to leak and bleed, eventually forming scar tissue and resulting in irreversible vision loss.
- Different forms of macular degeneration may occur in younger patients. These non-age-related cases may be linked to heredity, diabetes, nutritional deficits, head injury, infection, or other factors.
- Inherited macular degeneration, which appears in some families but not in others, is known as macular dystrophy. Since macular degeneration affects most patients later in life, it is difficult to study successive generations in a family. Recent studies of twins indicate that both genetic and non-genetic factors play important roles in age-related macular degeneration. If several members of a family are sufferers then it is very important that other members have their eyes checked regularly.
- It has been demonstrated that the blue rays of the light spectrum seem to accelerate macular degeneration more than the others. This means that very bright light, such as sunlight or its reflection in the ocean and desert, may worsen macular degeneration. Special sunglasses that block out the blue end of the spectrum may decrease the progress of the disease.
- Hypertension tends to make some forms of macular degeneration worse, particularly in the "wet" form where the retinal tissues are invaded by new blood vessels. The medications used to treat hypertension have not been shown to have any direct effect on macular degeneration, but they may slow progression of the disease by reducing hypertension.
- Any type of smoking or exposure to tobacco smoke can accelerate the development of the "wet" type of macular degeneration.