The eye disorder
macular degeneration is the deterioration of tissue in the part of the retina called the macula, which is responsible for central vision. Central vision is the specific type of vision that is used to read and see things clearly. While it almost never results in complete vision-loss, macular degeneration can cause enough vision impairment to reduce a person’s quality of life significantly.
There are two types of macular degeneration: wet and dry.
Wet macular degeneration occurs when abnormal blood vessels grow under the macula, in a process called choroidal neovascularization. When this occurs, blood and fluid is leaked into the retina and distort the patient’s vision. Eventually, these blood vessels scar over and cause permanent vision loss. Only 10% of all macular degeneration patients have this form of the disease, but it is often the form that causes the more severe vision impairment.
Dry macular degeneration occurs when yellow deposits called drusen appear in the macula. Initially, drusen does not affect the patient’s vision, but as the drusen grow in size and increase in number, they cause central vision loss. As dry macular degeneration develops into the most advanced stages, the light-sensitive tissue in the retina is often killed, resulting in atrophic degeneration, which causes blind spots or complete loss of central vision.
Causes & Risk Factors
While scientists aren’t sure of what exactly causes macular degeneration, they do know that the main risk factor is age. As one reaches the ages of 50 and 60, one’s chances of getting macular degeneration increase astronomically, which is why the disease is more commonly referred to as “age-related
macular degeneration” (emphasis added), or AMD.
Other risk factors include:
St John's Wort
- Race: White people are more at risk for AMD than African-Americans
- Family History: People who have a family history of AMD may have a higher risk of developing the disease.
- Gender: Women appear to be at greater risk than men
, an herbal remedy commonly used for depression that has been linked to the development cataracts
in humans is also suspected of being a cause of macular degeneration in animals.
The symptoms of AMD in both forms usually develop painlessly, and over a long period of time. For wet AMD, the first symptom is usually that straight lines appear crooked (the result of leaking blood vessels). For dry AMD, the first symptom is usually blurred vision. At first, the blurred vision can be corrected by increasing the light source in the area, but as more of the tissues die, it becomes harder and harder to see things like faces or printed words clearly. Other symptoms of AMD can include white-out areas in the vision, diminished color perception, difficulty adapting to low-light areas, small blind spots, and (in the case of more advanced AMD) hallucinations.
While there is currently no cure for AMD, there are several treatment options available that help slow the development of the disease. These treatment options include:
- Vitamins: For some people with dry macular degeneration in the more advanced stages, vitamins C, E, beta carotene, zinc and copper can decrease the risk of vision loss.
- Laser Therapy: High-energy laser light can sometimes be used to stop the growth of the abnormal growth of blood vessels in the macula that causes wet macular degeneration
- Photodynamic Laser Therapy: This is a two-step treatment in which a light sensitive drug is used to damage the abnormal blood vessels that develop in wet macular degeneration. A doctor injects the drug into the bloodstream to be absorbed by the abnormal blood vessels in the eye. The doctor then shines a cold laser into the eye to activate the drug, damaging the abnormal blood vessels.
- Anti-angiogenesis Drugs: New drugs are being used to slow down or prevent the growth of the abnormal blood vessels within the eye (angiogenesis being a word describing the growth of blood vessels)
- Low Vision Aids: Devices that have special lenses or electronic systems that produce enlarged images of nearby objects. While these aren’t really treatments for the disease itself, they help people who have vision loss from macular degeneration make the most of their remaining vision.
There are also a few experimental methods of treatment that doctors are currently developing, such as submacular surgery (where doctors surgically remove the blood vessels that are developing below the macula), and retinal translocation (where the macular center is relocated to a part of the retina where there are no blood vessels growing, so that the blood vessels that were once under the macula can now be safely destroyed with a laser).
Unfortunately, as mentioned earlier, there are no permanent cures for AMD, so even with treatment, it is up to the patient to be proactive about their eye health, and go in for regular medical check-ups to keep their vision strong.
St John's Wort (Hyperium Perforatum)