The region of the retina responsible for sharp, central sight is the macula. In the macula, the nerve cells of the retina are composed mainly of cone cells closely clustered together. Cone cells are highly sensitive to light and make detail vision and the perception of colors possible. The macula is nearly one hundred times more sensitive than the peripheral regions of the eye. The central focus of light is upon the retina is in the region of the macula to provide high resolution vision.
A common condition that occurs as one ages is called a degeneration of the macula. This condition, known as age related macular degeneration (ARMD), describes this deterioration of the macula. An eye affected by macular degeneration will not be able to perceive detail or colors as well as a healthy eye.
Progressive deterioration of the macula can lead to loss of central sight. However, it does not lead to complete blindness because the peripheral regions of the retina remain unaffected.
Types and Causes
There are two forms of macular degeneration:
- The Dry Type: The dry type of macular degeneration is the most common form. In this type of macular degeneration, the delicate tissues of the macula become thin and cease to function properly.
- The Wet Type: The wet type of macular degeneration is less common, but is typically more damaging. The wet type of macular degeneration is caused by the growth of abnormal blood vessels behind the macula. The abnormal blood vessels tend to hemorrhage or leak, with the result being the formation of scar tissue if left untreated. In some instances, the dry type of macular degeneration can turn into the wet type.
Macular degeneration tends to have a higher incidence of occurrence when the following risk factors are present:
- Age: Macular degeneration can occur at any age; however, the chance of its occurrence increases nearly five-fold after the age of sixty-five.
- Heredity: Macular degeneration tends to “run in families.” This means that there is a genetic factor that predisposes a person toward developing the condition. Anytime a “bloodline” relative has macular degeneration, you run an increased chance of developing the condition.
- Gender: Women have a slightly higher incidence of developing macular degeneration than men.
- Ethnic Background: Fair-skinned people of northern European ancestry (Scandinavian, English, or German descent) have a higher chance of developing macular degeneration.
- Eye Color: Blue-eyed individuals are more prone to develop the condition than brown-eyed persons.
- Cardiovascular History: A history of heart disease or stroke is associated with a higher incidence of macular degeneration.
- Smoking: Macular degeneration tends to occur more frequently in persons who smoke. Even after treatment, smokers are reported to have a greater chance of having macular problems recur.
Symptoms and Diagnosis
Macular degeneration develops differently in each person. Because it will affect different regions of the macula from person to person, the symptoms tend to vary.
In general, the following symptoms are indicative of macular degeneration:
- The loss of the ability to see objects clearly.
- Vision that is noticeably distorted. Straight lines appear wavy. Objects may appear in wrong shape or size.
- The loss of clear, correct colors.
- A dark, empty area in the center of vision.
Care and Treatment
At the present time, there is no cure for macular degeneration. Depending upon the form of macular degeneration, there are treatments that can help to control the progression of the condition.
For an individual with macular degeneration, it is highly recommended that a regular schedule of eye examinations be maintained. During these examinations, detailed documentation is made through photographs and fluorescein angiography scans of the health of the retina. With this information, your eye doctor is better able to monitor the condition and note any changes that may occur.
Dry Macular Degeneration: This form of macular degeneration is the most insidious, for there is no form of treatment that is known to stop its progression, although vitamin supplements are often prescribed. Once the retinal tissues are affected by the dry type of macular degeneration, there is little that can be done to stop its slow progression and nothing has been found effective to restore sight lost to its effects.
Vitamins and Macular Degeneration: The first scientifically controlled study to show that antioxidant vitamins and minerals in very high dosages may decrease the progression of macular degeneration appeared in the Archives of Ophthalmology in October 2001. The recommended dosages are 5 times the normal amounts and should be discussed with your eye doctor and approved by one’s family physician prior to use as there can be significant undesirable side effects from high quantities of these supplements.
Wet Macular Degeneration: The wet form of macular degeneration has been controlled through laser treatments, provided they are performed at an early stage of the condition. The laser treatment seals the leaking blood vessels closed, halting the damage they can inflict upon the retina. These laser treatments are effective preventing or slowing the progress of wet type macular degeneration; however, no treatment has been discovered to restore sight lost to this condition.
If this form of macular degeneration is not treated, it tends to progress at a steady pace. As the condition progresses, it significantly reduces central sight.
At the present time, no cure has been discovered for macular degeneration. Likewise, no treatment has been found to restore central sight that has been lost to the condition.
Since several factors have been associated with an increased incidence of macular degeneration, many schools of thought subscribe to the idea that altering the risky behavior may reduce the incidence or severity of the condition. Some of the recommended lifestyle changes include the following:
- Eating a well balanced diet that is rich in leafy green vegetables, especially spinach.
- The use of a daily vitamin supplement that is rich in zinc. (Care should be taken not to take excessive doses of any vitamin or mineral).
- Wearing sunglasses with ultraviolet absorbing lenses.
- Maintaining a program of regular, cardiovascular exercise.
- Adhering to a low fat diet.
- Reducing serum blood cholesterol levels.
- Stopping smoking.
Macular degeneration causes a progressive loss of central sight; however, it does not cause total blindness. Peripheral vision is unaffected so one will always be able to get about in normal surroundings.
By making lifestyle adaptations and using low vision devices, people afflicted with macular degeneration can learn to cope and perform most activities of daily living. Low vision specialists can provide training in the use of magnifiers and closed circuit television systems for reading and some work activities. Large print books and magazines are available. With a persistent attitude and the support of family and friends, people afflicted with macular degeneration can continue to enjoy an active life.