Macular degeneration is the leading cause of impaired reading or detailed vision. It is caused by the breakdown of the macula, the central portion of the retina. Although macular degeneration causes distortion of central and color vision, side vision is not affected.
What is the retina?
The retina is a thin layer of light sensitive tissue which lines the back of the eye. When light enters the eye, it is focused by the cornea and the lens onto the retina. The retina then transforms the light images into electrical impulses which are sent to the brain through the optic nerve.
What is the macula?
The macula is a very small area of the retina which is responsible for central vision and color vision. The macula allows us to read, drive, and perform detailed work. Surrounding the macula is the peripheral retina which is responsible for side vision and night vision.
What causes macular degeneration?
Macular degeneration is most commonly a natural result of the aging process. With time, the retinal tissues break down and become thin. This deterioration causes a loss of function of the macula.
In about 10% of cases of macular degeneration, aging of the retina is compounded by leakage of the tiny blood vessels which nourish the retina. Growth of new, abnormal blood vessels in the scar tissue that forms from the leaking blood vessels is also common. Blood and leaking fluid destroy the macula, causing vision to become distorted and blurred. The formation of dense scar tissue blocks out central vision to a severe degree.
Occasionally, macular degeneration is caused by injury, infection, or inflammation. The disease may also be hereditary.
What are the symptoms of macular degeneration?
The most notable symptom of macular degeneration is blurry or distorted central vision. Difficulty in reading, doing close work, or driving may also be noticed. A person with macular degeneration may experience blurry words on a page, distortion of the center of a scene, a dark or empty area in the center of vision, or the distortion of lines.
Macular degeneration may also cause a dimming of color vision. Fortunately, the disease does not cause total blindness, as side vision is not affected. Macular degeneration only affects central and color vision. However, if macular degeneration occurs in only one eye, the symptoms of the disease may not be noticed, as the "good" eye compensates for the "bad" eye.
How is macular degeneration diagnosed?
A lighted instrument called an ophthalmoscope is used to examine the retina. In addition, some special tests may be administered. The Amsler grid test, in which the patient looks at a page similar to graph paper, is used to detect blind spots or distortion of central vision. A color vision test will indicate damage to the macula if the patient cannot detect symbols or letters camouflaged in colored patterns.
If macular degeneration is detected, a procedure called fluorescein angiography may be done to check for blood vessel leakage. A dye, which quickly travels to the eye, is injected into the patient's arm. Photographs of the blood vessels in the retina are then taken to determine the extent of damage.
How is macular degeneration treated?
Unfortunately, there is no cure for macular degeneration. However, laser treatment may be used to slow the progression of the disease. Laser treatment can also be effective in sealing leaky blood vessels and destroying abnormal vessels so that hemorrhaging and scarring will not decrease central vision.
Low vision aids
People who suffer from macular degeneration are able to compensate for much of their vision loss through the use of low vision aids. Many magnifying devices, such as spectacles and hand or stand magnifiers, are available. Bright illumination for reading and other close work can also be helpful. Books, newspapers, and other materials are available in large print.
Prevention is the best medicine
Regular eye examinations are the only means of detecting macular degeneration, as the symptoms of the disease often go unnoticed. Early detection of macular degeneration may prevent further vision loss, since treatment is only effective when started early. Regular examinations are especially important for older adults and persons who have family members with a history of retinal problems.
If you are experiencing difficulty with central or color vision or have other vision problems, you should obtain a complete eye examination.