Age-Related Macular Degeneration
Macular Degeneration Overview
As the eye looks straight ahead, the macula is the point of the retina upon which the light rays meet as they are focused by the cornea and the lens of the eye. Similar to the film in a camera, the retina receives the images that come through the camera-like lens. If the macula is damaged, the central part of the image is blocked, as if a blurred area had been placed in the center of the picture. The images around the blurred area may be clearly visible.
Macular degeneration is damage or breakdown of the macula. The eye still sees objects to the side, since side, or peripheral, vision is usually not affected. Macular degeneration alone does not result in total blindness. However, it can make reading or close work difficult or impossible without the use of special low vision optical aids.
Forms of Macular Degeneration
The most common form of macular degeneration is called dry or atrophic macular degeneration. This form accounts for 70% of all cases and is associated with aging. It is caused by a breakdown or thinning of the tissues in the macula.
About 10% of macular degeneration falls into a category called exudative macular degeneration. The macula is normally protected by a thin tissue that separates it from very fine blood vessels nourishing the back of the eye. Sometimes these blood vessels break or leak and cause scar tissue to form. This often leads to the growth of new abnormal blood vessels in the scar tissue. These newly formed vessels are especially fragile. They rupture easily and may leak. Blood and leaking fluid destroy the macula and cause further scarring. Vision becomes distorted and blurred, and dense scar tissue can block out central vision to a severe degree.
Other types of macular degeneration are inherited, may occur in children (juvenile macular degeneration), and are not associated with the aging process. Occasionally, injury, infection, or inflammation may also damage the delicate tissue of the macula.
If only one eye is affected, macular degeneration is hardly noticeable in the beginning stages, particularly when the other eye is normal. This condition often involves one eye at a time, so it may be some time before a patient notices visual problems.
Many patients do not realize they have a macular problem until blurred vision becomes obvious. Your eye doctor can detect macular degeneration in the early stages. The doctor examines the macula carefully to see if damage is present.
The Macular Degeneration Exam
The examination will usually include a few tests:
- A grid test, in which the patient looks at a test page similar to graph paper, will be used to evaluate the extent of sight loss spots.
- A color vision test will show whether a patient can tell color differences, and additional tests will help to discover conditions that may be causing the macula to deteriorate.
Sometimes the eye care professional injects a dye into the patient’s arm, and then takes photos of the retina.
Detection of Macular Degeneration
Macular degeneration can be detected and diagnosed early by an eye doctor if periodic eye examinations are part of health care. Early detection is important since people may not realize their vision is impaired. There is no cure for the most common form of macular degeneration—dry macular generation. However, ophthalmologic laser surgery has been used to slow the progression of the less common form, but only if this treatment is applied in the very early stages of the condition.
Who can treat Macular Degeneration?
A retinal specialist is the physician best suited to perform surgery in patients with macular degeneration. Both optometrists and general eye care professionals can prescribe nutritional supplements that can slow the progression of the disease. Newer treatment including intraocular steroids and blood vessel growth inhibitors are now being tried in patients with the wet type of macular degeneration with some success.
Macular Degeneration and You
A patient with macular degeneration can be helped. Low vision optical aids often improve vision for people with macular degeneration. Many different types of magnifying devices are available. Aids are best prescribed by an optometrist who specializes in low vision. However, many optometrists can help these patients with simple magnifiers and high power reading glasses. Bright illumination properly directed for reading and close work is often beneficial. Special lamps can also be helpful. Books, newspapers, and other items available in large print offer further help.
If you are over the age of 50, or if your family has a history of retinal problems, you should have your eyes checked periodically for signs of eye problems like macular degeneration. Early detection and subsequent treatment, if indicated, may help prevent additional visual loss.