Do you find that you need more light than usual when you read? Is the newspaper becoming harder to read? Do you have difficulty recognizing simple street signs? If so, you may be suffering from a disorder that affects a large number of older Americans.

Age-related macular degeneration (AMD) is a chronic eye disease that occurs when tissue in the macula, the part of your retina that's responsible for central vision, deteriorates. The retina is the layer of tissue on the inside back wall of your eyeball. Degeneration of the macula results in blurred central vision or a blind spot in the center of your visual field.

Macular degeneration affects your central vision, but not your peripheral vision; thus it doesn't cause total blindness. Still, the loss of clear central vision — critical for reading, driving, recognizing people's faces and doing detail work — greatly affects your quality of life. In most cases the damage caused by macular degeneration can't be reversed, but early detection may help reduce the extent of vision loss.

The condition tends to develop as you get older, hence the "age-related" part of its name. Macular degeneration is the leading cause of severe vision loss in people age 50 and older.

Macular degeneration usually develops gradually and painlessly. The signs and symptoms of the disease may vary, depending on which of the two types of macular degeneration - wet or dry - you have.

Wet AMD occurs when abnormal blood vessels behind the retina start to grow under the macula. These new blood vessels tend to be very fragile and often leak blood and fluid. The blood and fluid raise the macula from its normal place at the back of the eye. Damage to the macula occurs rapidly.

With wet AMD, loss of central vision can occur quickly. Wet AMD is considered to be advanced AMD and is more severe than the dry form.

An early symptom of wet AMD is that straight lines appear wavy. If you notice this condition or other changes to your vision, contact your eye care professional at once. You need a comprehensive dilated eye exam.

Dry AMD occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye. As dry AMD gets worse, you may see a blurred spot in the center of your vision. Over time, as less of the macula functions, central vision in the affected eye can be lost gradually.

The most common symptom of dry AMD is slightly blurred vision. You may have difficulty recognizing faces. You may need more light for reading and other tasks. Dry AMD generally affects both eyes, but vision can be lost in one eye while the other eye seems unaffected. One of the most common early signs of dry AMD is drusen. Drusen are yellow deposits under the retina. They often are found in people over age 60. Your eye care professional can detect drusen during a comprehensive dilated eye exam.

Dry AMD has three stages, all of which may occur in one or both eyes:

• Early AMD. People with early AMD have either several small drusen or a few medium-sized drusen. At this stage, there are no symptoms and no vision loss.
• Intermediate AMD. People with intermediate AMD have either many medium-sized drusen or one or more large drusen. Some people see a blurred spot in the center of their vision. More light may be needed for reading and other tasks.
• Advanced Dry AMD. In addition to drusen, people with advanced dry AMD have a breakdown of light-sensitive cells and supporting tissue in the central retinal area. This breakdown can cause a blurred spot in the center of your vision. Over time, the blurred spot may get bigger and darker, taking more of your central vision. You may have difficulty reading or recognizing faces until they are very close to you.

If you have vision loss from dry AMD in one eye only, you may not notice any changes in your overall vision. With the other eye seeing clearly, you still can drive, read, and see fine details. You may notice changes in your vision only if AMD affects both eyes. If blurriness occurs in your vision, see an eye care professional for a comprehensive dilated eye exam.

There is no specific treatment for "dry" macular degeneration, although zinc supplementation may slow the progression of the disease. For the "wet" form of macular degeneration, laser photocoagulation (laser surgery to coagulate leaking choroidal blood vessels) may be useful in the early stages of the wet form of the disease. It involves the use of a thermal laser, which burns the abnormal, leaky blood vessels and stops them from spreading.

A newer treatment option for patients with "wet" macular degeneration is photodynamic therapy, which can be performed in a doctor's office. In this procedure a light-sensitive medication called Visudyne (verteporfin) is injected into a vein in the patient's arm. The drug circulates through the body to the eyes.

When a non-thermal laser is shone into the eyes, Visudyne produces a chemical reaction that destroys abnormal blood vessels. If the vessels re-grow, the procedure can be repeated. Photodynamic therapy is expensive and is not curative, but it can be successful in managing a particular area of leakage from the choroid through the RPE.

Your physician may recommend that you use an Amsler grid to discover possible new leaks before scarring occurs. Low-vision aids and therapy can be vital to the improvement of your quality of vision and life.