Macular degeneration is a leading cause of blindness. Age-related macular degeneration 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.

The first sign of macular degeneration may be a need for more light when you do close-up work. Fine newsprint may become harder to read and street signs more difficult to recognize. Eventually you may notice that when you're looking at an object, what should be a smooth, straight line appears distorted or crooked. Gray or blank spots may mask the center of your visual field. The condition may progress rapidly, leading to severe vision loss in one or both eyes.

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.

Treatment

Currently there's no treatment for dry macular degeneration. But this doesn't mean you'll eventually lose all of your sight. Dry macular degeneration usually progresses slowly, so many people with this condition are able to live relatively normal, productive lives, especially if only one eye is affected.

Some treatment options are available for wet macular degeneration. But the success of the treatment — stopping further progress of the disease — depends on the location and the extent of the abnormal blood vessels, or choroidal neovascularization (CNV). In most cases the damage already caused by macular degeneration can't be reversed. The sooner CNV is detected, the better your chances are of treatment preserving what's left of your central vision.

Treatments for wet macular degeneration, all of which can be done as outpatient procedures, include:

• Photocoagulation. In photocoagulation your doctor uses a high-energy laser beam to create small burns in areas with abnormal blood vessels. The process can seal off and destroy the CNV that has developed under your macula. It can prevent further damage to the macula and halt continued vision loss. Only about 20 percent of people who have wet macular degeneration are candidates for this procedure. Whether it's right for you depends on the location and appearance of the CNV, the amount of blood that has leaked and the general health of your macula. Even if photocoagulation is a viable option for you, the results can be disappointing. Laser surgery to destroy the CNV is successful only about 50 percent of the time. And even successfully destroyed CNV has a tendency to recur. Repeat laser treatment may not be possible in such an event.

• If you noticed a dark or gray spot in or near your central vision before laser treatment, the procedure will make vision in that spot completely and permanently blank. With time you may not notice the blank spot any longer, especially when you use both eyes. And if you closely monitor your vision and have frequent follow-ups with your doctor, you're likely to retain more sight than if you had received no treatment at all. Photocoagulation is the only proven treatment for CNV when it's not located directly under the fovea at the center of your macula.

• Photodynamic therapy (PDT). This therapy is for treating CNV that's located directly under the fovea. The fovea lies at the center of your macula and in healthy eyes provides your sharpest vision. If conventional hot-laser surgery were used at this location, it would destroy all central vision. PDT increases your chances of preserving some of that vision.

• This procedure combines a cold laser and a light-sensitizing drug that's injected into your bloodstream. The drug concentrates in the CNV under the macula. When your doctor directs cold-laser light at the macula, the drug releases substances that close off the abnormal blood vessels without damaging the macula, and the CNV transforms into a thin scar. The overlying rods and cones are largely preserved, resulting in better vision than if you had had hot-laser surgery or no treatment at all. The therapy can be repeated if the CNV doesn't close or if it reopens after initial closure.

• The Food and Drug Administration has approved the drug verteporfin (Visudyne) for use in photodynamic therapy. Studies involving verteporfin demonstrate that over a 2-year period, multiple treatment sessions reduced vision loss for two-thirds of the people who had clearly defined CNV under the fovea. Though these results are promising, other long-term benefits are still under study. For example, further research will determine if this treatment also helps people who have poorly defined or hidden areas of CNV.

• Macular translocation surgery. Macular translocation surgery is an experimental treatment for wet macular degeneration. This surgery can be used if the abnormal blood vessels are located directly under the fovea. To start the procedure, your surgeon detaches the retina, shifts the fovea away from the CNV and relocates it over healthy tissue. When the CNV is exposed, the surgeon can then use a hot laser to destroy blood vessels without damaging the fovea. This surgery can be performed only if your vision loss is recent (usually within 1 to 3 months), the extent of CNV is limited and the tissue around the fovea is healthy.