AMD is a common eye disease associated with aging that gradually destroys sharp, central vision. Central vision is needed for seeing objects clearly and for common daily tasks such as reading and driving. In some people, AMD advances so slowly that it will have little effect on their vision as they age. But in others, the disease progresses faster and may lead to a loss of vision in one or both eyes.

Types
AMD occurs in two forms. Wet (vascular) and dry (atrophic). Although only ten percent of all people with AMD have wet AMD, it is responsible for the vast majority of severe, AMD-related vision losses. As dry AMD worsens, new blood vessels may begin to grow and cause wet AMD. Because these new blood vessels tend to be very fragile, they will often leak blood and fluid under the macula. This causes rapid damage to the macula that can lead to the loss of central vision in a short period of time.

Dry AMD affects the other ninety percent of cases. The earliest sign of dry AMD is the development of waste material deposits, called drusen, that appear as tiny orange or yellow dots among the retinal pigment epithelial cells. These deposits are initially tiny and few in number, but they may grow larger and become more numerous. Scientists are still not sure what causes dry AMD. Studies suggest that an area of the retina becomes diseased, leading to the slow breakdown of the light-sensing cells in the macula and a gradual loss of central vision.

Causes
Most cases of macular degeneration are age-related, meaning older people are more likely to have it. Risk factors include: being white or female, having a family member with AMD, smoking, high blood pressure, farsightedness and obesity. The exact causes are still unknown. Because the condition often runs in families, AMD may be hereditary.

Symptoms

The main symptom is central vision loss, which is gradual in dry AMD and sudden in wet AMD. Other symptoms include blurry or fuzzy vision, dark spots in the center of vision, difficulty reading or performing detail work; and seeing straight lines as wavy or bent.

Treatments
No treatment currently exists for dry AMD. Progression of dry macular degeneration can be slowed by taking high doses of the vitamins A, C and E, and the minerals zinc and copper. Patients should discuss these vitamin and mineral supplement treatment options with their primary care doctor. Research is under way to identify other vitamin and mineral combinations that may be viable treatments for dry macular degeneration.

There are two FDA approved treatments available for wet macular degeneration:

Anti-angiogenic therapy (injectable drug treatment) and Photocoagulation (laser surgery).

Injectable drug treatments that directly target the growing blood vessels in patients with wet macular degeneration. After the ophthalmologist numbs the eye with an anesthetic, the drug ranibizumab (Lucentis®) or bevacizumab (Avastin®) is injected into the affected eye. The medicine stops or slows the blood vessels from growing, leaking and bleeding.

The treatment is given every four to six weeks to prevent the blood vessels from causing more vision loss. This therapy causes less damage to the retina than laser treatments. The most common side effect after receiving an injection is redness and scratchiness in the eyeball.

Photocoagulation (laser surgery)

Photocoagulation uses a high-energy laser beam to create small burns in areas of the retina that have abnormal blood vessels. This treatment is used when the abnormal blood vessels are not yet under the area of central vision (fovea). Because it is uncommon for the blood vessels to spare the fovea, only a small number of patients are candidates for the procedure.

The doctor determines who may benefit from the treatment based on the location and appearance of the blood vessels, the amount of blood leakage, and the overall health of the macula. The laser may destroy some surrounding healthy eye tissue and some vision. New blood vessels also may develop after this treatment.

Photodynamic therapy

In this treatment, the drug verteporfin (Visudyne®) is injected into the bloodstream. The drug concentrates in the abnormal blood vessels under the macula. The doctor then focuses cold-laser light at the macula, which activates the drug and leads to the closing off of abnormal vessels without damaging the macula. Photodynamic therapy is commonly performed as a combination therapy with other treatments.

The location of the abnormal blood vessels often determines which treatment is selected. The macula is the central portion of the retina responsible for central vision, and the fovea, responsible for the sharpest vision, is directly in the center of the macula. If the abnormal vessels are located directly under the fovea, hot laser treatment (photocoagulation) would damage the fovea and decrease central vision. In these cases, photodynamic therapy may be an excellent option.

Teresa Lui, O.D.       Palo Alto Optometrist         Optical Boutique           650-321-9525          info@drteresalui.com