There are two forms of age-related macular degeneration (AMD): dry – also known as non-exudative or non-neovascular AMD – and wet, also known as exudative or neovascular AMD.

• Dry AMD is the more common manifestation, accounting for about 90% of all cases. It develops slowly and is characterized by the death of critical cells in the macula, the central part of the retinal lining of the eye that allows you to see fine details. Dry AMD often causes mild vision loss. Many eyes with the dry type remain dry indefinitely. However, some will progress to the wet stage.
• Wet AMD is the less common variety, accounting for about 10% of all cases. However, this form is a much greater threat to central vision and accounts for about 90% of severe vision loss from AMD.

In the early stages, abnormal new blood vessels (subretinal or choroidal neovascularization) grow underneath the macula. These often leak fluid and blood, causing disturbance to central vision. Later, degeneration of the overlying light-sensitive retinal cells (photoreceptors) occurs. As the condition progresses, scar tissue can eventually form in the macula, causing a blind spot in the center of vision.

It is believed that age-related macular degeneration (AMD) is caused by the interaction of a multitude of factors, broadly grouped into several categories:

• Age is a major risk factor, with people over age 60 at greater risk than other age groups.
• Genetic factors also play a role. Scientists have identified several gene mutations that increase the risk of AMD and others that protect against it.
• Smoking cigarettes is a major risk factor, doubling, tripling, and in some studies, quadrupling the chances of developing the more advanced stages of AMD.
• Heart health, weight, and insufficient exercise: Some studies have shown an association between AMD and cardiovascular disease, obesity, and a lack of physical activity.
• Nutrition plays a role, with increased intake of certain items being protective, and others being potentially harmful.
• See more about prevention in the FAQs below.

Many patients with the earlier stages of age-related macular degeneration (AMD) in both eyes have no symptoms. A lot of patients with advanced stages of the disease in one eye but not in the other may also not be aware of any symptoms.

The only way to know for sure whether you have AMD is to have a thorough eye examination. This will involve measurement of your visual acuity (by reading the eye chart), examination of the front of the eye with a microscope, checking your eye pressure, and dilation of the pupils to allow for a complete view of the macula, the rest of the retina, and other structures at the back of the eye. Your eye care professional can determine if you need additional special testing, such as optical coherence tomography or fluorescein angiography.

As the disease progresses, some symptoms may appear, such as:

• Dry AMD often involves the gradual onset of slightly blurred vision. The most common symptom is a blurred spot in the center of vision. Over time, this blurred spot may become larger, and the sharpness of vision within the spot may decrease further. Affected individuals may need more light for reading or when completing other tasks. Over time, a dark or “empty” patch may appear in the center of vision as photoreceptor degeneration and scarring occur.
• Wet AMD may also cause blurred or fuzzy vision. In addition, straight lines, such as telephone poles, or the sides of buildings may appear wavy. A grid pattern, such as the tiles in your bathroom or an Amsler grid, may appear distorted. In contrast to dry AMD, the onset of symptoms in wet AMD is often sudden.

Patients with loss of center vision in both eyes notice difficulty seeing details such as print on a page or on TV or the facial features of people across the room. However, blindness is not an expected result, since the peripheral, or side, vision is typically unaffected.

Even with pronounced loss of center vision in both eyes, most patients with advanced age-related macular degeneration can see where they are walking and can do most things needed to take care of themselves. One notable exception is driving. For safety reasons, driving requires a certain degree of central vision in addition to peripheral vision, as determined by the laws in your state.

While there is no sure way to prevent age-related macular degeneration, certain lifestyle changes can lower your risk to some degree, including:

• Eat a healthy diet – one high in green leafy vegetables, fish, and nuts, as well as yellow, orange, and red vegetables
• Lower your intake of red meat and processed snack foods and baked goods, since the fats found in some of these may be harmful
• Don't smoke
• Watch your weight
• Control your blood pressure
• Exercise

The National Eye Institute's age-related eye disease study (AREDS) found that taking a specific high-dose formulation of antioxidants and zinc can significantly delay and possibly prevent the intermediate stage of dry age-related macular degeneration from progressing to the advanced stage in which vision loss occurs. The specific daily amounts of antioxidants and zinc used by the study researchers were 500 mg of vitamin C, 400 IU of vitamin E, 15 mg of beta carotene (often labeled as equivalent to 25,000 IU of vitamin A), 80 mg of zinc as zinc oxide, and 2 mg of copper as cupric oxide.

A follow-up to AREDS is evaluating the role of modifications to the original AREDS nutritional formula to determine if supplemental omega 3 long-chain fatty acids or supplemental lutein or zeaxanthin might be of benefit.

If you have age-related macular degeneration, ask your ophthalmologist what formulation of antioxidants is right for you. It may depend on the type of stage of macular degeneration you have, as well as your risk of developing the wet stage of age-related macular degeneration.

Note: Smokers should not be on any beta carotene supplements due to an increased risk of lung cancer. There are modifications to the AREDS formula that do not contain beta carotene that may be appropriate for smokers with age-related macular degeneration.

It is best to detect any progression from the dry stage of age-related macular degeneration (AMD) to the wet stage as soon as possible, since it improves the prognosis for treatment.

Early detection of changes requires not only regular eye examinations with dilation of the pupils, but also the participation of the patient in his or her own monitoring, using at-home vision testing with an Amsler grid and a reading test every week. If you notice any worsening of your vision in general or through the at-home tests, you should promptly schedule a retinal examination with your ophthalmologist. Seeing a retinal specialist, like those at Philadelphia Retina Associates, is the only way to be sure there has been no progression of dry AMD to the wet stage requiring treatment to preserve a patient’s vision.

There is not yet a treatment for the dry stage of age-related macular degeneration (AMD) that can reverse the condition or restore any lost vision. However, lifestyle changes and nutritional supplements noted in the prevention FAQs above can reduce the risk of dry AMD progressing, causing more significant vision loss.

For wet AMD, several approved treatments are available, including laser therapy, photodynamic therapy, and, more recently, drugs that can be injected into the eye after making it numb. The drugs available to date inhibit VEGF, a factor associated with encouraging the growth and leaks of abnormal blood vessels – the hallmark signs of wet AMD. Anti-VEGF drugs can stabilize vision in most cases and may even improve vision for some, although multiple injections for an indefinite period of time may be necessary.

Strategies under research to help diagnose, treat, and prevent age-related macular degeneration include:

• Transplanting healthy cells into a diseased retina
• Evaluating families with a history of AMD to understand the genetic and hereditary factors that may cause the disease
• Certain anti-inflammatory treatments for wet AMD
• Neuroprotective and stem cell technologies
• Augmenting anti-VEGF therapies with low-power laser or radiation therapy
• Gene-manipulative therapies

Low vision training is available for patients with persistently decreasing vision. Although low vision training is no cure for age-related macular degeneration, it may be helpful in performing essential tasks of daily living. Low vision rehabilitation involves using specific magnifying optical devices and lighting aids to assist in performing specific vision functions.