Age-Related Macular Degeneration (AMD) is the leading cause of vision loss among Americans over the age of 60. AMD is a disease that occurs in the retina, the layer of tissue at the back of the eye that changes light and images into nerve signals that are sent to the brain. The macula is the center part of the retina which makes our vision sharper and more detailed. AMD commonly leads to a loss of central vision which is important for daily tasks such as reading and driving. Peripheral vision usually remains intact.
Macular degeneration occurs when there is age-related damage to the macula which can ultimately lead to thinning of retinal tissue or abnormal blood vessel growth. There are two forms of macular degeneration, dry (atrophic) and wet (exudative):
Dry Macular Degeneration:
- Blood vessels under the macula become thin and brittle.
- Small yellow deposits, called drusen, form under the macula.
- As drusen increase in size and number, a blurred and/or dim spot in the central line of vision develops.
Wet Macular Degeneration:
- When brittle vessels break down, new abnormal and very fragile blood vessels grow under the macula, called choroidal neovascularization.
- These vessels leak blood and fluid, which leads to damage of the macula.
- Vision loss may be rapid and severe.
- Occurs in only about 10% of people with macular degeneration; however this form causes most of the vision loss associated with macular degeneration.
Although the exact cause of AMD is unknown, both genetic and environmental factors play a role. The same things that put you at risk for heart disease and stroke also put you at risk for AMD: high blood pressure, high cholesterol, obesity and smoking. Low levels of nutrients and minerals such as zinc and vitamins may also increase the risk of AMD. There are a few risk factors that are beyond your control:
People aged 60 and above have a higher risk.
If you have immediate family members with AMD, you have a higher risk.
AMD is more common in Caucasians.
The physicians at Newsom Eye can diagnose AMD during your eye examination. It is important that all adults over the age of 50 have an annual dilated eye exam to screen for AMD as visual symptoms may not appear until further along in the disease.
Symptoms for AMD can vary from person to person. The following are the most common:
- Words on a page look blurred
- A dark or empty area appears in the center of vision
- Straight lines look distorted
For dry AMD there is no treatment currently available. However, taking high levels of antioxidant vitamins has been shown to slow progression of the disease. The recommended formula of vitamins is the Age-Related Eye Disease Study (AREDS) formula, which is available over-the-counter. Because dry AMD can convert to wet AMD at any time, all patients with dry AMD should perform daily Amsler grid testing to check for any distortion in their central vision. If distortion or dark/blurred spots appear in either eye, bleeding is likely and a retina specialist should be contacted immediately. Wet AMD treatments include laser and/or injections to reduce bleeding. As treatment is much more effective for early stages of wet AMD, self-screening for visual changes and regular follow-up with your retina specialist is critical.