Age-Related Macular Degeneration
Age-Related Macular Degeneration (AMD) is a common disease of the retina in older patients. It is rare in patients less than 50 years of age, and becomes increasingly common after age 60. It is the most common cause of serious vision loss in older persons in the United States. It is less common in African Americans and more common in people of northern European heritage. The cause is hardening of the blood vessels in the central part of the retina. The retina is the part of the eye that works in the eye the way film works in a camera. Only the center of the retina which gives us sharp straight-ahead vision, called the macula, is involved in AMD. The rest of the retina, which gives us side vision, is never involved in AMD. The cause of the hardening is unknown. AMD does tend to run in families, but many people who have AMD do not have a family history. This may be because most people with AMD only have mild blurring at the center, and in past times the diagnosis may have not been made. Smoking is a major risk factor, and nutrition is also a risk factor.
There are two forms of AMD- wet AMD and dry AMD. Dry AMD is the earlier and usually milder form. Most persons with dry AMD have only mild blurring and dimming of the central vision, but some will progress to where reading and driving are impossible. The earliest symptoms are blurring and dimness in the central vision. About one in five persons with dry AMD will progress to wet AMD. Even persons with very mild dry form may progress to wet form of AMD. In the wet form of AMD the hardened and brittle blood vessels under the retina break down. Leaking of blood into the central retina (the macula) occurs. The usual symptom of progression to wet form is a new onset of distortion of vision. It is very important for patients in this situation to be seen urgently by an ophthalmologist, as laser treatment may be possible to seal the vessels and end the leaking from the broken vessel. Although this is not the kind of emergency where every second counts, patients with this type of change should be seen within a few days since laser treatment becomes less effective within a few weeks once the leaking blood causes scar tissue to form. Not all leaks can be treated with laser, but there are new treatments which use sensitizing dye to assist the laser, and some patients can be treated today who could not be treated in the past.
Although there is a lot to learn about why AMD happens and how to prevent and treat it, there are a number of things that you can do to help lower your risk of suffering vision loss from AMD:
- If you smoke, stop.
- Eat several portions of green leafy vegetables daily. Vitamin pills are not as effective.
- See your ophthalmologist for examination, especially if you have a family history of macular degeneration. If your ophthalmologist finds you are at risk, you may be given a home test called an Amsler Grid to use. This takes less than a minute a day and can help you detect wet AMD earlier and thus increase the chance of laser treatment being successful.
For patients with visual loss from AMD, it is important to remember that AMD is a self-limited disease. Although it can cause the loss of sharp vision so that reading and driving are impossible, it never causes complete blindness. Patients with AMD remain able to get around and perform most of their daily activities without assistance, and can retain much of their independence. There are a variety of special magnifiers which patients with AMD may be able to use to enable reading and other visual tasks to be done. Many full service eye care facilities, such as Boston Medical Center offer low vision rehabilitation services.
