Age-Related Macular Degeneration
Age-related macular degeneration (AMD) is a progressive disease that affects a third of the population over age 70. Early symptoms include difficulty adjusting to lower light levels, blurring or distortion, and eventually reduction in vision. It targets a person’s central vision early, creating a blind spot in more advanced forms, making it difficult to perform normal daily activities such as driving, reading, and recognizing faces. Peripheral vision is normally preserved until late, and rarely does AMD result in complete blindness.
There are two major categories of AMD:
- Dry Macular Degeneration: This is the most common type (greater than 90 percent), caused by a thinning of the macula as cells begin to deteriorate with age. Additional risk factors include smoking, heredity, obesity, high blood pressure, and cardiovascular disease. Dry AMD is usually noticed in one eye with a gradual lessening of vision, however it is usually also present in the other eye as well. While symptoms may vary, they include blurred or hazy vision, the need for brighter lights when reading, straight lines appearing wavy or bent, difficulty recognizing faces, and a dark or empty spot in the central field of vision.
- Wet Macular Degeneration: This form affects only about 10 percent of people with AMD, but in the more advanced form of the disease results in earlier, more serious vision loss. It is marked by growth of abnormal blood vessels beneath the retina, where they leak fluid and blood disturbing the central part of the retina, the macula, which is critical to visual acuity. Wet AMD usually begins as dry AMD. The symptoms can be similar: reduced central vision in one or both eyes, straight lines appearing bent, and hazy vision overall. Wet AMD, however, can result in a more rapid deterioration than its dry form.
How is AMD Treated?
No treatment currently exists for dry macular degeneration. Early detection of the condition by your ophthalmologist, however, can result in a treatment program to slow its progress by taking vitamins and following a regimen of exercise and healthy foods.
For wet macular degeneration, first-line treatment consists of anti-VEGF (for vascular endothelial growth facto) agents. These agents have the ability to stabilize the deterioration of the disease, helping to preserve and in some cases actually improve your vision. The purpose of anti-VEGF injections is to stop the growth of abnormal blood vessels, which leak blood and fluids into the macula, resulting in swelling and impaired vision. Common anti-VEGF medicines used by retina specialists are:
- ranibizumab (Lucentis®)
- bevacizumab (Avastin®)
- afibercept (Eylea®)
Injection of these agents into the eye is performed using local anesthesia and is painless for the patient. Treatment requires a course of repeated injections to achieve the maximal benefit and maintain the improvement.
Photodynamic laser therapy (PDT) is another treatment approach useful for certain forms of wet macular degeneration. Treatment involves intravenous injection of a sensitizing drug, verteporfin (Visudyne), which is absorbed by the abnormal blood vessels in the retina. Activation of the drug with a non-damaging laser targets only these abnormal leaky vessels, which distort the vision.