Age-related macular degeneration (ARMD) is an inherited condition that affects the most sensitive part of the retina, the macula. Waste products known as drusen, form within the macula, “melting away” the rods and cones within the macula. Central vision is lost as a result of this process. ARMD is usually in both eyes. Damage to the macula may vary in severity. In the most advanced cases of ARMD, the loss of central vision will make reading and driving impossible. Patients with ARMD do not experience total vision loss. Many patients retain the use of their peripheral vision, therefore allowing them to function fairly well.
ARMD is classified as either dry or wet.
Dry ARMD causes a slower, less severe vision loss. The patient with dry ARMD may notice a gradual loss of central vision, with distortion and loss of letters in words being the first sign of change in vision. The patient may notice, as the disease progresses, the inability to read, do fine detail work, or even drive. The damage to the retina by dry ARMD may increase the patients chance of acquiring wet ARMD. There are no treatments for dry ARMD.
Wet ARMD causes a more rapid and severe vision loss and occurs in about 10 to 15% of ARMD patients. With wet ARMD, abnormal blood vessel formations, or sub retinal neovascularization (SRN) occur under the retina. This formation can break through the weakened retina, causing a collection of fluid, and in some cases blood. This formation causes a rapid loss of central vision. There is no cure for wet ARMD, however in the past there were laser treatments including Photodynamic Therapy (PDT), and Transpupillary Thermotherapy (TTT). These treatments depended on the type of leakage and the location of the leakage within the macula. The goal of the treatment was to stop the abnormal vessel formation, not to reverse the damage done by the vessels. Even with these treatments a certain amount of vision was lost and treatments may need to be repeated.
Over recent years there have been new developments in the treatment of wet ARMD. Medications are now available to shrink the SRN. The first to be FDA approved was Macugen in 2005 then Lucentis in 2006. Both are forms of antibodies to the vascular endothelial growth factor (VEGF) which is necessary for the growth of the abnormal blood vessels in wet ARMD. Macugen and Lucentis have not been compared in scientific clinical trials. The studies submitted to the FDA showed that patient that had the monthly injections for one year had a vision gain on average. Of course, since this is an average, this means that some patients had a vision gain and some patients remained the same and some lost vision. Another study had patients receiving monthly injections for three months and one injection every 3 months. Their vision initially improved during the monthly injections and then went back to where they started. This suggests that patients will need injections every month.
Testing is usually necessary to determine if the patient is eligible for treatment and which drug should be used. These drugs are administered in the office, through an injection into the eye. The eye is numbed but no other anesthesia is necessary. Most patients do not experience pain. These injections are administered every 4 to 6 weeks depending of the drug being used. It is important for patients to understand that these drugs are not a cure for wet ARMD.
A good way to test your central vision and monitor it for even the smallest changes is with an Amsler Grid. This is a square piece of graph paper with a dot in the center. When one eye is covered and the other eye focuses on the dot, the lines of the graph should look straight and even. Any distortion, blurring, discoloration, or other abnormality could be a sign of developing or progressing ARMD. Grid changes should be reported to your retina doctor as quickly as possible.
While there is nothing you can do to prevent ARMD, there are certain things which may affect its severity. Smoking and sun exposure have been shown to increase the progression of ARMD. A good diet enriched with leafy green vegetables and taking a multivitamin have been shown to slow down the progression of ARMD. The National Institute of Health released a 10 year study in fall 2001 showing a benefit to taking a vitamin formula with high doses of vitamins C, E, beta carotene, zinc and copper. This formula, known as the AREDS formula, should only be taken on the recommendation of your retina doctor, and should be approved by your medical physician. Due to recent reports of increased mortality with high doses of vitamin E, the American Academy of Ophthalmology issued the following statement:
“AREDS authors respond to study linking high-dose vitamin E to increased mortality risk”
The authors of the Age-Related Eye Disease Study (AREDS) are advising patients to continue taking 400 IU/day of vitamin E as part of the AREDS formulation. A recent meta-analysis of data from 19 studies involving nearly 136,000 people shows that daily doses of the vitamin above 400 IU are associated with an increased risk of death. However, the AREDS authors say this new analysis does not apply to patients at risk for advanced AMD, and there are no data in the study that prove it will increase their risk of death. AREDS researchers say it is unclear if the possible increased risk associated with very high doses (500 IU to 2000 IU) of vitamin E applies to people taking 400 IU. Furthermore, the AREDS study was included in the meta-analysis as one of three studies that evaluated intake of 400 IU. An increased risk of mortality was not found among those taking about 400 IU of vitamin E. The National Institutes of Health Office of Dietary Supplements has a fact sheet that summarizes the research on vitamin E and different chronic diseases. AREDS formula vitamins are nor recommended for patients who smoke, or have smoked in the recent past. Large doses of vitamin E have been shown to increase the incidence of lung cancer. For more information regarding vitamin therapy and macular degeneration, visit the National Eye Institutes website.