Overview
Treatment of Age Related Macular Degeneration (ARMD) is an important issue to 1.75 million Americans. It is the most common cause of severe, permanent visual loss in the Western world. The prevalence of ARMD increases with advancing age, and as many as 15% of U.S. citizens over 75 years old are affected. The U.S. population over 55 is expected to reach 88 million from its current 38 million by the year 2030, and the number of new ARMD cases could more than double.
The macula is the central portion of the retina that lines the inside of the back of the eye wall and acts as the film in the camera of the eye. It is functionally supported by a layer of Retinal pigment epithelial cells or (RPE layer) beneath it, which helps with its metabolism. Between this layer and the sclera is the blood vessel layer called the choriocapillaris.
The most common form of ARMD is the dry type, which usually causes slowly progressive vision loss. Drusen are deposits of waste by-products that can accumulate beneath the retina and can lead to further structural changes. Retinal thinning, pigment changes and loss of cells (atrophy) comprise other forms of dry ARMD.
Wet or exudative ARMD accounts for roughly 10% of ARMD cases, but it creates the majority of severe vision loss. This results from leakage of lipid or blood products from new blood vessel complexes (neovascularization) beneath the retina. This wet ARMD can cause abrupt changes in central vision.
Symptoms of Age Related Macular Degeneration
Symptoms of ARMD typically include blurring, distortion or darkening of central vision. The vision loss affects reading and recognizing objects. Bending or waviness to straight lines arises from fluid or blood accumulation beneath the retina, which moves the retinal light receptors out of their normal position. These symptoms can be subtle and occur in one eye at a time. Routine home monitoring of each eye separately using an Amsler grid can help to detect early changes in one eye that may be masked when both eyes are open.
Treatment for Age Related Macular Degeneration
Dry ARMD in moderate or severe forms can greatly benefit from supplements of antioxidant vitamins C, E, Beta Carotene and the mineral zinc. The National Eye Institiute AREDS study demonstrated a 25% reduction in progression of these forms of ARMD when taking the supplements. Smokers should not take extra Beta Carotene and should quit smoking.
The landscape for treatment of wet ARMD has dramatically changed during this decade. During the 1980s, laser treatment was defined by the Macular Photocoagulation Study and still is used to successfully treat certain lesions to limit vision loss. Certain lasers do cause heat injury not only to new blood vessel complexes but also to overlying retina, and thus some vision can be lost at the time of treatment.
Treatment Advances
Newer treatments of the wet forms of ARMD can actually lead to vision improvement without adjacent retinal tissue loss. Photo Dynamic Therapy or PDT involves the use of intravenous injection of light sensitive dye in the arm, which circulates to the eye and is acted upon by a special wavelength of light to seal off new blood vessel complexes without thermal damage. Steroid injection into the eye can be used in conjunction with PDT for a more lasting effect, but treatments may need to be repeated.
There now exists direct ocular injections of drugs such as Macugen and Lucentis that block proteins responsible for the creation of new blood vessel complexes and the worsening of their leakage of fluid or blood. These can be done in the office with low risk to the patient. More subtypes of wet ARMD are amenable to this type of treatment, and vision can not only be stabilized, but often recovered.
On the horizon, intravenous medications, macular translocation surgery, Strontium plaque therapy, and proton beam irradiation are being investigated to treat wet ARMD. Treatments such as laser to macular drusen and other nutritional supplements are being investigated for the treatment of dry ARMD.
Take Care of Your Eyes!
What can you do now? Have an annual dilated eye exam by your eye care provider. Follow the recommendations for future appointments and daily home monitoring of your vision in each eye separately. Modify your risk factors for ARMD by stopping smoking, avoiding excessive alcohol intake, and controlling your hypertension. And remember, wear sunglasses with Ultraviolet 400 protection while outdoors..
