Age-related macular degeneration (AMRD), is the ageing of the outermost layer of the retina, mainly found in adults over the age of fifty. At its most devastating, ARMD results in severe visual impairment and often overwhelming challenges to the quality of life.
It is the cause of severe visual impairment in at least 2 percent of Americans over the age sixty-five. The macula is usually responsible for central vision, including functions such as reading and visual acuity. Made largely of cones, it’s also important for colour vision. People with the macular disease often have a poor central vision but normal side vision primarily since their peripheral retina remains healthy.
There is no universally accepted definition of age-related macular degeneration. However, most eye specialists agree that ARMD includes certain changes in the retinal cells and Bruch’s membrane of the macula. All of these changes are seen in most older individuals. but they may be found in sonic people as early as their forties and fifties.
Types of Age-related Macular Degeneration
There are two basic kinds of ARMD:
The Dry Form
A Dry or atrophic form of ARMD features slow progressive, degenerative changes in the retinal cells, Bruch’s membrane and the choroid. Many eye researchers consider this form of ARMD as an exaggerated form of the normal ageing process of the retinal pigment epithelial cells. Normally, the onset of deterioration of retinal cells leads to a vicious cycle, starting with the worsening of photoreceptors. As photoreceptors degenerate, they release debris, which builds up beneath the retinal pigment epithelium, causing further cell malfunction and loss. Eventually, this process may cause loss of vision by means of a slow degenerative process.
The Wet Form
The wet, or exudative, form of ARMD is a faster, more aggressive process that can have a much greater impact on vision. Though uncommon (only about 2% of ARMD patients), its impact can be much more serious, often leading to more than 50% of the loss of vision caused by ARMD.
Unfortunately, both the dry and wet forms of ARMD can occur in the same person and in the same eye.
Risk Factors
ARMD affects an estimated 3.5 million older Americans. Studies by the National Eye Institute (an arm of the National Institutes of Health) have shown that ARMD (mostly the wet form) is the cause of more than sixteen thousand new cases of legal blindness each year. Unlike cataracts, which cause a reversible form of vision loss, the damage caused by age-related macular degeneration is irreversible. Comparatively, even glaucoma and diabetic retinopathy, two other well-known causes of serious vision problems in people over age fifty, are much more treatable.
As far as ARMD is concerned, the most obvious risk factor is age. Further, the disease is more common in women than men and people with blue eyes, especially Caucasians, seem more susceptible. Heredity also seems to be a major risk factor and it is better to have an eye examination if you have a family history of age-related macular degeneration. Other risk factors include cigarette smoking, cardiovascular diseases, high blood pressure, excess exposure to sunlight etc.
Prevention: Can proper nutrition make a difference?
Much speculation prevails regarding the preventive effects of vitamin supplements on problems such as macular degeneration and cataracts. However, dietary deficiencies in vitamins A and E can cause the retina to degenerate. Vitamin C may also have a protective effect against sun damage to retinas. Nevertheless, research has shown some link between age-related macular degeneration and antioxidants such as vitamin E, vitamin C and beta-carotene.
Signs and Symptoms of ARMD
Age-related macular degeneration, like many other eye disorders, is a dangerously silent, stealthy process. By themselves, retinal changes usually don’t affect vision and are rarely noticeable. However, central reading vision does become affected over time as these changes become more severe. For many people, the first signs of trouble may be that the lines of a book or patterns of clothing may start to look crooked or wavy, usually more pronounced in one eye than the other. Later, reading becomes particularly difficult as letters and words become distorted. Other people notice that their eyes have trouble adjusting from bright sunshine to a dimly lit room. People with advanced age-related macular degeneration often need a few minutes to adapt to this change in lighting.
Importance of Early Detection and Regular Monitoring
If you’ve been diagnosed with age-related macular degeneration, it’s essential that your vision is monitored regularly. Your eye examinations should include a carefully prescribed retinal evaluation by an ophthalmologist who is very familiar with this disorder and its clinical stages, at a regular interval of every three to four months.
Many eye doctors advocate home tests of visual acuity which function as a do-it-yourself means of monitoring the progress of macular degeneration. You should test each eye separately and as often as every day if you’re a person at high risk for wet ARMD. Be sure to report anything unusual to your eye doctor immediately. If detected early enough, ARMD may be amenable to treatment.
Although there is no treatment for the dry form of ARMD once it reached an advanced stage, lasers can sometimes be used successfully to treat the new membranes that develop in the wet form. In such circumstances, early detection and treatment may mean the difference between useful sight and legal blindness.
Treating ARMD
It is important to note that a vast majority of eyes with macular degeneration- dry or wet, can’t be helped by any form of treatment. However, some measures which may help in subsiding effects include-
Lasers – Although laser treatment has been shown to be successful for patients with the wet form of macular degeneration, few people (about 10%) are considered good candidates for the procedure. Further, laser treatment can be effective for some, though but not all.
Surgery – Surgical approaches to age-related macular degeneration are often less successful. Some ophthalmologists have also tried retinal transplants, but two basic complications arise- rejection of the corneal transplant by the eye and inability to regenerate retinal cells after replacement in the eye.
Other Treatments – Another exciting medical treatment include the use of drugs, dye-assisted photocoagulation and radiation therapy. These techniques may enhance doctors’ ability to more accurately and precisely treat sub-retinal neovascular membranes.
There’s no good way to measure the true impact of age-related macular degeneration and the burdens it often creates for family, friends, and society. But even though there’s no cure yet, there are many things patients can do to retain independence and quality of life. Use of visual aids, glasses, magnifiers, low-vision devices, and large-print materials may prove to be beneficial to ARMD patients.
Dr. Babak Shabatian, MD, is an ophthalmologist and founder and director of Cali Eye and Laser Institute, Torrance, CA. He has performed thousands of procedures with excellent and predictable results. He is frequently invited to lecture on topics of refractive and advance cataract surgery.