What is age-related macular degeneration?
Age-related macular degeneration (ARMD) is the leading cause of vision loss among older Americans. The macula is the small area in the center of the retina that makes it possible to see details accurately from the center of the eye.
Macular degeneration results in blurred or distorted central vision or a central blind spot (a gap in the visual field) called a scotoma. When central vision becomes impaired, older people have difficulty recognizing faces and colors, driving a car, reading, or doing nearby manual labor, such as sewing or other manual labor.
Age-related macular degeneration results in gradual distortion and sometimes complete loss of central vision. Although age-related macular degeneration has the effect of creating a “blind spot” in the center of the visual field, vision outside the visual field is not affected. Macular degeneration alone does not result in total blindness.
People whose vision is affected by age-related macular degeneration are considered to have “low vision” or vision loss severe enough to interfere with the ability to perform daily activities and that cannot be corrected to normal by glasses or conventional glasses, contact lenses, medications, or surgery.
Types of macular degeneration
There are two types of macular degeneration: the dry or atropic type and the wet or haemorrhagic type. Dry ARMD is the most common form and is caused by atrophy of macula tissue. Yellowish deposits called drusen form under the macula and cause the macula to thin and dry out.
It is the less severe of the two types of ARMD. There is no known treatment that prevents macular degeneration or can return vision loss, and there is no specific medical treatment to restore vision.
The wet type of ARMD is its advanced stages causing the rapid growth of small blood vessels under the retina. The affected blood vessels lose blood and other fluid, which by forming scar tissue causes vision loss. This wet form can be treated with laser surgery, which can slow the rate of vision loss.
The National Eye Institute financially supports much of the medical research and clinical trials to improve the treatment of macular degeneration. Today, however, it is common for vision problems to recur over time after laser surgery.
Signs of macular degeneration
Macular degeneration is easy to detect. Symptoms include blurred areas on a page of printed text, straight lines that appear to curve or bend on a page, and dark or empty spaces that block the central area of vision. Typically, macular degeneration develops gradually over time and is often not detected in the early stages. There is no pain associated with ARMD.
Macular degeneration can be detected during an eye exam, so it is essential that people age 55 and older have their eyes examined once a year. ARMD can also be detected by a self-test using an Amsler Grid , which can be obtained from an ophthalmologist or an optometrist for use between exams.
The grid is a set of a horizontal line and a vertical line that creates small squares with a dot in the center of the grid. The person with macular degeneration will see the lines as curved, broken, blurred, or distorted when looking directly at the point in the center.
If this happens, make an appointment with an eye care specialist as soon as possible. However, this self-test is not a substitute for an annual eye exam.
How common is age-related macular degeneration?
Age-related macular degeneration is the leading cause of vision loss among older Americans 60 years of age and older, and its frequency increases significantly after age 65. It is most common among Caucasians (Caucasians or Europeans).
Today, one in twenty elderly citizens is affected by age-related macular degeneration, and as people live longer and the baby boom generation reaches retirement, the number of people with age-related macular degeneration is expected to exceed 6.3 million (Upshaw Institute for the Blind, 1998).
It is important to remember that macular degeneration alone does not cause total blindness. Indeed, peripheral or lateral vision remains intact. People with macular degeneration have what is referred to as “low vision,” meaning that the person still has some good usable vision and can learn to use it in the best way possible.
The person can learn a technique called eccentric gazing , which means using peripheral or lateral vision to see objects by moving the blind spot out of the center of vision.
There are ophthalmologists and optometrists with special training in low vision. Ask your eye care professional to refer you to a low vision specialist for a special type of eye exam called a low vision evaluation. The low vision specialist can help by prescribing and providing instruction in low vision optical devices, such as:
- hand-held or floor-standing amplifiers and high-intensity lamps for
- read printed pages or perform other nearby tasks,
- pocket telescopes for distance vision, such as reading a sign on the street or identifying the number of a nearby bus and
- a closed-circuit television (CCTV) that magnifies and projects
- printed materials on a television screen.
Low vision specialists also assist in identifying sources of financial assistance for the purchase of low vision devices that are not covered by Medicare or typical health care insurance plans. Recently Medicare and Medicaid have covered CCTV costs on a case-by-case basis, but not until the patient disputed several rejections.
Also available are software amplification packages for the computer screen-which enlarge the information on display.
Current technology makes it possible to adjust the image size and contrast of the information projected on the indicator screen.
Special light-filtering lenses are also available to help alleviate discomfort caused by glare and, in some cases, make the images appear sharper.
People with age-related macular degeneration can also make use of non-optical devices such as high-intensity lamps for guiding tasks with lights, scripts and signatures, and high-contrast markers.
An eye care professional can refer you to a service agency for the visually impaired. You can also contact your state’s rehabilitation agency serving the blind or visually impaired, which is usually located in the state agencies section on the back of a telephone book.
Vision-related rehabilitation services are provided by rehabilitation teachers, who work with people with low vision to preserve their independence, quality of life, and lifestyle. This is accomplished when they learn to perform daily tasks through adaptive devices and alternative methods that allow them to perform daily activities to the best of their available vision.
People with low vision can also learn to travel independently using a white cane through instruction from a specialist in orientation and mobility. They can also learn how to manage their homes, read, comply with their personal arrangement and perform a range of productive and meaningful activities, while continuing to live independently in their own homes.