Many Americans think loss of vision is a normal part of aging. Think again. The number one cause of vision loss is actually a disease called macular degeneration. This episode describes the disease and how you may be able to prevent it from compromising your vision.
What is macular degeneration?
Macular degeneration, also known as AMD (for age-related macular degeneration), is a chronic eye condition most common in people over 60. As a general rule, macular degeneration does not cause complete blindness. People with macular degeneration may lose their central vision, that is, their ability to see straight ahead, but retain their peripheral (side) vision. Macular degeneration progresses at different rates for every case, but wet macular degeneration progresses more quickly than dry.
How does the eye work?
To understand this, we need to understand how the eye and vision works. When light enters the eye, it passes through the cornea (a clear, rounded surface in front of the iris) and travels to the lens (a clear, flexible surface behind the pupil). The cornea and the lens refract (bend) the light, so that it will focus on the retina, the eye's inside back wall. The retina transforms the light into nerve signals (electrical impulses) that are sent to the brain. The result is vision.
The macula is in the center of the retina, and is therefore responsible for our central vision; that is, what we see when we look straight ahead. Damage to the macula affects the major part of our vision, our ability to read, drive, and do other daily activities.
There are two types of macular degeneration, dry vs. wet macular degeneration.
Dry macular degeneration
In dry macular degeneration, the cells of the macula begin to die. With fewer working cells in the macula, central vision becomes blurry; if the condition worsens, central vision can be lost. That means if you have dry macular degeneration, you may, at first, notice a blurry spot in the center of your vision. That spot can grow, then darken, and eventually you may no longer be able to see straight ahead.
But dry macular degeneration is painless and can progress so slowly that you barely notice it at first. Further, it can start and remain in one eye only, or it can progress to the second eye. If it affects one eye only, you may not notice any overall vision loss. However, in other cases, it can progress more quickly. In short, it's an unpredictable condition, and we don't know exactly what causes it. (Recent studies indicate there may be a genetic factor.)
Wet macular degeneration is caused by blood or fluid leaking from blood vessels into the macula. Usually these fluids come from new blood vessels that have grown behind the retina towards the macula. These new vessels are fragile and tear easily. The leaking fluids can quickly and severely damage cells in the macula, eventually causing blind spots in central vision.
The vast majority (about 80-90%) of all macular degeneration cases is the dry form, yet it causes only about 10% of blindness from macular degeneration. The reverse is true for wet macular degeneration; only about 10-20% of cases are the wet form, but they cause about 90% of blindness from macular degeneration.
Although dry macular degeneration does not necessarily turn into the wet form, almost all cases of the wet form do begin as the dry. Further, because it can cause rapid and severe damage, wet macular degeneration is considered an advanced stage of the disease. (More information about the stages of macular degeneration.)
Causes of macular degeneration
Although the causes of macular degeneration remain uncertain, we do know what the major risk factors are. (Risk factors are things that increase your chance of getting a condition or disease.) They include:
- Age. Although macular degeneration can happen earlier, people over 60 have a much higher chance of developing it.
- Race. Caucasians have a higher chance of developing it than African-Americans.
- Family history. People with a family history of macular degeneration have a higher chance of developing it.
- Gender. Women have a higher chance of developing it than men.
Other, less certain risk factors (things that may be risk factors but are not completely proven) include:
- Low levels of certain nutrients, including minerals such as zinc and antioxidant vitamins, such as A, C and E
- High levels of cholesterol
- High blood pressure
- Eye color. People with light-colored eyes seem to have a higher chance of developing macular degeneration than those with darker eyes.
- Long-term exposure to ultraviolet light (sunlight)
- Cardiovascular diseases
- The retina, the eyes inside back wall, transforms light into nerve signals that are sent to the brain, creating vision.
- The macula is in the center of the retina and allows us to see straight ahead.
- Degeneration (break down and death) of cells in the macula can happen at any age, but is most common in people over 60.
- Macular degeneration is also known as AMD (age-related macular degeneration).
- There are two types of macular degeneration, dry and wet. Dry has three stages (early, intermediate, and advanced). Wet is considered advanced macular degeneration and is more serious because it tends to progress more quickly.
- Early symptoms of dry macular degeneration include slightly blurred vision, need for more light for reading, and difficulty recognizing faces.
- A symptom of more advanced dry macular degeneration is seeing blurry, hazy or dark spot in the center of your vision.
- Early signs of wet macular degeneration include straight lines appearing wavy and other visual distortions.
- Smoking is a major risk factor for macular degeneration.
- Currently, there is no treatment for early dry macular degeneration.
- There are several effective treatments for wet macular degeneration, including laser surgery and drug treatments.
Ask Your DoctorThis list of questions is a good starting point for discussion with your doctor. However, it is not a comprehensive list.
- I've noticed these symptoms: list them
- What medical tests do I need to get an accurate diagnosis?
- What type of macular degeneration do I have?
If you have dry macular degeneration:
- What stage do I have?
- How severe is it? Do I have extensive vision loss?
- What changes in my vision should I expect in the future?
- How fast is the macular degeneration progressing?
If the macular degeneration is confined to one eye only:
- Are there indications that the disease is affecting my other eye?
- What symptoms should I watch out for?
- Should I use an Amsler grid at home, and how do I use it?
- What medical treatments are available to help me?
- What surgical treatments are available to help me?
- Do I need to change my glasses?
- What can I do to protect or prolong my vision?
- Should I be taking dietary supplements (such as antioxidant vitamins and minerals)? Who can recommend a helpful program?
- What lifestyle changes should I make? Who can give me
- A new diet
- An exercise program
- Help in stopping smoking?
If your vision can't be helped:
- Can you recommend a low vision specialist?
- Can you recommend agencies to call for help with vision rehabilitation and/or adapting to low vision?
Any change in vision is significant. The earlier you diagnose a disease and, if treatment is indicated, the earlier you can begin treatment, the better.
Three kinds of specialists provide different levels of eye care. It's important to understand the differences between them.
- Ophthalmologists are MDs (doctors of medicine) with advanced training in eye conditions (just as, for example, a cardiologist has advanced training in heart conditions). As medical doctors, ophthalmologists are legally allowed to diagnose eye conditions and diseases, prescribe medications, and do eye surgery.
- Optometrists have an OD (doctor of optometry) degree, but they have not gone to traditional medical school and are not MDs. Normally, they test and evaluate vision, diagnose some eye conditions, prescribe glasses and contact lenses, and make referrals to ophthalmologists for more serious conditions. Some states may allow them to prescribe some medicines, but they do not perform surgeries.
- Opticians are essentially eyeglass makers. They fill prescriptions for eyeglasses, making the lenses and assembling and fitting the glasses. Some states allow them also to sell and fit contact lenses. However, they don't provide direct patient care, eye exams or prescriptions for glasses.
If you notice symptoms of macular degeneration, you should see an ophthalmologist.
What are the symptoms? The most obvious is any change in your vision. Specifically, early signs of dry macular degeneration include:
- Slightly blurred or hazy vision
- Colors seem less intense
- Needing more light for reading and other everyday activities
- Difficulty recognizing faces
Early signs of wet macular degeneration include:
- Straight lines appear wavy
- Other visual distortions (such as objects seeming further away than they are)
- Fuzzy, hazy, or shadowy area (blind spot) in central vision
Perhaps the most frightening symptom of macular degeneration is hallucinations. They're not present in all cases, but they're common enough to have been given a name - Charles Bonnet syndrome. People sometimes see weird patterns, strange geometric shapes, or bizarre faces or animals. Because people don't realize they're a symptom of an eye condition, not mental illness, they may not talk about them to their doctor. Therefore, the doctor doesn't have important information that can help with diagnosis and treatment. Never be afraid to discuss anything with your doctor; your health may depend on it.
- Dry macular degeneration generally progresses slowly; wet macular degeneration generally progresses quickly
- Both forms are painless
- Both forms usually affect both eyes but can start and remain in one eye only. If it remains in one eye, you may not notice any symptoms for a long time
An ophthalmologist diagnoses macular degeneration by giving you a thorough eye exam. This exam may include:
Visual acuity test: you read an eye chart to measure your ability to see at various distances
Dilated eye exam: the doctor puts drops in your eyes to dilate (expand or widen) the pupils, then uses special magnifying lenses to look inside them and examine the retina and optic nerve
Tonometry: the doctor uses a device to measure pressure inside the eye
Amsler grid test: you look at a pattern of lines with a dot in the center; if the lines in the grid appear wavy or some seem to be missing, that may be a sign of macular degeneration
Fluorescein angiography: the doctor injects a special dye into your arm; as the dye passes through the blood vessels in your eye, pictures are taken that can reveal leaking blood vessels; the pictures are called fluorescein angiograms.
Optical Coherence Tomography or OCT: the doctor uses a device that emits rays of light to measure the thickness of your retina; a thickening or swelling retina can indicate the build up of fluid, possibly caused by wet macular degeneration. OCT is often used to help check the retina's reaction to treatments for macular degeneration
The eye exam may reveal the presence of "drusen." Drusen are yellow, fatty deposits under the retina. Their presence may be an indication of dry macular degeneration.
If you do have dry macular degeneration, the eye exam will help determine its stage. Dry macular degeneration has three stages: early, intermediate, and advanced. They can be described as follows:
Early: you have several small drusen or a few medium-sized drusen, but no symptoms and no vision loss
Intermediate: you have many medium-sized drusen or one or more large drusen and you may have some symptoms, such as seeing a blurred spot in the center of your vision or needing more light to read
Advanced: you have drusen and other symptoms and the exam reveals the breakdown of light-sensitive cells and supporting tissue in the macula
Wet macular degeneration has no stages; it's considered an advanced stage of the disease.
Key Point 2
Timely treatment of macular degeneration is essential to preserve vision.
Research in macular degeneration is quite intense, and treatments are available today that were not available ten or even five years ago. Currently (as of mid-2007), treatment can dramatically slow down vision loss. And, in a few years we may see startling innovations.
Today, there are several treatments for wet macular degeneration; all are outpatient procedures, done in a doctor's office or eye clinic. They include:
- Laser surgery (sometimes called photocoagulation). The doctor aims a high-energy laser beam at the eye that destroys the fragile new blood vessels under the macula (leakage from these vessels causes wet macular degeneration). This is a proven treatment and can be very successful, but:
- Only a small percentage of wet macular degeneration patients are good candidates for this procedure.
- Because new blood vessels can form and grow under the macula after the surgery, repeat treatments may be necessary.
- Despite the procedure, vision loss may continue.
- Cold laser or photodynamic therapy. The doctor injects a drug, verteporfin (trade name Visudyne), into the arm, which is absorbed by the blood vessels causing the macular degeneration. Then the doctor shines a "cold laser" light into the eye for 83 seconds; this activates the drug, which destroys the leaking blood vessels.
- Patients usually need repeat treatments
- Patients must avoid direct sunlight or bright indoor light for five days after treatment
- Drug injection therapy. Known as anti-VEGF (vascular endothelial growth factor) therapy and used to treat wet macular degeneration, the doctor injects drugs directly into the eye. Drugs currently used include:
- Macugen (generic name: pegaptanib)
- Lucentis (generic name: ranibizumab)
- Avastin (generic name: bevacizumab)
Today, there are no treatments that effectively combat advanced dry macular degeneration. However, there is now research into treating dry macular degeneration by using laser surgery (photocoagulation, described above) to remove and prevent the growth of drusen.
Other ongoing research into possible treatments include studies of:
- Steroids and other anti-inflammatory drugs
- Transplanting healthy cells into a diseased retina
- Devices that could be implanted into the eye to improve vision
- Rheopheresis, the technique of removing blood from the body, filtering it to remove harmful substances (in this case, those that contribute to macular degeneration), then returning it to the body
There are also ongoing studies of families with a history of macular generation that are looking for possible genetic and hereditary factors that may cause the disease.
Of course, the old idea that "an ounce of prevention is worth a pound of cure" holds true here as well. While you can't stop yourself from becoming older (the major risk factor for macular degeneration), you can take other preventative steps. Specifically, the National Eye Institute's Age-Related Eye Disease Study (AREDS) suggests that taking certain antioxidant vitamins and minerals may reduce the risk of developing the disease or delay and even prevent earlier stages from becoming advanced.
Antioxidants are nutrients and other substances that protect cells in the body from the damage caused by "oxygen free radicals." These are molecules that seek to become oxidized, a process that harms body tissues and has been linked to many diseases, including stroke, heart disease, and cancer. Antioxidants are found naturally in food but are also available as dietary supplements.
Important antioxidants include:
- Vitamins A, C, E, and beta-carotene (found in carrots)
- Lycopene (found in tomatoes)
- Flavonoids (found in ginkgo biloba, black cherries, blackberries, bilberries, and blueberries)
- Quericetin - a specialized flavonoid found in apples, onions, tea, and red wine
- Coenzyme Q10 - a vitamin-like substance found in soy, whole grains, mackerel, and chicken
- Trace minerals, such as selenium, zinc, manganese, and copper also appear to help cells fight off free radical damage.
The National Eye Institute says people who are at high risk for developing advanced macular degeneration should consider taking the so-called "AREDS formulation." They define "high risk" as having either intermediate dry macular degeneration in one or both eyes or advanced macular degeneration, dry or wet, in one eye.
The AREDS formulation, a supplement to your regular diet, consists of:
500 milligrams of vitamin C
400 International Units of vitamin E
15 milligrams of beta-carotene
80 milligrams of zinc as zinc oxide
2 milligrams of copper as cupric oxide
The Institute adds that their study found no evidence that the formulation helps those with early stage dry macular degeneration. However, eating a healthy diet, full of leafy green vegetables, fruits, and other vegetables, is always excellent for your health in general. Some studies suggest that eating fish is also good for preventing macular degeneration; others are looking at the possible positive effects of egg yolks, corn and spinach (which contain the nutrients lutein and zeaxanthin).
Other specific preventative measures include:
- Wearing sunglasses to block harmful ultraviolet light (both "ultraviolet A (UVA)" and "ultraviolet B (UVB)"
- Having regular eye exams (every two to four years if you're over 40; every one to two years if you're over 65; more often if you have a family history of macular degeneration)
If you already have early stage dry macular degeneration, get an Amsler grid from your eye doctor and learn how to use it at home to see if the disease is worsening. (An Amsler grid is a pattern of lines used to diagnose macular degeneration.) For more information about it, go to Key Point 1.)
Finally, there are preventive measures that are familiar pieces of advice for improving your health in general:
- Stop smoking – or don't start
- Get more exercise
- Watch your weight
- Watch your blood pressure.
Yes, they're familiar, but don't let familiarity breed contempt. Each of them can truly be a lifesaver, as well as an eye-saver.
Key Point 3
If you are experiencing low vision, there are steps you can take to maintain and restore function in your life so you can live independently.
Human beings are remarkably adaptable. Having low vision (poor vision that can't be improved with glasses) is nothing to be wished for, but it need not stop you from enjoying life as much as possible. There are many organizations and agencies that offer services to people with low vision, including counseling, training, and help. For information about some of them, go to Resources. Your eye doctor can also refer you to them, and to specialists in low vision care.
Among the many helpful tools and devices available to people with low vision are:
- A variety of magnifiers that make print bigger and easier to read
- Some are hand held; others are worn like glasses
- Using them takes practice, but it's worth the effort
- Closed circuit television systems (CCTVS) consisting of small video cameras and special monitors. They can enlarge print and handwritten items but are quite costly.
- Telescopes and telescopic lenses for seeing distant objects more easily
- Clocks, watches, and timers with larger numbers for easier reading
- Special lamps that offer brighter light for reading and close work
- Large print books, newspapers, and magazines
- Telephones with larger numbers, and telephone attachments in large-print type
- Magnified makeup mirrors
- Audio (talking) books
- Talking calculators and clocks
- Talking computers (computers with screen reading software), computers with large screens, and other devices and software that make using computers and accessing the internet easier
- Printers that use large type faces
- Absorptive lenses that can be worn over regular glasses and increase safety and comfort by controlling how much light reaches the eye, blocking out harmful ultraviolet light, reducing glare, increasing contrast, assisting in the transition between light and dark areas
There are also many things you can do for yourself and ways to arrange your surroundings that will help you adapt to low vision. For example:
- If you can still drive legally, and choose to, do so with extra caution and avoid driving at night, in heavy traffic or in bad weather
- If you need help traveling, get it; that's what family and friends are for. Also:
- Learn the public transportation system in your area
- Learn about local vans, shuttles, volunteer driving networks, ride shares, and other services for people with impaired vision
- Ask utilities and other businesses and organizations to send bills (and other mail) printed in large type
- Organize your home for ease and safety:
- Mark appliances so you can "read them" by touching them
- Keep keys, money, medication, etc. in the same place, so you know where to find them
- Organize your closets, shelves, kitchen cabinets, etc. so you know where things are. You can even arrange things on a plate when eating, so you know the "fish is at ten o'clock, vegetables at five o'clock, etc."
- Remove things you might trip over, such as throw rugs, and other hazards
You'll find a long, extremely helpful guide to organizing every room in your house plus useful tips about travel, hobbies, and other lifestyle issues at AMD Alliance International
Perhaps most important of all, at least for your mood and psychological health, is to stay socially active. If you're frustrated because you can't recognize people, then simply be direct and honest and ask people to greet you and identify themselves, so you can greet them back and have a normal conversation with them.
Remember that macular degeneration is not affected by how much you use your eyes. So don't be afraid to use them for reading, going to movies, and other activities you enjoy.
Conduct an off-site search for Macular Degeneration information from MedlinePlus. These up-to-date search results are based on search terms specific to Second OpinionKey Points.