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U.S. Food and
Drug Administration
FDA Consumer magazine
March-April 2002
Table
of Contents
by Michelle Meadows
Sometimes eye diseases occur with the natural aging process. Other times, they run in families, in the same way that cancer or heart disease might. Diseases and conditions such as diabetes and high blood pressure also increase the risk for eye problems. The leading causes of irreversible blindness--glaucoma, diabetic retinopathy, and macular degeneration--tend to come on silently, without pain or other symptoms in the earliest stages. The later an eye problem is diagnosed, the harder it becomes to treat. In some cases, any vision that has slipped away may be gone forever.
Experts say that skipping regular and thorough eye exams is chief among the barriers to early detection. It's important to have your eyes regularly checked through dilated pupils so doctors can get a good three-dimensional view of the optic nerve and retina. For a dilated exam, an eye specialist places drops in the eye to enlarge the pupils. "Without dilating the eye, it's like looking inside a room through a keyhole instead of an open door," according to George Blankenship, M.D., immediate past president of the American Academy of Ophthalmology (AAO).
Also problematic is the tendency to ignore symptoms when they do present themselves, says Lee R. Duffner, M.D., an ophthalmologist in Hollywood, Fla. "It's not uncommon to see patients who say they've been having eye problems for a whole year before coming in to get checked--usually because of a spouse or other relative who encouraged them to come in."
Here's a look at four eye diseases you can't afford to miss.
It's not known why, but people with glaucoma typically experience an imbalance in eye fluid production and drainage. Fluid that normally flows in and out of the eye drains too slowly. As that fluid builds up, pressure in the eyeball increases and becomes abnormally high, a condition that can damage the optic nerve, the retina, or other parts of the eye.
It's important to note that there are also patients with glaucoma who actually have what would be considered normal eye pressure, says Sheryl Berman, M.D., a medical officer in the Food and Drug Administration's division of ophthalmic and ear, nose, and throat devices. "This is why it is so critical to have dilated examinations, since routine pressure screening would miss the diagnosis of glaucoma in these eyes." For these people, there are other factors at play that may lead to optic nerve damage.
If glaucoma is left untreated, blindness is likely. The most common form of glaucoma is primary open-angle glaucoma, also known as chronic glaucoma. Nearly 3 million Americans have glaucoma, according to the National Eye Institute (NEI), and about half do not know it. That's because glaucoma is a silent stealer of sight; there are usually no symptoms in the early stages. As the disease progresses, people with glaucoma may notice their side (peripheral) vision failing. But by this time, the disease is usually quite advanced and the damage is irreversible. Once vision is lost, it can't be restored. Glaucoma usually affects both eyes, one shortly after the other.
Ida Miggins, 52, a computer specialist from Takoma Park, Md., says she learned she had glaucoma three years ago by chance. She hadn't had an eye exam since childhood and hadn't noticed any vision problems. "I was actually taking my mother to her eye appointment, and the doctor suggested that I be checked too," says Miggins. The doctor diagnosed glaucoma in both eyes.
Early detection is the best way to control glaucoma and prevent major vision loss. Elevated pressure in the eye is the major risk factor for glaucoma. Other risk factors associated with the disease include having high blood pressure, diabetes, and certain diseases that affect blood vessels. A family history of the disease, aging, and African ancestry also increase your risk for glaucoma.
Studies have shown that for unknown reasons, glaucoma presents at an earlier age in blacks, is five times more likely to occur in blacks than in whites, and is about four times more likely to cause blindness in blacks than whites.
Miggins, who is black, says she had heard of glaucoma. "But I didn't have a clue what it was, nor did I think I was at risk for it because it doesn't run in my family."
If you are in any of the high-risk groups for glaucoma--everyone over age 60, those with a family history of the disease, and blacks over age 40--you should get a complete eye exam at least every two years.
Though glaucoma is not curable, there are treatments that successfully lower pressure in the eye. The first line of treatment is drugs, and whether you're prescribed eye drops or pills, taking your drugs as prescribed is critical.
The development of several classes of medications to reduce pressure in the eye has allowed for more effective treatment over time, says Wiley Chambers, M.D., deputy director of the FDA's division of anti-inflammatory, analgesic and ophthalmic drug products. For now, glaucoma medications only tackle eye pressure, says Chambers. "We're looking for treatments that can also protect the optic nerve."
Miggins says the first medication she took caused bleeding gums and eye pain. Some side effects may lessen over time, but be sure to report them to your doctor because it could be that the drug or dose needs to be changed.
In March 2001, the FDA approved two new drugs to treat elevated eye pressure, Lumigan (bimatoprost ophthalmic solution), marketed by Allergan Inc. of Irvine, Calif., and Travatan (travoprost ophthalmic solution), marketed by Alcon Laboratories Inc. of Fort Worth, Texas. These medications provide alternatives for people who are intolerant or unresponsive to other drugs and who otherwise may need surgery. Potential side effects of these two drugs include gradual darkening of eye color and darkening of eyelid skin.
When glaucoma can't be controlled with medication, doctors may turn to laser surgery in which a focused beam of light creates openings in the part of the eye where fluid drains to make draining easier. The next line of treatment is a surgical procedure called trabeculectomy, in which a small opening is made in the front chamber of the eye to make a new pathway from which fluid can drain. Even with surgery, many patients who have glaucoma still need medication.
For those with very advanced disease, or when conventional medical and surgical treatments have failed to control the disease, glaucoma may be treated with a drainage device, a little plastic tube. These devices are surgically implanted to create a new drainage pathway. In July 2001, the FDA approved the AquaFlow Collagen Glaucoma Drainage Device from STAAR Surgical Company in Monrovia, Calif., to manage open-angle glaucoma. A small cylinder made of collagen is implanted in the eye to absorb excess fluid. The device is designed to maintain a space under the white part of the eye, and it slowly dissolves in the eye until it's completely absorbed within nine months, leaving behind a drainage route for the fluid.
The cause is unknown, but AMD occurs when light-sensing cells in the macula break down. The macula is the central part of the retina and is responsible for clear, sharp vision.
About 90 percent of people with AMD have what's known as the "dry" type, and the remaining 10 percent have the "wet" type. The wet type of AMD is more severe and causes the most vision loss. In the dry type, the light-sensitive vision cells deteriorate but there is no bleeding. In the wet type of AMD, new blood vessels grow and leak blood and fluid under the macula. For some people with the disease, vision is affected very slowly. But for others, the disease progresses rapidly over the course of weeks to months.
"Macular degeneration rarely leads to complete blindness, but often causes severe and irreversible loss of central vision," says Stuart L. Fine, M.D., chairman of the department of ophthalmology at the University of Pennsylvania. Side vision remains, but the center of vision, which is needed for daily tasks like reading and driving, is destroyed.
About 1.7 million Americans have some form of AMD, according to the National Eye Institute (NEI). It's the leading cause of vision loss among Americans ages 65 and over. The disease is painless, and common symptoms include blurry vision, distorted vision, such as seeing straight lines as crooked or wavy, or a dark, empty area appearing in the center of vision.
Dorothy Borne, 66, a retired food technician from Hahnville, La., was diagnosed with wet AMD and experienced blurriness in her left eye about three years ago. It presented abruptly because a large quantity of fluid leaked into the macula from abnormal blood vessels.
"When I got to work that morning, I noticed that everything looked blurry," she says. "I didn't know what was wrong."
Age and a family history of AMD are the biggest risk factors. People over age 60 are at the highest risk, and should get an eye exam at least every two years.
Fine says, "Other risk factors may include smoking, low lifetime intake of dark green leafy vegetables, high blood pressure, and cardiovascular disease. Some epidemiological studies have identified farsightedness and light eye color as risk factors."
According to NEI, women tend to be at greater risk for AMD than men, and whites are much more likely to lose vision from AMD than blacks.
Those at risk should get in the habit of checking their central vision in each eye separately by covering one eye while evaluating the other eye, Fine suggests. It is recommended that some patients keep an Amsler Grid on their refrigerator as a reminder to check their eyes at home. You look at the dot in the center of the grid to see if lines around it appear wavy or distorted, which could be a sign of AMD. Once you have AMD in one eye, there is a roughly 50 percent chance that it could occur in the other eye, so it's important to report any vision changes to your doctor and routinely test the other eye.
Studies have suggested that a diet rich in dark green, leafy vegetables such as spinach and collard or mustard greens lowers the risk of AMD. These foods are a source of nutrients such as vitamin A, vitamin C, and vitamin E. But experts say it's important to recognize that a balanced diet is generally important for eye health, the same way it is for the rest of the body.
Recent NEI research has shown that nutritional supplements--vitamin E, vitamin C, beta carotene, and zinc--may benefit some people who have advanced AMD. The American Academy of Ophthalmology recommends that if you have intermediate or advanced AMD in one eye only, you should talk with your physician about whether nutritional supplements may help you and how to take them safely. Not everybody needs supplements. For example, in large quantities, zinc can be toxic. Beta-carotene can increase the risk of lung cancer in smokers. High-dose nutrients can also interfere with medications and decrease the absorption of other nutrients into the body.
"For the dry form of AMD there is no specific treatment other than low vision rehabilitation, which shouldn't be underestimated," says Fine (see "Low-Vision Resources").
The biggest advance in AMD treatment so far was the approval in April 2000 of Visudyne (verteporfin for injection) for treatment of the classic type of wet AMD. About half of those with wet AMD have the classic type. Visudyne is manufactured by QLT Photo Therapeutics Inc., Seattle, and marketed by Novartis Ophthalmics, Duluth, Ga.
Visudyne can't restore vision that's been lost, but it can slow the loss of vision from AMD. It's injected into the patient's arm and it travels to the abnormal blood vessels in the eye. Then a laser is aimed at the patient's eye for a little over a minute to activate the drug. The drug works to stop or slow blood leakage. Common side effects include light sensitivity and reactions at the injection site.
Some cases of wet AMD can be treated with laser surgery. Again, lost vision usually can't be restored, but the laser aims a light beam onto new blood vessels to destroy them to preserve what central vision remains. Borne had laser surgery immediately and ended up having several more surgeries in the span of a few months, which left her with some scarring in the eye. "She needed the surgeries because some of the blood vessels around the macula continued to bleed," says Monica L. Monica, M.D., Borne's doctor and an ophthalmologist in New Orleans.
In the end, the laser surgeries stopped the bleeding. "If the hemorrhage isn't stopped, there could be even more extensive loss of vision than just central vision," Monica says.
Borne has lost central vision in her left eye, but still has side vision in that eye and can grossly see large objects like cars.
Borne, who can still see clearly out of her right eye, says, "I can read, just not for very long. After a while, words start jumbling together." She knows that if her right eye bothers her, day or night, she should call her doctor right away. "I just hope my right eye will stay OK," she says.
Cataracts are areas that distort light as it passes through the lens of the eye (opacities). The most common type of cataract is age-related. As we get older, protein in the lens of our eyes can clump together and cloud the lens, which is located behind the iris and the pupil. The lens is responsible for focusing light and producing sharp images.
Cataracts form slowly and typically cause no pain. In late 2000, David Guillot, 65, a retired aerospace engineer from Covington, La., noticed blurry vision. "I couldn't make out road signs even with my glasses on," he says. Shortly after, he was diagnosed with cataracts in both eyes. In addition to blurriness, common symptoms of cataracts are reduced night vision, problems with glare, frequent eyeglass prescription changes, impaired depth perception, and color distortion. Cataracts usually occur in both eyes.
Anyone can get cataracts, but it's for those over 60 that cataracts are most likely to interfere with vision. Cataracts can result from natural aging of the lens, but also can occur as a result of eye injury. An eye exam at least every two years is recommended for those over 60.
Some studies suggest that exposure to bright sunlight over several years may lead to cataracts, while other studies refute this, says Walter J. Stark, M.D., professor of ophthalmology at The Johns Hopkins University School of Medicine in Baltimore and director of the corneal and cataract services at the Wilmer Eye Institute. "The recommendation is that if one is outside a lot, say because of occupation, it may help to wear sunglasses that block ultraviolet rays," Stark says. "It won't hurt." Your sunglasses should offer 100 percent or nearly total UV protection. Wide-brimmed hats can also help block sunlight.
People with diabetes are at higher risk for cataracts, and smoking is a suspected risk factor. "It appears that smoking generally makes things worse when it comes to the eyes," Stark says. Taking corticosteroids for other medical conditions also can cause cataracts.
It had been believed that certain vitamins, such as vitamin C, might affect cataracts, but recent research has shown that nutritional supplements do not appear to prevent cataracts or keep them from getting worse.
For some people with cataracts, a stronger eyeglass prescription may be all that's needed. Keep up with regular eye appointments and talk with your doctor about how the cataracts affect your ability to work, read, and take part in other routine activities.
When cataracts interfere with daily activities, surgery may be recommended to remove the clouded lens and replace it with a new, artificial one. Monica says it's probably the most satisfying operation for an eye doctor and patient. Cataract surgery has an overall success rate of about 98 percent. According to NEI, it's the most frequently performed surgery in the United States, with over 1.5 million cataract surgeries performed each year.
Like any eye surgery, there are risks such as eye infection and swelling. "Cystoid macular edema is an uncommon complication of cataract surgery that causes swelling and blurry vision," says FDA's Berman.
The most common complication is formation of a secondary opacification (known as posterior capsular opacification) behind the new lens implant, Berman says. "This is treated with a laser that creates an opening through which clear vision is regained."
Just 10 years ago, cataract surgery required a hospital stay of several days. Now, the surgery can sometimes be done in less than 30 minutes on an outpatient basis. Guillot says his surgery took about 20 minutes and he went home that day. He had a cataract removed from one eye in June 2001, and had eye surgery on the second eye about three weeks later. His doctor broke up his cataracts with a high-frequency ultrasound. "I can see much better," Guillot says. "I can read the newspaper, watch TV, and I notice a big difference when I'm on the Internet. Sometimes I don't even need my glasses."
Advances in lens technology have improved cataract surgery over the last several years. "New lens materials, such as soft silicone, acrylic, and hydrogels, are more flexible and foldable," Berman says. "They permit surgery through smaller incisions and some appear to have lower rates of secondary opacification formation." And multifocal lens designs have been approved that provide both distance and near vision, so that reading glasses may not always be necessary. "Future advances might come," Berman says, "as a result of research on lens materials able to form a new lens within the eye itself."
When diabetes is uncontrolled, chronic high blood sugar levels can damage the blood vessels that feed the retina of the eye. In nonproliferative diabetic retinopathy (NPDR), an early stage of diabetic eye disease, the blood vessels may leak fluid. This may cause the retina to swell and vision to blur, a condition called diabetic macular edema. In what's known as advanced or proliferative diabetic retinopathy (PDR), abnormal new blood vessels grow on the surface of the retina. The abnormal blood vessels don't supply the retina with normal blood flow, and in addition may eventually pull on the retina and cause detachment.
Diabetic retinopathy is the leading cause of new cases of blindness, accounting for about 8,000 cases each year. It's the most common and serious threat to vision that people with diabetes face. Nearly half of all people with diabetes eventually develop some degree of diabetic retinopathy. It usually occurs in both eyes. There may be no early signs of the disease. More advanced cases may be signaled by floaters, blurred vision, eye pain, or gradual vision loss.
Experts say the rate of diabetic retinopathy is likely to get worse because the number of people with diabetes is increasing. About 16 million people have diabetes and many don't know it. In one recent National Institutes of Health study of Mexican-Americans over age 40, 23 percent of those who didn't know they had diabetes also had early to moderate diabetic retinopathy.
Uncontrolled diabetes is the prime risk factor for retinopathy. Diabetic retinopathy can usually be managed with a combination of tight blood sugar control, appropriate exercise and diet, and early detection. People who are diagnosed with diabetes before age 30 should begin having dilated exams every year beginning five years after diagnosis. All others with diabetes should have an eye exam every year. A recent study in the AAO's journal Ophthalmology showed that more than one-third of Americans with diabetes don't get a yearly dilated exam as recommended, putting them at risk for vision loss.
Some cases of diabetic retinopathy can be treated with laser surgery that aims a strong beam of light onto the retina to shrink or seal leaking or abnormal vessels. But it can't restore vision already lost, which is why early detection is important. In some advanced cases of PDR, a vitrectomy is recommended, in which the surgeon removes the vitreous portion of the eye and replaces it with a clear solution.
Josephine Grant, 54, a former cafeteria worker from Gaithersburg, Md., says she had diabetes for several years and then experienced major vision loss seven years ago because of diabetic retinopathy. She is blind in her right eye, and can see a little bit with the left eye. Unfortunately, Grant came to treatment with an advanced form of the disease, which made her prognosis poor, says T. S. Melki, M.D., the Maryland ophthalmologist who performed Grant's surgeries.
If laser surgery is done in time, he says, the disease can be stopped or slowed. Melki says hundreds of patients with diabetes come see him regularly, sometimes as frequently as every four to five months, so that the level of diabetic retinopathy can be followed closely. "If a patient has minimal disease then the follow-up is less frequent," Melki says. "There are some patients we refer to as 'The Golden Club,' who have had diabetes for over 20 years with no effect on the eye," he says. "So it can be done."
EyeCare America-National Eye Care Project, a program of the American
Academy of Ophthalmology to provide free or low-cost eye exams. Those who are
eligible are people who are 65 or older, U.S. citizens, not in a health maintenance
organization, not receiving care through the armed forces or Department of Veterans
Affairs, and who haven't seen an ophthalmologist in the last three years. 1-800-222-EYES
(1-800-222-3937)
Learn
more about this project.
Volunteers in Service in Our Nation (VISION) USA, a program to give free eye care to uninsured, low-income workers and their families, sponsored by the American Optometric Association. Eligibility requirements may vary by state. But generally, participants must have a job or live in a household where there is one working member, have no vision insurance, have income below an established level, and have not had an eye exam in the last two years. The deadline to enroll for free services in 2002 just passed. Learn more about the program.
In January 2003, you can call 1-800-766-4466. The toll-free line is only operational during January of each year.
Recommended Guidelines for Eye Exams |
|
|---|---|
| Before age 5: | Toddlers should be screened for common childhood problems such as crossed eye, lazy eye, nearsightedness and farsightedness. |
| Puberty to age 39: | Should be checked if you experience any eye problems or visual changes such as pain, floaters, flashes of light, blurry vision, or eye injury. |
| Ages 40 to 65: | Should be examined every two to four years. |
| Everyone over 65: | Should be examined every one to two years. |
| People at higher risk for eye diseases need to be examined
more often. For example, adults with diabetes should have yearly eye exams.
Other people at higher risk include blacks over age 40, people with a family
history of eye disease, or those with a history of eye injury. Source: American Academy of Ophthalmology |
|
There are many aids and devices that can help in low-vision situations. Among them are magnifying lenses you can mount on your glasses or on a headband, miniature telescopes to help see a television across the room, and talking wristwatches. Here are some organizations that can point you in the right direction for more on resources that help people with vision problems maintain their quality of life.
American Optometric Association
243 North Lindbergh Blvd.
St. Louis, MO. 63141
www.aoa.org
Lighthouse International
111 E. 59th St.
New York, NY 10022
1-800-829-0500
TTY: 212-821-9713
www.lighthouse.org
National Association for Visually Handicapped
22 W. 21st St., 6th Floor
New York, NY 10010
212-889-3141
and
3201 Balboa St.
San Franciso, CA 94121
415-221-3201
www.navh.org
National Eye Institute, National Institutes of Health
2020 Vision Place
Bethesda, MD 20892
301-496-5248
www.nei.nih.gov
National Federation of the Blind
1800 Johnson St.
Baltimore, MD 21230
410-659-9314
www.nfb.org
Prevent Blindness America
500 E. Remington Rd.
Schaumburg, IL 60173
1-800-331-2020
www.preventblindness.org
The retina is the light-sensitive layer of tissue that lines the inside of the back of the eye and sends visual messages to the brain. If the retina detaches from its normal position, permanent vision loss can result.
While anyone can experience retinal detachment, head or eye injuries and certain eye conditions increase the risk. These include myopia, commonly known as nearsightedness, and posterior vitreous detachment, which occurs when the vitreous (the jelly-like fluid in the eye) breaks away from the back of the eye. The most common symptom of a posterior vitreous detachment is a condition called floaters, specks or strands that appear to float in the field of vision. Sometimes when the vitreous breaks away it can tear the retina, which can lead to retinal detachment.
Symptoms of retinal detachment include seeing floaters, flashes of light, or the appearance of a curtain over the field of vision. It's important to see an eye-care professional immediately if you experience these symptoms because early treatment is critical for restoring vision.
Small holes and tears in the retina may be treated in a doctor's office with laser surgery, which uses tiny burns to seal the retina back into place. Another treatment, cryopexy, freezes the area around the hole in the retina. Retinal detachments may require surgical treatment to reattach the retina and a hospital stay.
Source: National Eye Institute, National Institutes of Health
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