What is a cataract?
A cataract is a clouding of the eye's lens that causes loss of vision. This document is about age-related cataract, the most common type.
What causes it?
The lens lies behind the iris and the pupil. It works much like a camera lens. It focuses light onto the retina at the back of the eye, where an image is recorded. The lens also adjusts the eye's focus, letting us see things clearly both up close and far away.
The lens is made of mostly water and protein. The protein is arranged in a precise way that keeps the lens clear and lets light pass through it.
But as we age, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract. Over time, the cataract may grow larger and cloud more of the lens, making it harder to see.
Researchers suspect that there are several causes of cataract, such as smoking and diabetes. Or, it may be that the protein in the lens just changes from the wear and tear it takes over the years.
When are you most likely to have a cataract?
The term "age-related" is a little misleading. You don't have to be a senior citizen to get this type of cataract. In fact, people can have an age-related cataract in their 40s and 50s. But during middle age, most cataracts are small and do not affect vision. It is after age 60 that most cataracts steal vision.
What are its symptoms?
A cataract starts out small. It has little effect on vision at first. You may notice that your vision is blurred a little, like looking through a cloudy piece of glass.
A cataract may make light from the sun or a lamp seem too bright, causing a glare. Or, you may notice when you drive at night that the oncoming headlights cause more glare than before. Also, colors may not appear as bright to you as they once did.
As the cataract gets bigger and clouds more of the lens (some doctors use the term, "ripens"), you will find it harder to read and do other normal tasks. The word "cataract" means waterfall. For people with a ripe cataract, it is like trying to see through a waterfall.
How is a cataract detected?
Although you might think you have a cataract, the only way to know for sure is by having an eye examination. Should your eye care professional find one, he or she can monitor it and advise you about any future treatment.
How is a cataract treated?
It is treated with surgery. Your eye care professional will remove your clouded lens and, in most cases, replace it with a clear, plastic lens. Cataract surgery is very successful in restoring vision. In fact, it is one of the most common surgeries performed in the United States, with over 1.5 million cataract surgeries done each year.
When should a cataract be treated?
If your eye care professional finds a cataract, you may not need cataract surgery for several years. In fact, you might never need cataract surgery. By having your vision tested regularly, you and your eye care professional can discuss if and when you might need treatment.
What can you do to protect your vision?
If you are over age 60, you should have an eye examination at least once every two years. This exam should include dilating your pupils. This means drops are put into your eyes to enlarge your pupils. Although a cataract can be detected without dilated pupils, your eye care professional can see the back of your eye better using this exam. Getting a good view of the retina and optic nerve is important in detecting eye diseases such as glaucoma and macular degeneration.
To learn more about cataract write: National Eye Health Education Program, 2020 Vision Place, Bethesda, MD 20892-3655.
Source: National Eye Institute, National Institutes of Health.
What is glaucoma?
Glaucoma is a group of diseases that can damage the eye's optic nerve and result in vision loss and blindness. However, with early treatment, you can often protect your eyes against serious vision loss.
What is the optic nerve?
The optic nerve is a bundle of more than 1 million nerve fibers. It connects the retina to the brain. The retina is the light-sensitive tissue at the back of the eye. A healthy optic nerve is necessary for good vision.
How does open-angle glaucoma damage the optic nerve?
In the front of the eye is a space called the anterior chamber. A clear fluid flows continuously in and out of the chamber and nourishes nearby tissues. The fluid leaves the chamber at the open angle where the cornea and iris meet. When the fluid reaches the angle, it flows through a spongy meshwork, like a drain, and leaves the eye.
Sometimes, when the fluid reaches the angle, it passes too slowly through the meshwork drain. As the fluid builds up, the pressure inside the eye rises to a level that may damage the optic nerve. When the optic nerve is damaged from increased pressure, open-angle glaucoma--and vision loss--may result. That's why controlling pressure inside the eye is important.
Does increased eye pressure mean that I have glaucoma?
Not necessarily. Increased eye pressure means you are at risk for glaucoma, but does not mean you have the disease. A person has glaucoma only if the optic nerve is damaged. If you have increased eye pressure but no damage to the optic nerve, you do not have glaucoma. However, you are at risk. Follow the advice of your eye care professional.
Will I develop glaucoma if I have increased eye pressure?
Not necessarily. Not every person with increased eye pressure will develop glaucoma. Some people can tolerate higher eye pressure better than others. Also, a certain level of eye pressure may be high for one person but normal for another.
Whether you develop glaucoma depends on the level of pressure your optic nerve can tolerate without being damaged. This level is different for each person. That's why a comprehensive dilated eye exam is very important. It can help your eye care professional determine what level of eye pressure is normal for you.
Can I develop glaucoma without an increase in my eye pressure?
Yes. Glaucoma can develop without increased eye pressure. This form of glaucoma is called low-tension or normal-tension glaucoma. It is not as common as open-angle glaucoma.
Who is at risk for open-angle glaucoma?
Anyone can develop glaucoma. Some people are at higher risk than others. They include:
*African Americans and Latinos over age 40
*Everyone over age 60, especially Mexican Americans
*People with a family history of glaucoma
A comprehensive dilated eye exam can reveal more risk factors, such as high eye pressure, thinness of the cornea, and abnormal optic nerve anatomy. In some people with certain combinations of these high-risk factors, medicines in the form of eyedrops reduce the risk of developing glaucoma by about half.
What are the symptoms of glaucoma?
At first, open-angle glaucoma has no symptoms. It causes no pain. Vision stays normal.
As glaucoma remains untreated, people may miss objects to the side and out of the corner of their eye. Without treatment, people with glaucoma will slowly lose their peripheral (side) vision. They seem to be looking through a tunnel. Over time, straight-ahead vision may decrease until no vision remains.
Glaucoma can develop in one or both eyes.
Can glaucoma be cured?
No. There is no cure for glaucoma. Vision lost from the disease cannot be restored.
Can glaucoma be treated?
Yes. Immediate treatment for early stage, open-angle glaucoma can delay progression of the disease. That's why early diagnosis is very important.
Glaucoma treatments include medicines, laser trabeculoplasty, conventional surgery, or a combination of any of these. While these treatments may save remaining vision, they do not improve sight already lost from glaucoma.
Medicines. Medicines, in the form of eyedrops or pills, are the most common early treatment for glaucoma. Some medicines cause the eye to make less fluid. Others lower pressure by helping fluid drain from the eye.
Before you begin glaucoma treatment, tell your eye care professional about other medicines you may be taking. Sometimes the drops can interfere with the way other medicines work.
Glaucoma medicines may be taken several times a day. Most people have no problems. However, some medicines can cause headaches or other side effects. For example, drops may cause stinging, burning, and redness in the eyes.
Many drugs are available to treat glaucoma. If you have problems with one medicine, tell your eye care professional. Treatment with a different dose or a new drug may be possible.
Because glaucoma often has no symptoms, people may be tempted to stop taking, or may forget to take, their medicine. You need to use the drops or pills as long as they help control your eye pressure. Regular use is very important. Make sure your eye care professional shows you how to put the drops into your eye.
Laser trabeculoplasty. Laser trabeculoplasty helps fluid drain out of the eye. Your doctor may suggest this step at any time. In many cases, you need to keep taking glaucoma drugs after this procedure.
Laser trabeculoplasty is performed in your doctor's office or eye clinic. Before the surgery, numbing drops will be applied to your eye. As you sit facing the laser machine, your doctor will hold a special lens to your eye. A high-intensity beam of light is aimed at the lens and reflected onto the meshwork inside your eye. You may see flashes of bright green or red light. The laser makes several evenly spaced burns that stretch the drainage holes in the meshwork. This allows the fluid to drain better.
Like any surgery, laser surgery can cause side effects, such as inflammation. Your doctor may give you some drops to take home for any soreness or inflammation inside the eye. You need to make several followup visits to have your eye pressure monitored.
If you have glaucoma in both eyes, only one eye will be treated at a time. Laser treatments for each eye will be scheduled several days to several weeks apart.
Studies show that laser surgery is very good at reducing the pressure in some patients. However, its effects can wear off over time. Your doctor may suggest further treatment.
Conventional surgery. Conventional surgery makes a new opening for the fluid to leave the eye. Your doctor may suggest this treatment at any time. Conventional surgery often is done after medicines and laser surgery have failed to control pressure.
Conventional surgery is performed in an eye clinic or hospital. Before the surgery, you will be given medicine to help you relax. Your doctor will make small injections around the eye to numb it. A small piece of tissue is removed to create a new channel for the fluid to drain from the eye.
For several weeks after the surgery, you must put drops in the eye to fight infection and inflammation. These drops will be different from those you may have been using before surgery.
As with laser surgery, conventional surgery is performed on one eye at a time. Usually the operations are four to six weeks apart.
Conventional surgery is about 60 to 80 percent effective at lowering eye pressure. If the new drainage opening narrows, a second operation may be needed. Conventional surgery works best if you have not had previous eye surgery, such as a cataract operation.
In some instances, your vision may not be as good as it was before conventional surgery. Conventional surgery can cause side effects, including cataract, problems with the cornea, and inflammation or infection inside the eye. The buildup of fluid in the back of the eye may cause some patients to see shadows in their vision. If you have any of these problems, tell your doctor so a treatment plan can be developed.
What are some other forms of glaucoma?
Open-angle glaucoma is the most common form. Some people have other types of the disease.
In low-tension or normal-tension glaucoma, optic nerve damage and narrowed side vision occur in people with normal eye pressure. Lowering eye pressure at least 30 percent through medicines slows the disease in some people. Glaucoma may worsen in others despite low pressures.
A comprehensive medical history is important in identifying other potential risk factors, such as low blood pressure, that contribute to low-tension glaucoma. If no risk factors are identified, the treatment options for low-tension glaucoma are the same as for open-angle glaucoma.
In angle-closure glaucoma, the fluid at the front of the eye cannot reach the angle and leave the eye. The angle gets blocked by part of the iris. People with this type of glaucoma have a sudden increase in eye pressure. Symptoms include severe pain and nausea, as well as redness of the eye and blurred vision. If you have these symptoms, you need to seek treatment immediately. This is a medical emergency. If your doctor is unavailable, go to the nearest hospital or clinic. Without treatment to improve the flow of fluid, the eye can become blind in as few as one or two days. Usually, prompt laser surgery and medicines can clear the blockage and protect sight.
In congenital glaucoma, children are born with a defect in the angle of the eye that slows the normal drainage of fluid. These children usually have obvious symptoms, such as cloudy eyes, sensitivity to light, and excessive tearing. Conventional surgery typically is the suggested treatment, because medicines may have unknown effects in infants and be difficult to administer. Surgery is safe and effective. If surgery is done promptly, these children usually have an excellent chance of having good vision.
Secondary glaucomas can develop as complications of other medical conditions. These types of glaucomas are sometimes associated with eye surgery or advanced cataracts, eye injuries, certain eye tumors, or uveitis (eye inflammation). Pigmentary glaucoma occurs when pigment from the iris flakes off and blocks the meshwork, slowing fluid drainage. A severe form, called neovascular glaucoma, is linked to diabetes. Corticosteroid drugs used to treat eye inflammations and other diseases can trigger glaucoma in some people. Treatment includes medicines, laser surgery, or conventional surgery.
What can I do if I already have lost some vision from glaucoma?
If you have lost some sight from glaucoma, ask your eye care professional about low vision services and devices that may help you make the most of your remaining vision. Ask for a referral to a specialist in low vision. Many community organizations and agencies offer information about low vision counseling, training, and other special services for people with visual impairments. A nearby school of medicine or optometry may provide low vision services.
What research is being done?
Through studies in the laboratory and with patients, the National Eye Institute is seeking better ways to detect, treat, and prevent vision loss in people with glaucoma. For example, researchers have discovered genes that could help explain how glaucoma damages the eye.
The NEI also is supporting studies to learn more about who is likely to get glaucoma, when to treat people with increased pressure, and which treatment to use first.
What can I do to protect my vision?
If you are being treated for glaucoma, be sure to take your glaucoma medicine every day. See your eye care professional regularly.
You also can help protect the vision of family members and friends who may be at high risk for glaucoma--African Americans over age 40; everyone over age 60, especially Latinos; and people with a family history of the disease. Encourage them to have a comprehensive dilated eye exam at least once every two years. Remember: Lowering eye pressure in glaucoma's early stages slows progression of the disease and helps save vision.
Medicare covers an annual comprehensive dilated eye exam for some people at high risk for glaucoma. These people include those with diabetes, those with a family history of glaucoma, and African Americans age 50 and older.
What should I ask my eye care professional?
You can protect yourself against vision loss by working in partnership with your eye care professional. Ask questions and get the information you need to take care of yourself and your family.
What are some questions to ask?
About my eye disease or disorder:
* What is my diagnosis?
* What caused my condition?
* Can my condition be treated?
* How will this condition affect my vision now and in the future?
* Should I watch for any particular symptoms and notify you if they occur?
* Should I make any lifestyle changes?
About my treatment:
* What is the treatment for my condition?
* When will the treatment start and how long will it last?
* What are the benefits of this treatment and how successful is it?
* What are the risks and side effects associated with this treatment?
* Are there foods, drugs, or activities I should avoid while I'm on this treatment?
* If my treatment includes taking medicine, what should I do if I miss a dose?
* Are other treatments available?
About my tests:
* What kinds of tests will I have?
* What can I expect to find out from these tests?
* When will I know the results?
* Do I have to do anything special to prepare for any of the tests?
* Do these tests have any side effects or risks?
* Will I need more tests later?
Other suggestions:
* Ask questions until you understand
* Take notes or bring a tape recorder to help you remember the discussion
* Ask for written instructions and printed material
Today, patients take an active role in their health care. Be an active patient about your eye care.
Source: National Eye Institute, National Institutes of Health.
What is age-related macular degeneration (AMD)?
AMD is a common eye disease associated with aging that gradually destroys sharp, central vision. Central vision is needed for seeing objects clearly and for common daily tasks such as reading and driving. In some people, AMD advances so slowly that it will have little effect on their vision as they age. But in others, the disease progresses faster and may lead to a loss of vision in one or both eyes.
How does AMD damage vision?
The retina is a paper-thin tissue that lines the back of the eye and sends visual signals to the brain. In the middle of the retina is a tiny area called the macula. The macula is made up of millions of light-sensing cells that help to produce central vision.
AMD occurs in two forms:
* Dry AMD--Ninety percent of all people with AMD have this type. Scientists are still not sure what causes dry AMD. Studies suggest that an area of the retina becomes diseased, leading to the slow breakdown of the light-sensing cells in the macula and a gradual loss of central vision.
* Wet AMD--Although only 10 percent of all people with AMD have this type, it accounts for 90 percent of all blindness from the disease. As dry AMD worsens, new blood vessels may begin to grow and cause "wet" AMD. Because these new blood vessels tend to be very fragile, they will often leak blood and fluid under the macula. This causes rapid damage to the macula that can lead to the loss of central vision in a short period of time.
Who is most likely to get AMD?
The greatest risk factor is age. Although AMD may occur during middle age, studies show that people over age 60 are clearly at greater risk than other age groups. For instance, a large study found that people in middle-age have about a 2 percent risk of getting AMD, but this risk increased to nearly 30 percent in those over age 75.
Other AMD risk factors include:
Gender--Women tend to be at greater risk for AMD than men.
Race--Whites are much more likely to lose vision from AMD than Blacks.
Smoking--Smoking may increase the risk of AMD.
Family History--Those with immediate family members who have AMD are at a higher risk of developing the disease.
What are the symptoms?
Both dry and wet AMD cause no pain. The most common early sign of dry AMD is blurred vision. As fewer cells in the macula are able to function, people will see details less clearly in front of them, such as faces or words in a book. Often this blurred vision will go away in brighter light. If the loss of these light-sensing cells becomes great, people may see a small, but growing,blind spot in the middle of their field of vision.
The classic early symptom of wet AMD is that straight lines appear crooked. This results when fluid from the leaking blood vessels gathers and lifts the macula, distorting vision. A small blind spot may also appear in wet AMD, resulting in loss of one's central vision.
How is it detected?
Your eye care professional may suspect AMD if you are over age 60 and have had recent changes in your central vision. To look for signs of the disease, he or she will use eye drops to dilate, or enlarge, your pupils. Dilating the pupils allows your eye care professional to view the back of the eye better.
Normal Macula vs. Macula with AMD
You may also be asked to view an Amsler grid, a pattern that looks like a checkerboard. Early changes in your central vision will cause the grid to appear distorted, a sign of AMD.
How can it be treated?
No treatment now exists for dry AMD. It has been suggested that taking certain extra vitamins and minerals may slow the progress of the disease. But this treatment needs much more research before scientists can know for sure if it's helpful.
Eye care professionals can treat some cases of wet AMD with laser surgery. This treatment involves aiming a strong light beam onto the new blood vessels to destroy them. Laser surgery is done in a doctor's office or in an eye clinic and lasts a short period of time. Although a person may go home the same day, he or she will need to return for follow-up exams.
What research is being done?
The National Eye Institute is funding a number of research studies to learn what causes AMD and how it can be better treated. For instance, in the Age-Related Eye Diseases Study (AREDS), researchers are assessing the aging process in the eyes of thousands of older people to discover the earliest signs of AMD. The same study is also evaluating the effects of certain vitamins and minerals in preventing or slowing the progress of AMD.
At the same time, other scientists are trying to learn more about how the cells in the retina work. This knowledge will allow them some day to pinpoint the cause of the disease and design methods to prevent it.
What can you do to protect your vision?
Although there is no effective treatment for dry AMD at this time, it is crucial that those who progress to wet AMD and need laser surgery have it before the disease destroys central vision. For this reason, if you have dry AMD or are age 60 or older, you should have your eyes examined through dilated pupils at least once a year. You may also want to get an Amsler grid from your eye care professional to check your vision at home.
To learn more about AMD, write: National Eye Health Education Program, 2020 Vision Place, Bethesda, MD 20892-3655.
Source: National Eye Institute, National Institutes of Health.
