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, early treatment of symptoms means you can often protect your eyes against serious vision loss.
Comparison of a person with normal vision VS. a person's vision with Glaucoma.
The optic nerve is a bundle of more than one million nerve fibres. It connects the retina to the brain. (See diagram below.) The retina is the light-sensitive tissue at the back of the eye. A healthy optic nerve is necessary for good vision.
In the front of the eye there 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.
Not necessarily. Increased eye pressure means you are at risk from 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.
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 an eye exam is very important. It can help your eye care professional determine what level of eye pressure is normal for you.
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.
There are several factors which increase the risk.
Age: glaucoma becomes much more common with increasing age. It is uncommon below the age of 40 but affects one per cent of people over this age and five per cent over 65.
Ethnicity: Afro-Caribbeans are more at risk of chronic glaucoma and it may come on somewhat earlier and be more severe. So make sure that you have regular tests.
Family: If you have a close relative who has chronic glaucoma then you should have an eye test at regular intervals. You should advise other members of your family to do the same. This is especially important if you are aged over 40 when tests should be done every year.
Short sight: People with a high degree of short sight are more prone to chronic glaucoma.
Diabetes is believed to increase the risk of developing this condition. Please note: People over the age of 40 years with an immediate family member diagnosed with glaucoma – parents, children or siblings – are entitled to a free sight test every year under the NHS.
A comprehensive 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 eye drops reduce the risk of developing glaucoma by about half.
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.
Glaucoma is detected through a comprehensive eye exam.
No. There is no cure for glaucoma. Vision lost from the disease cannot be restored.
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, in the form of eye drops 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 helps fluid drain out of the eye. Your ophthalmologist 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 hospital. Before the surgery, numbing drops will be applied to your eye. As you sit facing the laser machine, your ophthalmologist 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 ophthalmologist may give you some drops to take home for any soreness or inflammation inside the eye. You need to make several follow-up 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 ophthalmologist may suggest further treatment.
Conventional surgery makes a new opening for the fluid to leave the eye. Your ophthalmologist 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 ophthalmologist 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% 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 ophthalmologist so a treatment plan can be developed.
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% 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 GP 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 glaucoma are sometimes associated with eye surgery or advanced cataracts, eye injuries, certain eye tumours, 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.
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. Many community organisations 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.
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:
Age: glaucoma affects one per cent of people over 40 and five per cent over 65.
Please visit the Glaucoma optomap retinal screening images.
Text, images and photographs taken from National Eye Institute (NEI), National Institutes of Health (NIH). For more information on glaucoma visit www.nei.nih.gov or www.glaucoma-association.com.
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