What are the symptoms of glaucoma?
What are the treatments for glaucoma?
Where can I get more information about glaucoma?
What is glaucoma?
Glaucoma is a potentially blinding eye disease in which there is gradual damage to the nerve fibers of the optic nerve. This nerve registers what we see, because it connects the ganglion cells of the retina to the vision center in the brain. Usually, but not always, the damage of glaucoma results from elevated pressure inside the eyeball. Defects in the drainage system for the aqueous fluid (which determines the pressure within the eye) can raise the intraocular pressure (IOP) above normal levels.
Primary open-angle glaucoma (POAG) is the most common form in the U.S. It usually affects people over age 40, and is, therefore, considered an age-related disease. Women live, on average, several years longer than do men in industrialized countries like the U.S. For this reason, many more women than men live long enough to develop glaucoma. Blacks are much more susceptible than whites; scientists don’t know why. Over two million Americans have the disease, and half of them don’t know they have it. An estimated 80,000 people in the US are legally blind, in both eyes, from glaucoma. It is the principal cause of blindness among blacks, and the second-leading cause (after age-related macular degeneration) of blindness overall in the American population. Much of this suffering could have been prevented by early diagnosis and treatment of the disease. There is widespread ignorance about glaucoma. Many people think that it is painful or that it is caused by high blood pressure; both of these statements are false, and can lead to a false sense of security.
Who is at risk for glaucoma?
People with a family history of glaucoma, blacks, diabetics, and people who are either very nearsighted (high myopes) or who are taking steroids on a long-term basis, are at much higher risk of developing glaucoma. The overall prevalence of POAG in the U.S. is about one percent, but in black populations it has been reported to range from two to nine percent.
The older you are, the more chance you have of developing glaucoma. This is the main reason why it is recommended that people over age 60, even apparently healthy ones, see an eye doctor at least every two years.
What are the symptoms of glaucoma?
Glaucoma is silent; this makes it extremely dangerous. There is no pain in POAG and no changes in vision at first, even though the optic nerve is slowly being damaged. Glaucoma can be a blinding disease if left untreated. This is why there is a great need to diagnose this disease early, before there is any loss of vision. Glaucoma is the best example of a serious eye disease for which early detection really helps, because there are effective treatments that will prevent or slow vision loss. In later stages of the disease, if it is not treated, there is a gradual, bilateral loss of peripheral vision; this means that you fail to see objects that aren’t right in front of you. Gradually your field of useful vision will get smaller and smaller.
Can glaucoma be prevented?
Glaucoma cannot, at present, be prevented. However, if it is detected early, before there is significant vision loss, it can be controlled. The aim is to keep as many as possible of the 100,000 retinal ganglion cells in each eye alive and healthy; these are nerve cells and cannot replenish themselves. Therefore, vigilance is the key to preventing blindness. Everyone should have his or her intraocular pressure checked by an ophthalmologist or optometrist at age 40, and regularly thereafter. The instrument the doctor uses to measure pressure is called a tonometer. However, this test is not enough because, in many cases of glaucoma, the pressure within the eyeball is not elevated. Therefore, even if you have no symptoms, you should get a thorough eye exam from an eye-care doctor, through dilated pupils, at least every two years starting at age 60 if you are white, and age 40 if you are black. Your eye-care professional will look for optic-nerve “cupping” and changes in the appearance of the retina and the retinal blood vessels. If anything looks abnormal, the doctor will measure the extent of your visual field by a painless method called perimetry.
If you are black, or if glaucoma runs in your family, you are at much higher risk of developing glaucoma. Therefore, if you are in one (or both) of these categories, you should get complete eye examinations more frequently, starting at a younger age, in order to get treatment before permanent damage is done.
What are the treatments for glaucoma?
There is no cure for glaucoma, and any vision lost to the disease
cannot be brought back. However, prescription eye drops can often control
the disease. The drops act by decreasing aqueous humor formation (this
formation brings fluid into the eye), thereby lowering eye pressure.
These eye drops, and medicines in pill form, are usually the first method
of treatment used. The drops and pills are effective in delaying (and
maybe even preventing) optic-nerve damage. Laser surgery may be used,
to increase drainage of aqueous fluid out of the eye, especially if
medications do not help enough. If these methods do not control the
progress of glaucoma, conventional surgery may be necessary, to make
a new opening for fluid to leave the eye.
If an older person has already been diagnosed with glaucoma (even at an early stage), Medicare will pay for future visits.
Much current research is directed at learning why retinal ganglion cells die in glaucoma. Some of this research is parallel to scientists asking why brain cells die during a stroke. Hopefully, in the future, new, molecular-based treatments can be developed specifically to prevent damage to the optic nerve.
Where can I get more information about glaucoma?
The National Eye Institute (NEI), a branch of the National Institutes of Health, has lots of reliable, easily understood information available on its website. For example, you can see what the world might look like to a person with glaucoma, and learn how the aqueous fluid, responsible for maintaining eye pressure, is formed and how it drains out of the eye. You can find out if free or low-cost eye screenings by eye care professionals are available to qualifying individuals in your area.
All of the NEI information is available, free, by writing to: National Eye Health Education Program, 2020 Vision Place, Bethesda, MD 20892-3655.
Both Schepens Eye Research Institute and Prevent Blindness America have fact sheets available on glaucoma and other eye problems. The Glaucoma Research Foundation also has lots of information.
