What is glaucoma?
Glaucoma is a leading cause of blindness in the United States, especially for older people. But loss of sight from glaucoma is preventable if you get treatment early enough.
Glaucoma is a disease of the optic nerve. The optic nerve carries the images we see to the brain. Many people know that glaucoma has something to do with pressure inside the eye. The higher the pressure inside the eye, the greater the chance of damage to the optic nerve.
The optic nerve is like an electric cable containing a huge number of wires. Glaucoma can damage nerve fibers, causing blind spots to develop.
Often people don’t notice these blind areas until much optic nerve damage has already occurred. If the entire nerve is destroyed, blindness results. Early detection and treatment by your ophthalmologist are the keys to preventing optic nerve damage and blindness from glaucoma.
What causes glaucoma?
Clear liquid, called the aqueous humor, flows in and out of the eye. The liquid is not part of the tears on the outer surface of the eye. You can think of the flow of aqueous fluid as a sink with the faucet turned on all the time. If the “drainpipe” gets clogged, water collects in the sink and pressure builds up. If the drainage area of the eye (called the drainage angle) is blocked, the fluid pressure within the inner eye may increase, which can damage the optic nerve.
What are the different types of glaucoma?
Chronic open-angle glaucoma: This is the most common glaucoma. It occurs as a result of aging. The “drainpipe,” or drainage angle of the eye, becomes less efficient with time, and pressure within the eye gradually increases. If this increased pressure results in optic nerve damage, it is known as chronic open-angle glaucoma. Over 90% of adult glaucoma patients have this type of glaucoma. Chronic open-angle glaucoma can damage vision so gradually and painlessly that you are not aware of trouble until the optic nerve is already badly damaged.
Angle-closure glaucoma: Sometimes the drainage angle of the eye may become completely blocked. It is as though a sheet of paper floating near a drain suddenly slips over the opening and blocks the flow out of the sink. In the eye, the iris may act like the sheet of paper closing off the drainage angle. When eye pressure builds up rapidly, it is called acute angle-closure glaucoma. The symptoms include:
Severe eye pain
Rainbow haloes around lights
Nausea and vomiting
If you have any of these symptoms, call your ophthalmologist immediately. Unless an ophthalmologist treats acute angle-closure glaucoma quickly, blindness can result. A more gradual and painless closing of the angle is called chronic angle-closure glaucoma. It occurs more frequently in people of African and Asian ancestry.
How is glaucoma detected?
Regular eye examinations by your eye doctor are the best way to detect glaucoma. During a complete and painless examination, your eye doctor will:
Measure your intraocular pressure (tonometry)
Inspect the drainage angle of your eye (gonioscopy)
Evaluate any optic nerve damage (ophthalmoscopy)
Test the vision of each eye (visual field)
Some of these tests may not be necessary for every person. You may need to repeat these tests on a regular basis, to determine if glaucoma damage is increasing over time.
Who is at risk for glaucoma?
High pressure alone does not mean that you have glaucoma. Your eye doctor puts together many kinds of information to determine your risk for developing the disease. The most important risk factors include:
African or Asian ancestry
A family history of glaucoma
Past injuries to the eyes
A history of severe anemia or shock
Your eye doctor will weigh all of these factors before deciding whether you need treatment for glaucoma or whether you should be monitored closely as a glaucoma suspect. This means your risk of developing glaucoma is higher than normal, and you need to have regular examinations to detect early signs of damage to the optic nerve.
How is glaucoma treated?
As a rule, damage caused by glaucoma cannot be reversed. Eye drops, pills and laser and surgical operations are used to prevent or slow further damage from occurring. With any type of glaucoma, periodic examinations are very important to prevent vision loss. Because glaucoma can worsen without your being aware of it, your treatment may need to be changed over time.
Glaucoma is usually controlled with eye drops taken several times a day, sometimes in combination with pills. These medications decrease eye pressure, either by slowing the production of aqueous fluid within the eye or by improving the flow leaving the drainage angle. For these medications to work, you must take them regularly and continuously. It is also important to tell all of your doctors about the eye medications you are using.
Glaucoma medications can have side effects. You should notify your eye doctor immediately if you think you may be experiencing side effects.
Laser surgery treatments may be effective for different types of glaucoma. The laser is usually used in one of two ways. In open-angle glaucoma, the drain itself is treated. The laser is used to enlarge the drain (trabeculoplasty) to help control eye pressure. In angle-closure glaucoma, the laser creates a hole in the iris (iridotomy) to improve the flow of aqueous fluid to the drain.
When surgery is needed to control glaucoma, your ophthalmologist uses miniature instruments to create a new drainage channel for the aqueous fluid to leave the eye. The new channel helps to lower the pressure. Though serious complications of modern glaucoma surgery are rare, they can occur, as with any surgery. Surgery is recommended only if your ophthalmologist feels that it is safer to operate than to allow optic nerve damage to continue.
What is my part?
Treatment for glaucoma requires a “team” made up of both you and your doctor. Your eye doctor can prescribe treatment for glaucoma, but only you can make sure that you take your eye drops or pills. Never stop taking or change your medications without first consulting your eye doctor.
Frequent eye examinations and tests are critical to monitor your eyes for any changes. Remember, it is your vision, and you must do your part to maintain it. Loss of vision can be prevented! Regular medical eye exams may help prevent unnecessary vision loss.