Glaucoma is a leading cause of blindness in the United States, especially for older people. But loss of sight from glaucoma is often 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. High pressure inside the eye is a risk factor for developing glaucoma, although many people with "normal range" pressures develop the disease.
The optic nerve is made up of a huge number of nerve fibers, like an electric cable containing a huge number of wires. Glaucoma can damage nerve fibers, causing blind spots to develop.
Usually 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.
Clear liquid, called the aqueous humor, circulates inside the eye. A small amount of this fluid is produced constantly, and an equal amount flows out of the eye through a microscopic drainage system (this liquid is not part of the tears on the outer surface of the eye).
(Under picture) The clear aqueous humor is constantly produced within the eye (left). If the drainage angle of the eye is blocked, excess fluid cannot flow out of the eye (right).
You can think of the flow of the aqueous fluid as a sink with the faucet turned on all the time. If the "drainpipe" gets clogged, water collects in the sink and the sink may overflow. However, the eye is a closed structure, and, the excess fluid cannot overflow. If the drainage angle in the eye is blocked, the fluid pressure within the eye may increase, which can damage the optic nerve.
Chronic open-angle glaucoma: This is the most common form of glaucoma in the United States. Over 90% of adult glaucoma patients have this type of glaucoma. Chronic open-angle glaucoma damages vision so gradually and painlessly that you are not aware of trouble until the optic nerve is already badly damaged. The drainage angle of the eye becomes less efficient with time, and pressure within the eye gradually increases.
Angle-closure glaucoma: Sometimes the drainage angle of the eye may become physically blocked by a narrow angle. In the eye, the iris (the part that makes eyes blue or brown) and the cornea form the chamber angle, which houses the drainage tissue.
If the angle is narrow, it can close off the drainage tissue slowly over time, or suddenly.
Symptoms may include:
In some patients glaucoma has features of both the open-angle type and the angle-closure type, called mixed mechanism glaucoma. It occurs more frequently in people of African and Asian descent.
Regular eye examinations by your ophthalmologist are the best way to detect glaucoma. An ophthalmologist is a medical doctor. Your ophthalmologist can detect and treat glaucoma.
During a complete and painless examination, your ophthalmologist will:
High pressure alone does not mean that you have glaucoma, and you can develop glaucoma even with normal pressures. Your ophthalmologist puts together many kinds of information to determine your risk for developing the disease.
The most important risk factors include:
This means your risk of developing glaucoma is higher than normal, and you need to have regular examinations to detect the early signs of damage to the optic nerve.
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 may be controlled with eye drops, sometimes in combination with pills. These medications decrease eye pressure, either by slowing the production of aqueous fluids within the eye or by improving the flow through 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 ophthalmologist immediately if you think you may be experiencing side effects.
Some eye drops may cause:
Pills sometimes cause:
In open-angle glaucoma, the drain itself is treated. The laser is used to modify the drain (trabeculosplasty) 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 operative 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 if your ophthalmologist feels that it is safer to operate than to allow optic nerve damage to continue.
Treatment for glaucoma requires teamwork between you and your doctor. Your ophthalmologist can prescribe treatment for glaucoma, but only you can make sure you take your eye drops or pills.
Never stop taking or change your medications without first consulting your ophthalmologist. 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.
Regular medical eye exams may help prevent unnecessary vision loss. Recommended intervals for eye exams are: