|John E. Meehan
What is glaucoma?
Glaucoma is a group of diseases that can damage the eye's optic nerve and result in vision loss and blindness. Glaucoma occurs when the normal fluid pressure inside the eyes slowly rises. 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.
NarrowAngle Glaucoma (NAG) is a less common type of glaucoma. Although it is curable by laser iridotomy, it is imperative that these patients continue to be monitored, as many of them will also, eventually, develop open angle glaucoma. No drops are used in treating this type of glaucoma. Laser iridotomy, a 60-second procedure is employed to cure narrow angle glaucoma. This procedure has been available for 25 years and can be performed using either the Argon or the YAG laser.
Open Angle Glaucoma (OAG - by far the most common type of glaucoma) is controllable, but not curable. It is a chronic (i.e., forever) and progressive (i.e., it gets worse with age) condition. As such, it must be monitored regularly and retreated throughout life. The new SLT laser, unlike the traditional Argon laser, allows for re-treatment in the future as the glaucoma progresses with age.
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. (See diagram below.) 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.
Can 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 glaucoma?
Anyone can develop glaucoma. Some people are at higher risk than others. They include:
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.
Medicare covers an annual comprehensive dilated eye exam for some people at high risk for glaucoma.
SYMPTONS AND DETECTION
What are the symptoms of glaucoma?
At first, there are no symptoms. Vision stays normal, and there is no pain.
However, as the disease progresses, a person with glaucoma may notice his or her side vision gradually failing. That is, objects in front may still be seen clearly, but objects to the side may be missed.
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.
How is glaucoma detected?
Glaucoma is detected through a comprehensive eye exam that includes:
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.
The SLT laser is considered very safe and because it is not associated with permanent scarring of the draining system, it will be replacing the argon laser procedure (ALT) as the primary treatment modality for open angle glaucoma. Unlike its argon laser predecessor, the SLT can be used to treat essentially any patient with open angle glaucoma (OAG): i.e.,
There are only two other facilities in the area capable of providing the SLT laser technology: one in Providence and the other at the Massachusetts Eye and Ear Infirmary in Boston. Appointments with Dr. Sullivan for evaluation as to appropriateness of SLT treatment may be scheduled by calling his office at 508-994-1400 or 508-823-5536.
Conventional Surgery. Glaucoma surgery has been available for over 50 years, but has been reserved as a last resort in patients who are still losing vision despite the use of multiple drops and laser treatments. Glaucoma surgery though successful and often necessary carries a higher risk than the use of either drops or laser.Conventional surgery makes a new opening for the fluid to leave the eye.