A serious eye disease that usually strikes adults 40 years and older, glaucoma is a degeneration of the optic nerve, usually caused by a build-up of pressure inside the eye. This excessive pressure prevents retinal cells and optic nerve fibers to get the proper blood flow, which causes them to degenerate. Normal pressure ranges are from 14-22. Patients can have elevated eye pressure (ocular hypertension) and never develop glaucoma. Conversely, although it is not fully understood, patients with normal eye pressure can develop glaucoma. This is called normal tension glaucoma. Both types left untreated may lead to severe, irreversible vision loss.
Glaucoma is often called the “sneak thief of sight” because, in its most common form, it progresses gradually before victims realize they’re losing their sight.
Increased pressure inside the eye can lead to vision loss.
The loss of sight starts at the sides and continues toward the center until a small field or “tunnel” of vision remains. People with normal vision can stand at a street intersection and see traffic from both directions. Those with advanced glaucoma can see only straight ahead, as if they were looking through a long tube. Eventually all vision may be lost. Sight lost to glaucoma cannot be restored, but glaucoma can usually be controlled if it is detected in time.
View of the world for a patient who has glaucoma (tunnel vision)
Glaucoma is the leading cause of preventable blindness in the U.S. This year, approximately 67 million people worldwide will suffer from glaucoma. Yet, approximately 2 million Americans don’t even know that they have the disease. Others will be diagnosed only when it’s too late to save vision.
Glaucoma, it should be emphasized, is not an infection. It is not cancer. It is not a drying up of tear ducts. It is not caused by overuse of the eyes. It is, however, a serious disease and one that deserves prompt medical attention. It is not caused by too much reading or too much watching television.
Are You at Risk?
Glaucoma is not contagious, but it does run in families. Higher risk factors include having a sibling with glaucoma, injuring the eye, being severely nearsighted, having various other eye diseases, and taking medications associated with increased incidence of glaucoma.
Glaucoma can be treated and controlled if detected early. Detection of glaucoma requires periodic eye exams with ancillary testing. It is especially important for people over 40 and/or those with any of the higher risk factors explained above.
A Look at Three Types of Glaucoma
Although there are many different varieties of glaucoma, the most common are chronic, primary open angle, normal tension glaucoma, and acute closed-angle glaucoma.
Open Angle Glaucoma
It is by far the most common. It is painless. It slowly destroys vision without warning. By the time a vision problem is noticeable, irreversible damage may have occurred. Chronic glaucoma can be detected through a routine eye exam. Because it is silent and strikes adults, it is important for people over 40 to have a periodic eye exam.
Normal Tension Glaucoma
Although it is not fully understood, normal tension glaucoma can occur in patients with normal eye pressure. It is believed that the optic nerve is deprived of nutrients in the blood, causing its degeneration. Eye pressure is just one bit of data needed to diagnose this disease. Often more than just the pressure test is needed to determine if a patient has glaucoma.
Acute Closed-Angle Glaucoma
Acute closed-angle glaucoma is not very common. It is marked by a sudden, severe pain in and around the eye, sharply decreased vision, headache, nausea and vomiting, and halos around lights. Acute glaucoma causes extremely high pressure, which can lead to blindness in less than 24 hours. To alleviate this pressure, immediate, emergency treatment is required. Surgery or laser treatment may also be necessary to prevent further attacks. For patients in whom a predisposition is detected, laser surgery can prevent an attack from happening.
Diagnosing and Monitoring Glaucoma
At Dr. Farrar’s office we are able to properly diagnose glaucoma if present. But because many of the standard tests are inconclusive for glaucoma at times, we work with local ophthalmologists in situations where glaucoma is suspected but not validated as a condition.
The standard eye pressure check (tonometry) allows us to record eye pressures which can be helpful in detecting glaucoma in many of the patients diagnosed with the disease. Abnormal results with visual field testing (perimetry) don’t show up until after millions of nerve fiber cells have been damaged by glaucoma. However, visual field testing (perimetry) is still the standard method of following glaucoma. This is the test that shows you a series of lights in your peripheral vision.
Watch out for These Warning Signs of Glaucoma
While glaucoma can occur without warning, any one of the following symptoms is possible and warrants a complete eye exam.
- Rainbow colored halos around lights
- Vision narrowed, i.e., loss of side vision
- Frequent changes in prescription glasses without improving vision
- Abnormally poor vision in dim light
- Fuzzy or blurred vision which may come and go
- Headaches, especially after watching TV or movies in the dark
Eye doctors and medical researchers continue to seek better ways to treat and control glaucoma. Their efforts in recent years have led to earlier detection of the disease, new drugs, laser surgery, and more successful surgical techniques.
While chronic glaucoma cannot be cured, it can be controlled chiefly through the use of daily eye drops which either increase fluid removal from the eye or decrease the amount of fluid produced within the eye. Laser surgery is an additional option if the eye medications fail to hold the pressure in check. In more severe cases, surgery may be required to improve the drainage of eye fluids.
Anyone who has glaucoma, who is suspicious of glaucoma, or who has a family history of glaucoma should have one or all of these tests performed. Insurance companies usually cover this new technology. However, the test itself is not very expensive. If you fall in any of the above categories, please call the office and schedule a complete eye examination.