Encyclopedia - Glaucoma

What is glaucoma?
How many are affected by glaucoma?
What causes glaucoma?
What are the symptoms of glaucoma?
How is glaucoma detected?
What are the treatments for glaucoma?
What are the forms of glaucoma?

What is glaucoma?

Glaucoma is a very evasive and dangerous eye disease. It can happen to people without their knowledge and can cause partial, sometimes, total blindness. In fact, glaucoma is the second leading cause of blindness in the United States.

In simple terms, glaucoma is caused by the excessive buildup of fluid inside the eye. Eyes are essentially hollow globes filled with a constantly circulating clear fluid that must drain out of the eye as more is pumped in. Each eye produces about 4 c.c. of fluid a day, a considerable amount for an object that is only about 1 inch in diameter.

Sometimes the eye’s drainage system becomes clogged, causing pressure in the eye to build up to damaging levels. Unless controlled, damage to the optic nerve and loss of vision can occur. The earliest sign of optic nerve damage is often a loss of peripheral (side) vision. However, the early onset of glaucoma can be detected not by any symptoms but by a comprehensive eye exam and specific glaucoma tests.

How many are affected by glaucoma?

The most common form of glaucoma is called open-angle glaucoma. It is so named because the angle from which the fluid drains out of the anterior chamber is open. This form of glaucoma affects approximately 3 million Americans. Glaucoma occurs in nearly 1 to 2 percent of people over the age of 40.

What causes glaucoma?

There is no single cause of glaucoma. Anyone can develop glaucoma, but generally, those at higher risk than the average population are:

People more than 60 years of age
African Americans over the age of 40
People with a family history of glaucoma

What are the symptoms of glaucoma?

Only an eye care professional can determine whether or not a person has glaucoma and how severe it is. Glaucoma begins without showing any symptoms. If it remains untreated and undetected, a person may notice a loss of peripheral vision and the start of tunnel vision. Gradually, sight diminishes completely. A few glaucoma sufferers have such early symptoms as severe eye pain, blurred vision, seeing halos around lights, and constantly dilated pupils, though these are the exceptions.

Note that experiencing these symptoms does not necessarily signal glaucoma. Patients with any changes in their vision or optical comfort should see an eye care professional for a thorough evaluation.

How is glaucoma detected?

Detection is vital. For patients, understanding glaucoma helps in both treatment and long-term eye care. Pressure is key. Glaucoma can occur in eyes with "normal" pressure readings, though "normal" pressure varies from person to person. The pressure’s effect on, or the potential risk to, the optic nerve determines the severity of glaucoma.

To determine whether a person has glaucoma, an eye care professional conducts several tests. A tonometry test measures the amount of pressure on the optic nerve and is usually part of every complete eye exam.

A popular tonometry test is often referred to as the "air-puff" test. The patient looks through a machine as it blows a puff of air at the eye.

Another form of tonometry, and one of the most accurate, uses a contact tonometer, an instrument that looks like a pen. After numbing eye drops are administered, the tip of the tonometer touches the eye and measures the pressure.

As a general guideline, pressure above 21 millimeters is considered to be elevated, though not all persons with that reading will have glaucoma. Eye care professionals will carefully monitor pressures for early signs of glaucoma.

Another test used in detection is an examination of the optic nerve, looking at the interior of the eye to detect any damage. A pupil dilation test provides the eye care professional to get a better look at the inner eye. A visual acuity test helps to evaluate peripheral vision.

What are the treatments for glaucoma?

Medication

The first line of treatment is often the use of eye drops administered three times per day or oral medication to help drain the fluid and lower pressure. Sometimes eye drops or pills are enough to lower pressure. As with all medications, it is important to give the eye care professional a complete history of current medications, allergies or any other side effects experienced from the medication. Following the eye drops and oral medication directions closely is equally important.

Laser surgery

When pressure can not be lowered adequately or side effects are too severe, eye care professionals turn to laser treatment as the next, and necessary, treatment. Laser surgery uses focused light to reopen the drainage area to alleviate the buildup of fluid. After receiving a numbing agent in the eyes, patients sit facing the laser machine, while the eye care professional gently holds a lens used to aim the laser beam to the eye. A beam of light hits the eye’s lens and reflects into the drainage area of the eye. The entire procedure usually takes only minutes.

Generally, there are no restrictions following laser surgery, but patients are given eye medications to use for a few days after the procedure. Eye care professionals will continue to monitor pressure closely and regularly. Some consider laser surgery a temporary method to reducing pressure. Studies indicate that the effects of laser surgery diminish over time. More than half of all patients undergoing laser surgery show pressure increases in just two years after surgery.

Conventional surgery

Conventional surgery for glaucoma involves making an incision in the eye to create a new drainage path. The eye tissue creates a new area for fluid to drain naturally. Patients cannot feel this draining. The procedure takes about 10 to 15 minutes. Eye medication is used to prevent infection. This surgery typically requires close follow-up and a lot of care afterward. Studies on the effect of surgery indicate that 80 percent to 90 percent of patients have lowered pressure readings after the surgery. However, there is no cure for glaucoma. Surgery may save remaining vision but it can not improve sight that has already been impaired or lost.

What are the forms of glaucoma?

There are many types of glaucoma. Open-angle glaucoma is the most common. All are similar because they relate to an increase or a buildup of pressure inside the eye.

Angle-closure or closed-angle glaucoma is characterized by intense pain, starting with a headache and including such other symptoms as nausea, red eye, and blurred vision. Angle-closure glaucoma can occur all at once and be severe, or gradually in small episodes. Both of these types require immediate medical attention.

Secondary glaucoma occurs as a result of some other medical problem with the eye, such as inflammation, injury, advanced cataracts, or certain tumors. Congenital glaucoma occurs in children born with malformations in the angle of the eye. Usually, parents detect symptoms, such as eyes that appear cloudy, severe sensitivity to light, and excessive tearing or watery eyes. Many eye care professionals recommend surgery over eye drops, because of the difficulty of administering drops in infants and the unknown effects of the drops on young eyes. Surgery on children usually results in adequate vision.

Because of the many unknown factors surrounding glaucoma, research is focusing on ways to service patients with the disease. Patients with questions or concerns regarding glaucoma should contact their eye care professional or a professional organization dedicated to glaucoma research.