Definition

Glaucoma is a general term that refers to a group of conditions that lead to progressive damage to the optic nerve. People with primary open angle glaucoma, by definition, have normal open anterior chamber angles and no other underlying disease. It is often called the “sneak thief of sight” because there are no symptoms until late in the disease. Once vision is lost to glaucoma, it cannot be restored but blindness can be prevented with early detection and treatment. Glaucoma is a chronic disease and proper treatment requires long-term care.

How Common is it? Glaucoma is the second leading cause of blindness in the US and affects about 2.5 million Americans. Up to half of those with glaucoma don’t know they have it!

How the Eye Works The eye functions as a camera, capturing information about the surrounding world and relaying it to the brain through the optic nerve. The front part of the eye is filled with a clear fluid called aqueous humor. After circulating, the aqueous humor it leaves the eye through a microscopic drainage system located in the anterior chamber angle and is eventually absorbed into the bloodstream. In a healthy eye with a normal level of pressure, the aqueous is slowly produced and drained at the same rate.

What Causes Open Angle Glaucoma? In primary open angle glaucoma, the drainage angle for the aqueous humor becomes blocked. The excess fluid cannot flow out of the eye and the fluid pressure or “intraocular pressure” increases. The high pressure pushes against the delicate nerve fibers in the optic nerve causing damage. As optic nerve fibers become damaged and die, the nerve develops a caved-in or “cupped” shape.

What Role Does Intraocular Pressure Play? Elevated intraocular pressure is an important risk factor for glaucoma but is not the entire story. Other factors must be involved since not everyone with high pressure gets glaucoma and some people with normal pressure suffer nerve damage and vision loss (called normal tension glaucoma, a form of open angle glaucoma)

There are Four Main Types of Glaucoma
• Primary Open Angle Glaucoma (includes normal tension glaucoma)
• Narrow Angle or Angle-closure Glaucoma
• Congenital Glaucoma • Secondary Glaucoma

What are the Risk Factors for Primary Open Angle Glaucoma?
• Age • Intraocular Pressure
• African-American Heritage
• Family History
• Myopia for nearsightedness
• Diabetes or Cardiovascular Disease

Is it hereditary? Primary open-angle glaucoma tends to run in families. Your risk is higher if you have a parent or sibling with open-angle glaucoma. People of African descent are at a higher risk, tend to be affected at a younger age, and are more likely to loss sight from the disease. Anyone with a family history of glaucoma should be checked often - every year or two after age 40.

What are the Symptoms for Primary Open Angle Glaucoma? In the early stages of the disease there are no symptoms and vision is normal. If glaucoma damage continues blind spots develop, typically in the peripheral or side vision first. Over time, tunnel vision develops. Eventually, the last bit of central vision is lost

How is Glaucoma Detected?
Regular thorough eye examinations are the best way to detect glaucoma. A simple intraocular pressure check is not enough, however. A thorough eye examination should also include a test of your field of view and documentation of the appearance of your optic nerves. Remember, high pressure means higher risk for glaucoma but a normal pressure is not a clean bill of health.

• Tonometry

- Numbing drops are instilled in the eye and an instrument is briefly touched to the surface of your cornea to measure the pressure. It is a painless test that only takes a few seconds. • Perimetry

- Perimetry is a computerized test of your visual field and is used to monitor your peripheral or side vision. It takes approximately 5 minutes per eye.

• Optic Nerve Documentation - It is very important for your doctor to document the appearance of your optic nerve in order to see if there are changes over time. One way is to take a photograph. Another is to take a computerized image. There are several commercially available imaging systems which, depending on the instrument, will capture a slice of the nerve (like an MRI) or a 3-D map of the nerve to use for future comparison.

Who Gets Treated? One examination may not be enough to diagnosis glaucoma. Your doctor may use the term “glaucoma suspect” if there are some signs for glaucoma but not others. In this case, you may need to be monitored to see if any changes occur over time. Many factors are taken into account before deciding about treatment.

Glaucoma Treatment Damage caused by glaucoma is permanent. The goal of treatment is to reduce intraocular pressure and stabilize optic nerve damage to prevent further loss of vision. Drops, laser, or surgery are used to lower intraocular pressure (a modifiable risk factor) Your doctor may choose a target pressure – a range of intraocular pressures where further nerve damage is deemed unlikely (specific for each patient). • Medication or drops are typically the first line of treatment. They work by decreasing aqueous production and/or increasing aqueous drainage. Most are dosed 1-3 times per day. As with any medication, side effects may occur. • Laser surgery increases outflow of aqueous humor. It is an in-office procedure that takes about 5 minutes and works well in about 75% of people. Laser surgery is not a cure, however – drops may still be necessary after the procedure and the effect may wear off over time. • The purpose of glaucoma surgery is to create a new opening for the aqueous humor to drain out of the eye. Typically performed in an operating room as an outpatient procedure, it often results in a dramatic reduction in intraocular pressure. As with any surgery, there is a recuperation period and complications can occur.

Anyone who falls into one or more of these categories should talk with an eye doctor. If you or someone you know may be at risk for glaucoma, call 610-690-4900 today or click here to schedule an appointment.