by Paulette Avery, R.N., M.S.N., I.B.C.L.C.

If asked which sense you would most hate to lose, you'd most likely say your vision. With that in mind, I'm focusing this month's column on glaucoma, which, after cataracts, is the second most common cause of blindness in the world. An estimated four million Americans have glaucoma, yet as many as half of them are unaware they do. Read on to learn what glaucoma is, how it is diagnosed, and what can be done to treat it.

Glaucoma results most commonly when too much fluid pressure builds up in the eye. The pressure, called intraocular pressure or IOP, causes damage to the ocular nerve and can lead to irreversible blindness. Normally, fluid drains out of the eye through a meshlike channel. For unknown reasons, this channel becomes blocked in some people, leading to the most common type of glaucoma called open-angle. In the less common narrow-angle glaucoma, also known as angle-closure glaucoma, pressure builds as a result of an anatomical narrowing of the angle between the iris and the cornea. Both types of glaucoma tend to run in families, so if one or both of your parents have glaucoma, it is more likely that you will too.

Eye pressure from glaucoma usually increases without any pain or other early warning signs, so the best way to protect your vision is to get your eyes examined every one or two years. Fortunately, your eye doctor can diagnose glaucoma easily using simple tests to measure the pressure in the eyes. Glaucoma most commonly occurs after the age of 40, but can occur at any age. Any of the following put you at greater risk for developing glaucoma: age over 40; being of African American, Irish, Russian, Hispanic, Japanese, Inuit, or Scandinavian descent; having a family history of glaucoma; having poor vision; having diabetes; or taking corticosteroid medications, such as Prednisone.

Treatment depends on the type of glaucoma. Prescription eye drops are often the first choice for the more common open-angle glaucoma. The drops work by either reducing the formation of fluid in the eye or increasing flow out of the eye. Laser or microsurgery may be used to open up the drainage area for open-angle glaucoma or to eliminate the blockage of fluid in narrow-angle glaucoma. Your doctor may recommend preventive laser surgery if you have narrow angles even if your eye pressures are normal. That is because it is not known when or if narrow-angle glaucoma may develop. When it does occur, it tends to happen suddenly causing severe eye pain, headaches, and/or visual problems, and if not treated promptly, results in blindness. For treatment or prevention, a laser is used to create a small hole in the iris, usually in the area under the upper eyelid, allowing better fluid drainage from the eye.'

Although no cure currently exists for glaucoma, it can be controlled with appropriate treatment. So remember to get your eyes checked regularly.

Paulette Avery is a registered nurse and a freelance writer who specializes in health issues.