Glaucoma

Your eye has pressure just like your blood, and when this intraocular pressure (IOP) increases to dangerous levels, it damages the optic nerve. This can result in decreased peripheral vision and, eventually, blindness. Glaucoma is similar to ocular hypertension but with accompanying optic nerve damage and vision loss.

There are two major types of glaucoma: chronic or primary open-angle glaucoma (POAG) and acute closed-angle glaucoma. Other variations include congenital glaucoma, pigmentary glaucoma and secondary glaucoma.

Signs of Glaucoma

Chronic glaucoma (primary open-angle glaucoma or POAG) is often called "the silent thief of sight" because you have no warning sign, no hint that anything is wrong. About half of Americans with chronic glaucoma don't know they have it. Glaucoma gradually reduces your peripheral vision, but by the time you notice it, permanent damage has already occurred. If your IOP remains high, the destruction can progress until tunnel vision develops, and you will only be able to see objects that are straight ahead.

Other signs include headaches, blurred vision, difficulty adapting to darkness, or haloes around lights. Chronic glaucoma normally develops after age 35.

Like POAG, normal-tension glaucoma (also termed normal-pressure glaucoma, low-tension glaucoma or low-pressure glaucoma) is an open-angle type of glaucoma that can cause visual field loss due to optic nerve damage, but in normal-tension glaucoma, the eye's IOP remains in the normal range.

Chronic narrow-angle glaucoma, like open-angle glaucoma, can be symptomless until vision loss occurs.

An acute attack of narrow-angle glaucoma, also termed acute angle-closure glaucoma or acute closed-angle glaucoma, produces sudden symptoms such as eye pain, headaches, haloes around lights, dilated pupils, vision loss, red eyes, nausea and vomiting. These signs may last for a few hours, then return again for another round. Each attack takes with it part of your field of vision.

Acute angle-closure glaucoma is a medical emergency. If the high pressure is not reduced within hours, it can permanently damage vision. Anyone who experiences its symptoms should immediately contact an ophthalmologist or go to a hospital emergency room.

Treatment

The best way to prevent vision loss from glaucoma is early diagnosis and treatment. See your eyecare practitioner at least every two years for a complete examination, including an IOP check. People at high risk for glaucoma due to high intraocular pressures, family history, ethnic background, age or optic nerve appearance may need more frequent visits to the eye doctor.

A test called a visual field may be performed on glaucoma suspects to detect peripheral vision loss. It involves staring straight ahead into a machine and clicking a button when you notice a blinking light in your peripheral vision. The visual field test may be repeated at regular intervals for your doctor to determine the extent of vision loss.

Glaucoma treatment (for any form) entails decreasing aqueous humor production, increasing fluid drainage or a combination of the two. These treatments will not restore any vision already lost to glaucoma.

Most cases of glaucoma can be controlled with a single drug or drug combinations, but some patients may require or select surgery. About 70% of patients need new or extra medications within two years after the start of drug treatment. That's compared with 56% of those who choose laser surgery.

During a type of glaucoma surgery called trabeculoplasty, the doctor uses a laser to create tiny holes where the cornea and iris meet, to increase aqueous humor drainage. Another procedure called trabeculectomy creates an artificial drainage area; it's used in cases of advanced glaucoma where there is optic nerve damage and the IOP continues to soar. A third option is a drainage device, which the surgeon implants in your eye to improve fluid drainage.

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