Glaucoma is a condition in which the eye's intraocular pressure (IOP) is too high. This means that your eye has too much aqueous humor in it, either because it produced too much, or because it's not draining properly. Other symptoms are optic nerve damage and vision loss.

In glaucoma, eye pressure plays a role in damaging the delicate nerve fibers of the optic nerve. When a significant number of nerve fibers are damaged, blind spots develop in the field of vision. Once nerve damage and visual loss occur, it is permanent. Most people don't notice these blind areas until much of the optic nerve damage has already occurred. If the entire nerve is destroyed, blindness results.

Elevated pressure in the eye is the main factor leading to glaucomatous damage to the eye (optic) nerve. Glaucoma with normal intraocular pressure is discussed below in the section on the different types of glaucoma. The optic nerve, which is located in back of the eye, is the main seeing nerve for the eye. This nerve transmits the images we see back to the brain for interpretation.

In angle-closure glaucoma, the normal drainage canals within the eye are physically blocked. Angle-closure glaucoma can be acute (sudden) or chronic (long-lasting). In acute angle-closure glaucoma, a sudden increase in IOP occurs because of the buildup of fluid known as aqueous humor. Acute angle-closure glaucoma is considered an emergency because optic nerve damage and vision loss can occur within hours of the onset of the problem. Chronic angle-closure glaucoma may cause vision damage without symptoms.

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 Intra-Ocular Pressure (IOP) remains in the normal range.

Glaucoma can affect anyone, but some groups are at increased risk for contracting the disease. Those with high pressure in the eyes are more likely to suffer from glaucoma. Individuals over age 40, persons with diabetes, women, those with nearsightedness or high blood pressure, and those of African descent may be at increased risk. A family history of glaucoma also indicates increased likelihood of contracting it. Those at risk for glaucoma should seek more facts and information about the disease by contacting a doctor.

Symptoms

There are usually no noticeable symptoms of open-angle glaucoma. The loss of vision occurs very slowly, often over a period of years. If only one eye is affected, the other eye takes over the task of seeing for both eyes. The person with glaucoma does not realize that vision is being affected. Eventually, however, loss of vision becomes severe. The patient becomes aware that a problem exists. By this time, the glaucoma is more difficult to treat.