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Glaucoma does not always exhibit symptoms

As the human body ages, certain things might not work as well as they used to. Though no two individuals are the same, there are certain things people expect to deal with as they age.

Changes in vision are one thing many people associate with aging. Some people maintain perfect vision throughout their lives, while others' vision deteriorates and conditions begin to develop. Though not exclusive to the elderly, glaucoma is one such condition many seniors must deal with. But even though risk for glaucoma increases as a person ages, that doesn't mean younger men and women should not familiarize themselves with this condition and learn its symptoms and characteristics. In fact, glaucoma can be present for years before it's recognized. This only further highlights the importance of understanding this condition so, should it appear, it can be effectively treated as soon as possible.

What is glaucoma?

Glaucoma is a term used to refer to a group of conditions that can cause damage to the optic nerve. The optic nerve is responsible for carrying visual information from the eye to the brain, and oftentimes optic nerve damage is a result of increased pressure in the eye. In the United States, glaucoma is the second most common cause of blindness. In Canada, the Glaucoma Research Society of Canada reports that more than 400,000 Canadians have glaucoma today.

What role does intra-ocular pressure play?

The eyes are filled with fluids that help maintain pressure in the eye. That pressure is called intra-ocular pressure, or IOP. IOP is not a bad thing, but high IOP is a risk factor for glaucoma. Measuring IOP is fairly easy. Doctors will use a tonometer to measure IOP, but men and women should know that normal IOP does not necessarily mean a person does not have glaucoma, nor does high IOP mean a person does have glaucoma. While high IOP is a risk factor for glaucoma and controlling IOP is a focus of glaucoma therapy, there is more to diagnosing and treating glaucoma than just focusing on IOP.

What causes high IOP?

The eye produces a fluid called the aqueous humor which is used to bathe and nourish the various parts of the eye. This fluid typically flows out of the eye through channels in the front of the eye in an area called the anterior chamber angle. When the flow of the aqueous humor is blocked or slowed, the fluid gets trapped in the eye and then IOP builds, at which point damage to the optic nerve can occur.

Are all cases of glaucoma the same?

Not all cases of glaucoma are the same. In fact, there are four major types of glaucoma.

* Open-angle, or chronic, glaucoma: Open-angle glaucoma is the most common type of glaucoma. The cause is unknown, but an increase in eye pressure occurs slowly over time as the pressure starts to push on the optic nerve and the retina at the back of the eye. This type of glaucoma tends to run in families, so men and women who have a parent or grandparent who has had open-angle glaucoma should not miss appointments with his or her eye doctor, even if vision seems normal. This is especially important because most people with open-angle glaucoma have no symptoms until they begin to lose vision, though gradual loss of peripheral vision may occur.

* Angle-closure, or acute, glaucoma: Angle-closure glaucoma occurs when the aqueous humor is suddenly blocked. This is very noticeable, as it causes instant and severe pain as the IOP quickly increases. Risk for angle-closure glaucoma increases for those who have already had it one eye. Symptoms include decreased or cloudy vision, nausea and vomiting, seeing rainbow-like halos around lights, and reddening of the eye.

* Congenital glaucoma: Congenital glaucoma is present at birth and results from an abnormal development of the fluid outflow channels in the eye. Symptoms are typically noticed when the child is a few months old. These can include cloudiness of the front of the eye, enlargement of one or both eyes, sensitivity to light, tearing, and reddening of the eye.

* Secondary glaucoma: Secondary glaucoma results from other conditions, including uveitis, a condition where the middle layer of the eye, known as the uvea, swells and causes irritation. Secondary glaucoma can also result from systemic diseases and drugs such as corticosteroids.

More information about glaucoma is available at the Glaucoma Research Society of Canada Web site at