GLAUCOMA IS AN EYE DISEASE that can cause blindness. If caught early, it can usually be treated and controlled. Because glaucoma often has no symptoms, however, it is important to have yearly eye exams. Glaucoma begins when pressure builds up in the eye. This intraocular pressure can damage the optic nerve, which sends messages to the brain so we can see.

Glaucoma is the second most common cause of blindness in the United States. African-Americans over the age of 40 and everyone over 60, especially Mexican-Americans, are at risk. For adults over 60, it is the leading cause of blindness.

The front of the eye is filled with the aqueous humor, a clear fluid made in an area behind the iris. It leaves the eye through channels where the iris and cornea meet called the anterior chamber angle. The cornea is the clear substance that covers the iris, pupil and angle.

Anything that slows or blocks the flow of this fluid causes pressure to build, resulting in one of four types of glaucoma: open angle, angle closure or closed angle, congenital and secondary. In open angle glaucoma, the increase in pressure is small and slow. In angle closure, the increase is often high and sudden. Either type can damage the optic nerve.

Open angle glaucoma is the most common type and tends to run in families, though the cause is unknown. Your risk is higher if you have a parent or grandparent with open angle glaucoma. The pressure increases slowly over time and you cannot feel it. The increased pressure pushes on the optic nerve. Damage to the optic nerve causes blind spots in your vision. Most people have no symptoms with open angle glaucoma. Once vision loss occurs, the damage is already severe. The individual experiences a slow loss of side peripheral vision, a phenomenon known as tunnel vision. Advanced glaucoma can lead to blindness.

Angle closure glaucoma occurs when the fluid is suddenly blocked from flowing out of the eye, causing a quick, severe rise in pressure. Symptoms come and go at first or steadily become worse. You may notice sudden severe pain in one eye, decreased or cloudy vision (steamy vision) and nausea and vomiting. Other symptoms include rainbowlike halos around lights, red eye and eyes that feel swollen. Dilating eye drops and certain medications may trigger an acute glaucoma attack. If you had acute glaucoma in one eye, you are at risk for it in the second eye. Your ophthalmologist will likely treat your second eye to prevent a sudden attack in that eye.

Both open angle and angle closure glaucoma can be secondary when the cause is known. Causes include drugs such as corticosteroids, eye diseases such as uveitis (an infection in the middle layer of the eye), diseases such as diabetes, and eye injury. Secondary glaucoma presents symptoms often related to the underlying problem; depending on the cause, symptoms may either be like open or closed angle glaucoma.

Congenital glaucoma is present at birth and is caused when the eye does not develop normally. It often runs in families. Symptoms are most often noticed when a child is a few months old and include cloudiness of the front of the eye, enlargement of one eye or both eyes, red eye, sensitivity to light and tearing.

The only way to diagnose glaucoma is with a complete eye exam including a test to check eye pressure. In most cases, eye drops will dilate (widen) your pupil so the ophthalmologist can look inside your eye and at the optic nerve. Eye pressure varies at different times of the day; it can even be normal in some people with glaucoma. Your doctor may administer other tests to confirm glaucoma such as using a special lens to look at the angle of the eye, optic nerve imaging, checking your retina, checking how your pupil responds to light, 3D views of the eye, visual acuity testing and visual field measurement.

The goal of treatment is to reduce eye pressure and depends on the type of glaucoma. If you have open angle glaucoma, you will probably use drops but may also need pills to lower pressure. If the drops do not work, you may require laser treatment to open the channel. If laser does not work, surgery may be required to release the fluid.

An acute closed angle attack is a medical emergency. If you have severe eye pain or sudden loss of vision, get immediate medical help. You can become blind in a few days if not treated. You may be treated with eye drops, pills and intravenous medication to lower your pressure. Some people require emergency eye surgery called an iridotomy, which uses a laser to open a new channel in the iris. The new channel relieves the attack and prevents another attack. To prevent an attack in the other eye, the procedure is often performed on that eye.

With secondary glaucoma, treating the cause may help symptoms go away. Other treatments may be needed. Congenital glaucoma is almost always treated with surgery, usually performed with general anesthesia. Babies with congenital glaucoma do well when surgery is done early.

You can keep your eyesight by following your eye doctor’s directions. To prevent vision loss, have regular, complete eye exams as recommended by your ophthalmologist; she can find glaucoma early, when it is easiest to treat. All adults should have an exam by age 40. If you are at risk for glaucoma, have your eye exam earlier.

The content of this article is for informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition.