Lakewood, NJ – Glaucoma is a group of eye diseases which gradually steals sight without warning, and often without symptoms. Vision loss is caused by damage to the optic nerve. The optic nerve acts like an electric cable with over a million wires and is responsible for carrying images we see to the brain.
According to Richard Angrist, MD, Chief of Ophthalmology at Kimball Medical Center, intraocular pressure (IOP) was once thought to be the main cause of this optic damage. “IOP is a risk factor, but other factors are also involved because even people with normal IOP can experience vision loss from glaucoma,” he explains.
Glaucoma affects an estimated three million Americans, 120,000 of whom are blind as a result. Glaucoma ranks as one of the leading causes of blindness throughout the world. Even if those with glaucoma do not become blind, their vision can be severely affected. About half of all Americans with glaucoma do not even know they have it. Glaucoma is a chronic disease which must be treated for life. Currently, its causes are not well understood and there is no cure.
“The eye has pressure just as our blood does, and when this intraocular pressure increases to dangerous level, it damages the optic nerve,” says Dr. Angrist. “This can result in decreased vision and eventually, blindness.”
There are two main types of glaucoma: open angle glaucoma and closed angle glaucoma.
Primary open-angle glaucoma gradually reduces your vision, and can go on for years before you notice any loss in sight. This type of glaucoma develops when there is a blockage deep within your eye’s drainage canal. This blockage causes the IOP to rise because the fluid in the eye can not drain properly. Closed angle glaucoma, also known as acute glaucoma or narrow angle glaucoma, is rare and is very different from open angle glaucoma in that the eye pressure usually rises very quickly. This happens when the drainage canals get blocked or covered over. Symptoms may include headaches, eye pain, nausea, rainbows around lights at night, and very blurred vision.
Through a visit to an ophthalmologist, you can be screened for this specific pattern of optic nerve damage. “The most important thing you can do to protect your vision from glaucoma is to have regular eye exams,” says Dr. Angrist. “If your ophthalmologist finds that you have the disease or that you are at risk, he or she can recommend treatment to minimize the risks or the effects.”
Normal Tension Glaucoma (NTG)
Normal tension glaucoma is also known as low-tension glaucoma or normal pressure glaucoma. In this type of glaucoma, the optic nerve is damaged even though intraocular pressure (IOP) is not very high. Doctors do not know why some people’s optic nerves suffer damage even though pressure levels are in the “normal” range (between 12-22 mm Hg).
Those at higher risk for this form of glaucoma are people with a family history of normal tension glaucoma, people of Japanese ancestry, and people with a history of systemic heart disease, such as irregular heart rhythm. Normal tension glaucoma is usually detected after an examination of the optic nerve.
The Glaucoma Research Foundation sponsored a collaborative international study to help determine the best treatment for this type of glaucoma. The study concluded that eye drops used to lower intraocular pressure were effective even in cases of normal tension glaucoma. Currently, most doctors treat normal tension glaucoma by keeping normal eye pressures as low as possible with medicines, laser surgery, or filtering surgery.
Read more about Normal Tension Glaucoma.
Pediatric Glaucoma
The pediatric glaucomas consist of congenital glaucoma (present at birth), infantile glaucoma (appears during the first three years), juvenile glaucoma (age three through the teenage or young adult years), and all the secondary glaucomas occurring in the pediatric age group.
Congenital glaucoma is present at birth and most cases are diagnosed during the first year of life. Sometimes symptoms are not recognized until later in infancy or early childhood.
The range of treatment is very different from that for adult glaucoma. It is very important to catch pediatric glaucoma early in order to prevent blindness.
Read more about childhood glaucoma.
Primary Open Angle Glaucoma
This is the most common form of glaucoma, affecting about three million Americans. It happens when the eye’s drainage canals become clogged over time. The inner eye pressure (also called intraocular pressure or IOP) rises because the correct amount of fluid can’t drain out of the eye. With open angle glaucoma, the entrances to the drainage canals are clear and should be working correctly. The clogging problem occurs further inside the drainage canals, similar to a clogged pipe below the drain in a sink.
Most people have no symptoms and no early warning signs. If open angle glaucoma is not diagnosed and treated, it can cause a gradual loss of vision. This type of glaucoma develops slowly and sometimes without noticeable sight loss for many years. It usually responds well to medication, especially if caught early and treated.
Secondary Glaucoma
Glaucoma can occur as the result of an eye injury, inflammation, tumor or in advanced cases of cataract or diabetes. It can also be caused by certain drugs such as steroids. This form of glaucoma may be mild or severe. The type of treatment will depend on whether it is open angle or angle closure glaucoma.
Pseudoexfoliative Glaucoma
This form of secondary open angle glaucoma occurs when a flaky, dandruff-like material peels off the outer layer of the lens within the eye. The material collects in the angle between the cornea and iris and can clog the drainage system of the eye, causing eye pressure to rise.
Pseudoexfoliative Glaucoma is common in those of Scandinavian descent. Treatment usually includes medications or surgery.
Pigmentary Glaucoma
A form of secondary open angle glaucoma, this occurs when the pigment granules in the back of the iris (the colored part of the eye) break into the clear fluid produced inside the eye. These tiny pigment granules flow toward the drainage canals in the eye and slowly clog them, causing eye pressure to rise. Treatment usually includes medications or surgery.
Read more about pigmentary glaucoma.
Traumatic Glaucoma
Injury to the eye may cause secondary open angle glaucoma. This type of glaucoma can occur immediately after the injury or years later.
It can be caused by blunt injuries that “bruise” the eye (called blunt trauma) or by injuries that penetrate the eye.
In addition, conditions such as severe nearsightedness, previous injury, infection, or prior surgery may make the eye more vulnerable to a serious eye injury.
Read more about traumatic glaucoma.
Neovascular Glaucoma
The abnormal formation of new blood vessels on the iris and over the eye’s drainage channels can cause a form of secondary open angle glaucoma.
Neovascular glaucoma is always associated with other abnormalities, most often diabetes. It never occurs on its own. The new blood vessels block the eye’s fluid from exiting through the trabecular meshwork (the eye’s drainage canals), causing an increase in eye pressure. This type of glaucoma is very difficult to treat.
Irido Corneal Endothelial Syndrome (ICE)
This rare form of glaucoma usually appears in only one eye, rather than both. Cells on the back surface of the cornea spread over the eye’s drainage tissue and across the surface of the iris, increasing eye pressure and damaging the optic nerve. These corneal cells also form adhesions that bind the iris to the cornea, further blocking the drainage channels.
Irido Corneal Endothelial Syndrome occurs more frequently in light-skinned females. Symptoms can include hazy vision upon awakening and the appearance of halos around lights. Treatment can include medications and filtering surgery. Laser therapy is not effective in these cases.
To schedule an eye exam with Dr. Angrist or another ophthalmologist on staff at Kimball Medical Center, call the Barnabas Health Care Link at 1-888-724-7123.
Date: December 29, 2009
CONTACT: Carrie Cristello
Director, Public Relations
732-923-6552
ccristello@barnabashealth.org
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