November 18, 2005.
At first you don't notice a thing. And why should you? Your eyesight seems perfect.
But what you don't know is that the pressure of fluid inside your eyeballs has increased, and is causing damage to your optic nerve.
Still, you don't feel a thing, and your vision isn't affected, so you go about your day-to-day activities, unaware of the danger that lies ahead.
When you finally do realize something is wrong -- you've lost a good deal of your peripheral vision, and are on your way to developing tunnel vision -- it's too late to save the sight that's gone.
Such is the sinister nature of glaucoma, a disease that affects more than 2.2 million Americans over the age of 40, according to the National Institutes of Health.
"The early stages of glaucoma have absolutely no symptoms," said Dr. Mildred M.G. Olivier, president and CEO of the Midwest Glaucoma Center in Hoffman Estates, Ill., and a board member of Prevent Blindness America. "That's why we call it 'the silent thief of sight.' By the time someone feels like something is wrong with their vision, their glaucoma already is very advanced."
October is National Glaucoma Awareness Month and doctors are using those 31 days to urge people to have their eyes checked early and often for signs of the disease.
As many as 120,000 Americans are blind due to glaucoma, according to the National Institutes of Health. Each year, there are more than 300,000 new cases of glaucoma and approximately 5,400 more people suffer complete blindness.
Glaucoma is the common name of a group of diseases that cause damage to the optic nerve, causing blind spots in the victim's visual field. These blind spots usually start in the peripheral vision, but can spread and eventually cause complete blindness in one or both eyes.
"Most people wrongly think of glaucoma as only a disease of high eye pressure," said Dr. Kuldev Singh, a professor of ophthalmology at Stanford University. "It's really the most common optic nerve disease in the world."
Since the disease has no early symptoms, regular screening is the only way to detect and prevent it.
Olivier recommends that people have their ophthalmologist perform a dilated eye examination, so the doctor can take a direct look at the optic nerve and review it for damage.
Other tests include tonometry, in which an instrument measures pressure inside the eye, and pachymetry, in which the doctor uses ultrasonic waves to measure the thickness of your cornea.
Anyone can develop glaucoma, but doctors have identified several key groups of people who have a higher risk of contracting the disease:
Everyone over age 60;
Black people over age 40;
People with a family history of glaucoma;
Those suffering from nearsightedness;
People who have suffered an eye injury or have undergone eye surgery;
People with high blood pressure or diabetes;
Those who must frequently take certain drugs such as steroids.
"If you have any of the risk factors, you're never too young to be screened for glaucoma," Olivier said.
Genetics, in particular, is a strong risk factor that should be taken into account, Singh said. "If you have a family member with glaucoma, you should have yourself screened regularly," he said.
There is no cure for glaucoma, but there are several treatment options that can stem the damage done by the disease. They include medicines, laser trabeculoplasty and surgery.
All of these treatments are aimed at reducing eye pressure, a symptom that accompanies most forms of glaucoma.
"There's only one risk factor that can be treated, and that's eye pressure," Singh said. "So pressure is important in treatment."
Early detection and treatment of increased eye pressure can have a marked affect on the ability to treat glaucoma, he said.
"The studies have overall shown that lowering eye pressure not only decreases the chances of getting glaucoma, but also reduces the likelihood of patients progressing to the point where they suffer symptoms," Singh said.
Medicinal treatments come in the form of eyedrops or pills. Some cause the eye to make less fluid, while others lower pressure by helping fluid drain from the eye, Singh said.
"Early in the course of the disease, medicine is the treatment we prefer," he said.
Laser trabeculoplasty helps fluid drain out of the eye by sending energy waves into the drainage system of the eye, increasing the amount of fluid that naturally seeps from the eye.
Studies have shown that such surgery is good at reducing pressure in some patients, but its effects can wear off over time. Patients often must keep taking glaucoma medicine after treatment, experts say.
Conventional surgery often is done after medicines and laser surgery have failed to control pressure. In the surgery, doctors remove tissue from the eye to create a new drainage channel for fluid.
However, such surgery has its risks. Patients must monitor their eyes for signs of infection, and if the incision accelerates drainage too much, the "eye can collapse," Singh said.
To learn more about glaucoma, visit the U.S. National Library of Medicine.
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