Glaucoma: The Silent Thief of Sight
If caught early, it can be controlled with medicine and surgery
FRIDAY, Jan. 16, 2004 (HealthDayNews) -- It's called the silent thief of sight, and for good reason.
Glaucoma has few if any early symptoms. And when they do appear, the disease has already robbed its victims of some sight. About 3 million Americans have glaucoma, but many do not know it yet.
Regular, routine eye exams, including special tests, can improve the odds of early detection, experts say. And, once detected, the disease can be controlled -- and remaining vision preserved -- with improved medicine and surgery techniques.
"The key is to get checked before the disease becomes symptomatic, " says Dr. Andrew Iwach, an ophthalmologist and assistant professor at the University of California, San Francisco.
That's a message that bears repeating during January, National Glaucoma Awareness Month.
Since glaucoma risk rises with age, eyes should be tested at about age 35 and 40, then every two to four years after age 40 and every one to two years after age 60, suggests the Glaucoma Research Foundation. Those at high risk due to family history should get exams every one to two years after age 35.
Glaucoma is actually a group of eye diseases, but all types damage the optic nerve, causing vision loss and, sometimes, blindness. The optic nerve connects the retina to the brain and it houses more than 1 million nerve fibers. For good vision, you need a healthy optic nerve.
What goes wrong in glaucoma? In the front of the eye, clear fluid flows in and out of a space called the anterior chamber. When the fluid passes out too slowly and builds up, pressure can increase and this intraocular pressure can rise to the point where it damages the optic nerve. This form of the disease, the most common, is called open angle glaucoma. It's so named because the fluid leaves the anterior chamber at the open angle where the cornea and the iris meet.
Some people have glaucoma, and optic nerve damage, even without the pressure within the eye rising -- a type called low-tension or normal-tension glaucoma.
And, in recent years, Iwach says, experts have discovered the thickness of the cornea somehow plays a role in who gets glaucoma.
"We may have a patient who has a higher than normal pressure, but the optic nerve looks fine," he says. Odds are, the patient has a thick cornea, somehow possibly protecting against damage to the nerve.
During an exam for glaucoma, doctors will also look at the optic nerve, measure the intraocular pressure and evaluate peripheral vision -- often affected first in glaucoma.
To lower the pressure inside the eye, drops are commonly prescribed.
"Twenty years ago, in order to control glaucoma, we needed to use drops four times a day," says Dr. Michael Berlin, a professor of clinical ophthalmology at the Jules Stein Eye Institute at the UCLA David Geffen School of Medicine.
Some of the newer eye drop medicines only need to be taken once or twice a day. Drops work either by causing the eye to make less fluid or helping the fluid drain.
If surgery is deemed the best treatment, a doctor may do a procedure called a laser trabeculoplasty, in which the laser is aimed at the lens of the eye and makes several evenly spaced burns, stretching the drainage holes inside the eye and allowing the fluid to escape better.
While the traditional approach has been to use medicine first, then surgery if the glaucoma still progresses, Iwach says the latest thinking has it that some patients may benefit most from having surgery first.
Compliance with medication is a problem among patients, Berlin and Iwach agree. "Most patients are not compliant," Berlin says. Part of the reason, he suspects, is the patient can tell little difference in vision during the short term, whether he takes the medicine or not.
Good patient-doctor communication is the key, say Berlin and Iwach. All the latest information -- whether medicine or laser therapy is best; which eye drops are preferred -- "has to be customized to the individual patient," Iwach says.