June 26, 2003.
By DARLA CARTER,
Tube reduces pressure that damages nerve.
Who's at risk for glaucoma?
The Glaucoma Foundation encourages regular eye exams for people of all ages to detect conditions, such as glaucoma, that can lead to visual impairment and blindness. The foundation says you are at increased risk for glaucoma if you :
Are over 45.
Are of African descent.
Have a family history of glaucoma.
Have abnormally high pressure in your eyes.
Are diabetic .
Have had a prior eye injury.
Have engaged in s teroid/ c ortisone use.
A person with glaucoma typically experiences no obvious symptoms at first but eventually may notice loss of vision from the side, blurred vision and trouble focusing, according to the American Academy of Ophthalmology.
For more information, go to www.glaucomafoundation.org or www.aaog.org.
Eye doctors have another tool to treat glaucoma, an insidious, chronic condition that slowly robs people of their sight before many even know they have it.
The Ex-PRESS glaucoma minishunt is a stainless-steel tube — smaller than a grain of rice — that is implanted in the eye during a five-minute surgical procedure, said Dr. Donald Bennett, a Louisville optometrist and ophthalmologist.
It's designed to reduce pressure in the eye that can damage the optic nerve and lead to vision loss.
The pressure comes from fluid that builds up in the anterior chamber of the eye. The shunt captures the excess fluid and allows it to be diverted away, reducing the pressure.
Bennett said that he and a colleague, Dr. Steven Mattas, were among the first to be certified to perform the procedure, which was approved by the U.S. Food and Drug Administration last year. They've done about 10 of the surgeries since November.
It's "simple to do," Bennett said. "It has very low complications and a very high success rate."
The device can lower pressure by 40 percent after one year and 35.3 percent after two years, according to CIBA Vision, which markets the minishunt. The one-year success rate is 88 percent; the two-year success rate is 83.3 percent.
The device is intended for a minority of glaucoma patients who haven't responded to drops, laser treatment or a trabeculectomy, a type of surgery in which a new drain is made for the eye, Bennett said.
The minishunt is an alternative to receiving a glaucoma valve, which has a higher rate of complications and causes more trauma to the eye, he said.
The patient receives drops to numb the eye before the procedure, stays awake while the surgery is being done and goes home from the hospital the same day.
With the minishunt, "there's not much healing involved," Bennett said. The 1- to 2-millimeter incision is "very small, and that will heal within a few days."
The pressure is often down to where the doctor wants it to be within a couple of days, Bennett said, though the patient may still need to use drops.
High pressure in the eye is a leading risk factor for developing open-angle glaucoma, one of the most common causes of blindness in the United States and the No. 1 cause of blindness among African Americans, according to the National Eye Institute. A national study published last year in the journal Ophthalmology found that glaucoma is also the leading cause of blindness among U.S. Hispanics.
But glaucoma generally can be controlled if detected early enough. The pressure can be measured several ways during a comprehensive eye exam; many people are familiar with the non-contact method in which a puff of air is blown into the eye.
In people with glaucoma, the pressure in the eye often builds up because fluid that continuously flows in and out of the anterior chamber of the eye drains too slowly. Between 3 million and 6 million people are estimated to have problems with high pressure in the eyes and are therefore at risk of developing open-angle glaucoma, according to the eye institute.
Some 2.2 million Americans who have reached age 40 have open-angle glaucoma; an additional 2 million people don't know they have it, according to the institute, because there are no symptoms initially and the vision loss is gradual.
"Typically speaking, the vision is lost very slowly and it's lost from the periphery (side) first, so you don't miss it so much until all of a sudden you realize that you're bumping into things," Bennett said.
The vision loss is permanent, but the minishunt can help to preserve the person's remaining vision, he said. "What we're doing here is we're saving what they've got, which hopefully by this point is still a lot."
The average cost of the procedure is $1,600, and it's generally covered by insurance, according to Bennett & Bloom Eye Centers.
Not everyone is sold on the procedure.
Asim Piracha of John-Kenyon Eye Center said the doctors there shy away from the minishunt for several reasons, including that having a foreign body in the eye may increase the risk of inflammation and infection in patients. Also, the drainage isn't well-controlled, which can lead to excessively low pressure, said Piracha, who specializes in cornea and refractive surgery.
Furthermore, because of the potential for scarring around the shunt, it may not be a permanent fix, Piracha said. "Long-term, we don't know what's going to happen."
To learn more about the minishunt, go to www.cibavision.com or www.eyecenters.com.
For more information about how glaucoma testing is conducted, go to www.nlm.nih.gov/medlineplus/en cy/article/003447.htm.
If you need help getting an eye exam, go to www.eyecareamerica.org to see if you qualify for one of its programs.
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