Corneal Rings:
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10kwizard.ragingbull.com
Corneal Rings An Alternative To Laser Surgery
For more than three years, 20 million mildly nearsighted Americans have been caught in a dilemma: Stick with glasses and contacts, or pay for popular new laser surgery to fix their vision.
Nearly a million a year opt for surgery. But, many others still feel skittish about the risks and permanence of laser procedures. Now, they have a third choice, say doctors at the University of Michigan Health System.
The new procedure, available at the U-M's Kellogg Eye Center and other select locations since early 1999, fixes eyesight by implanting a tiny plastic ring into each eye. After several months of seeing the results for themselves, U-M eye surgeons say the quick, effective and reversible operation could provide a needed alternative for about half of all nearsighted people.
The implants are called corneal rings. They correct the shape of the cornea, the clear "window" that covers the front of the eye, altering the path that light takes as it passes through the eye and focusing it correctly on the retina at the back of the eye.
Nearsightedness is caused by corneal steepness, or increased length of the eye. As a result, the eye bends, or refracts, light incorrectly and focuses it before it reaches the retina. Corrective procedures for the problem - whether with lasers or implants - are called refractive surgery.
"The advantages of the corneal ring procedure are that the rings are potentially removable, so the procedure can be reversed, and also that the center part of the cornea is not directly affected by the surgery," says Alan Sugar, M.D., a corneal surgeon and associate chair of ophthalmology at the U-M, and one of the first surgeons trained to implant the rings.
Another advantage, he adds, is that the rings seem to correct sight better than laser procedures do, giving three out of four patients 20/20 vision and allowing half to see better than 20/20.
Still, he cautions, "There's no single procedure that's best for every patient, so we at the U-M offer a range of procedures for a range of individual patient needs."
Both the corneal rings and laser procedures underwent extensive testing before gaining approval from the Food and Drug Administration and becoming widely available. The first corneal ring implant to be approved is Intacs, made by Keravision. "The first patients treated were operated on in 1991," says Sugar, "and the long-term follow-up seems to be very good."
Still, some don't want to submit to a laser procedure that can't be reversed if new technology becomes available in coming years or if something goes slightly wrong - such as the haze, glare or nighttime "halo effect" reported by a minority of laser-treated patients. Studies of corneal rings showed they can be adjusted or removed without adverse affects.
On the other hand, the rings can only help those patients whose nearsightedness falls within minus one to minus three diopters, or optical measurement units.
Laser procedures like photorefractive keratectomy (PRK) or laser assisted in-situ keratomileusis (LASIK) have been approved for a wider range of vision problems. Those who are more severely nearsighted, farsighted or have an astigmatism caused by irregularly curved corneas, may have to wait several years before corneal rings are available to them.
For those who can consider corneal implants now, Sugar says, the operation is a relatively simple one performed on an outpatient basis. "It does require some technical skill, and it requires anesthesia in the form of eye drops. It takes about 15 minutes for each eye," he explains. The cost is comparable to laser surgery, about $2,000 per eye, though most insurance plans do not cover the expense. Recovery is rapid -- patients are usually back to work the next day.
So, Sugar says, patients who might be interested in the implants should consult with their eye doctors before deciding which optical option to choose.
Facts about nearsightedness and refractive surgery:
· An estimated 68 million Americans are nearsighted, about 20 million with a mild form.
· No procedure is 100 percent predictable, so some patients may sometimes need glasses.
· Studies show that 97 percent of corneal ring patients achieved 20/40 vision or better, 74 percent achieved 20/20 vision or better, while about 53 percent had 20/16 vision or better.
· Corneal rings are made of the same material used for years in some intraocular lenses to treat cataracts. - By Kara Gavin
Related websites:
UMHS Health Topics A to Z: Eye Care
U-M Kellogg Eye Center
American Academy of Ophthalmology: Refractive Errors and Surgery
[Contact: Kara Gavin, Andi McDonnell]
10-Jan-2000
unisci.com |
