Stanford tests
experimental treatment for farsightedness
BY MITCH LESLIE
An experimental method to
correct farsightedness is being tested at Stanford in the
nation's first clinical trial of the procedure.
The fast, painless
outpatient treatment uses radio-frequency energy to
reshape the front of the eye. For patients treated thus
far, the technique has provided immediate improvement in
vision, said Edward Manche, MD, assistant professor of
ophthamology and director of cornea and refractive
surgery. Vision continued to sharpen in the weeks after
the procedure as the eye settled into its new shape,
added Manche, who is national medical monitor of a
four-center FDA clinical trial of the effectiveness,
safety, and stability of the technique. The procedure has
been previously tested only in Italy and Mexico.
Since starting Stanford's
trial about six weeks ago, Manche has treated four
patients, all of whom now have at least 20/25 vision, he
said. Before the therapy, none had vision better than
20/40 -- the limit to drive legally without corrective
lenses, Manche said.
Manche presented
preliminary data on these patients April 11 at the annual
meeting of the American Society of Cataract and
Refractive Surgery, held in Seattle, Washington.
About 20 percent of the
U.S. population is farsighted, or hyperopic. Nearby
objects look blurry because light rays from those objects
focus at a point behind the retina of the eye.
Farsightedness results when the eyeball is too short or
when the magnifying power of the cornea, the clear
"window" at the front of the eye, is too low.
The procedure, known as
hyperopic radiofrequency thermokeratoplasty, works by
heating and shrinking the cornea with radio-frequency
energy. After numbing the eye with anesthetic drops,
Manche inserts a thin probe about the thickness of a pin
into the cornea and zaps the tissue with a burst of
radio-frequency. He repeats this step several times at
different points around the cornea, the exact number
depending on the severity of the patient's vision
problem. The procedure takes about two to five minutes
per eye.
Manche notes that speed is
just one of the advantages of this technique over laser
eye surgery, an alternative way to correct
farsightedness. In this treatment, known as LASIK, an
ophthamologist uses a laser to resculpt the cornea. Not
only is LASIK technically more challenging to learn, but
it requires much more expensive equipment, Manche said.
Margaret Duwe, an
administrative assistant in Stanford's biology
department, had the treatment performed on one eye about
a month ago. "Since the treatment, I am able to
drive and do most of my normal activities without
glasses," Duwe said. She is so impressed with the
results that she intends to have her other eye done as
soon as possible.
As for side effects, Duwe
said she experienced only tenderness of the eyeball for a
few days after receiving the treatment.
Side effects seem to be
limited to this eye irritation, which usually lasts for
two or three days following the procedure, Manche said.
In the international trials, no patients suffered any
vision reductions because of the procedure, Manche added.
One issue Manche and his
colleagues plan to follow closely is whether the vision
improvements persist. "The international trials
showed excellent stability, and we want to confirm that
the results remain stable over time," he said.
Within a year, Manche and
his colleagues expect to have enough data on the
procedure's effectiveness and safety to present to the
FDA, which must give its approval before the treatment
can enter general use. The other participants in the
trial are the Maloney Vision Institute in Los Angeles,
the New Jersey School of Medicine, and the Refractive
Surgery Center of the South in New Orleans.
Volunteers who are
farsighted and do not have astigmatism are still needed
for the study. Contact Sophia Talamantes at 498-7020 for
more information.
Refractec, Inc., the
manufacturer of the hyperopic radiofrequency
thermokeratoplasty machine, funded the trial. SR
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