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There
has been an interest in refractive surgery for almost 100 years.
Lans, a Dutch professor of Ophthalmology, laid out the basic principles
of radial keratotomy as early as 1898. In Japan,
in the 1930's, Sato did some pioneering work with corneal incisions.
He placed incisions in the endothelial surface of the cornea as
well as the epithelial surface, but this technique resulted in
late corneal decompensation for many of his patients.
It
took the observations of Dr. Fyodorov of Russia, in a case of
eye trauma in the 1970's, to bring about the practical application
of refractive surgery through radial keratotomy.
Fyodorov
was treating a boy whose glasses had broken, causing corneal
lacerations.
Following
recovery, this patient's refraction was significantly less myopic
than prior to the injury. This discovery prompted Fyodorov to
research past efforts in refractive surgery. He then worked out
a formula which made this procedure more predictable than
it had ever been before. In 1978, American ophthalmologists became
interested in these findings.
Dr.
Leo Bores was the first to bring the technology back to the
United States after visiting Fyodorov in the Soviet Union. Since
it was introduced, radial keratotomy has been performed on over
2 million patients in the United States alone.
Some
limitations of radial keratotomy prompted research into alternate
forms of refractive surgery.
Working
in the IBM research laboratories, Dr. Srinivasin saw the potential
of the Excimer laser in interacting with biological tissue. Dr.
Steven Trokel, an ophthalmologist, finally made that connection
to the cornea. This laser machine emits a non-thermal, cold beam,
that upon interaction with corneal tissue, breaks the carbon-carbon
bonds between molecules thus causing tissue ablation.
The
excimer laser has an international track record for safety and
effectiveness since 1987. Over two million procedures have been
done. It is projected that in the year 2000, over one million will
be treated in the U.S. alone.
The
first patient to have photorefractive keratectomy was treated
in Germany in 1988. As of November 1994, it is estimated that
over 1,000,000 PRK cases have been performed in 40 countries
around the world, with the number of cases rising exponentially -
especially in Europe and East Asia. With new refractive
technologies being actively developed, many feel confident in
the fact that refractive surgery is here to stay.
At
present, refractive surgery is most effective for myopia, astigmatism
and hyperopia.
LASIK is the most recent advance in laser vision correction.
LASIK is an acronym for Laser Assisted In-situ Keratomileusis. Compared to the
original laser PRK, the surface of the cornea remains largely intact
so that LASIK patients are more comfortable and see better more quickly.
LASIK has been performed internationally for approximately 10 years.
It was first performed in U.S. clinical trials in 1991. It is
important to note that the major components of the procedure have a
long history. Ophthalmologists have been reshaping the cornea for over
50 years, creating a protective layer of tissue for over 35 years, and
using the excimer laser since the 1980s.
In
1996, the FDA acted on the data submitted and approved the laser for
treatment of low myopia up to -6.00 diopters. In 1997, the FDA approved
the laser for treatment of astigmatism up to -4.00 diopters. There are
currently three major manufacturers of the excimer laser equipment:
Summit Technology, Visx and Nidek.
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