The excimer laser was first used in Canada for PRK
(photorefractive keratectomy) in 1990. The laser at the time was a
simplified form of those available today. The very first laser
could only correct nearsightedness (myopia). Shortly thereafter,
the laser was modified to allow treatment of astigmatism as well.
It was a few more years before farsightedness (hyperopia) was
treatable.
At the beginning of the procedure, drops are used to numb the
surface of the eye. An instrument is used to painlessly remove the
outermost layer of the cornea (called epithelium) in the area that
will receive laser treatment. The epithelium regenerates quickly,
taking usually three to five days to reseal the surface of the
eye.
Once the epithelium has been removed, the laser is used to reshape
the underlying surface. No discomfort is experienced during the
procedure, but an odor similar to burnt hair may be detected. Be
reassured that the excimer laser is considered a cold laser and
therefore nothing is burning. If the odor is smelled, it typically
lasts about a minute.
Some people will choose PRK over LASIK, others will be advised to
have PRK instead of LASIK for various reasons. Most people who
choose PRK themselves often do so because of occupational concerns
(some vocations recognize PRK but not LASIK). Others may want to
have the same procedure as a friend/relative had. If the examiner
suggests PRK over LASIK, it is often due to the corneal thickness
in comparison to the amount of treatment required (how high your
prescription is), or possibly certain types of corneal pathology.
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