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PRK is an earlier technique of laser eye surgery that, along
with LASIK, makes up the two most common forms of refractive
surgeries today. The initials PRK refer to "photorefractive
keratectomy". "Photorefractive" has to do with the ability
of the eye to "refract" or focus light. Keratectomy refers
to a removal of a part of the cornea. PRK was the dominant
form of laser eye surgery until the development of the LASIK
technique.
The PRK process is very similar to LASIK. Both procedures
are performed on an outpatient basis. Both use the eximer
laser to reshape the curvature of the cornea in order to
correct for focusing problems. The shape of the cornea
largely determines how light enters the eye and is focused.
So, if the curvature of the cornea is too great or too
little in relationship to the length of the eye, light
cannot be properly focused on the retina.
As with LASIK surgery, a computer
measured map of the eye's surface is generated prior to
surgery to precisely adjust the settings of the eximer laser
to your individual prescription. Before the procedure is
performed, your eyes are also anesthetized with a few drops.
An eyelid holder keeps the eye open as the brief laser
surgery is completed. While PRK also uses a cool beam of
laser light, with PRK the laser is used to remove the outer
covering of the cornea (the epithelium) rather than folding
it back with a surgical device known as a microkeratome. The
PRK procedure uses the laser to remove the epithelium and
then reshape the underlying corneal material. There is no
incision of any kind with PRK. The outer layer of the cornea
which is removed by the laser is simply allowed to
regenerate over a period of about three days.
After PRK surgery, antibiotic and
anti-inflammatory eye drops are prescribed to help with
healing, reduce swelling and increase comfort. Since PRK
removes the outer corneal covering, a bandage contact lens
is used to protect the eye as it heals over the next two to
three days. During this time of healing, daily eye
examinations help to ensure that no infection develops. As a
final step in the healing process, PRK patients are given
anti-inflammatory drops for about two months following
surgery.