PRK (Photorefractive Keratectomy) means removing (shaping) corneal tissue
by light (laser) in order to achieve the desired refractive correction.
Practically PRK is the first laser vision correction treatment offered
to spectacle/contact lens-dependent people. Newer patient-friendly laser
techniques such as LASIK and LASEK pushed PRK to third place in the
eyes of refractive surgeons.
What
are the advantages of PRK?
One of the advantages of the PRK method is that it is an easy surgical
procedure. Even a novice eye surgeon can accomplish a PRK operation
after watching a few videotapes. But precise programming of the Excimer
Laser for the desired vision requires years of experience, since every
doctor's surgical method and the environmental factors require construction
of special nomograms for specific prescriptions and age. Another advantage
of PRK is its being a quick, painless and bloodless laser procedure.
PRK consumes lesser corneal tissue than LASIK. PRK or LASEK become the
obvious choice when corneal thickness is critical (=thin cornea).
What are the disadvantages of PRK?
One disadvantage of PRK is its slow and painful recovery period. Even
though many special techniques, such as bandage contact lenses have
been developed for relieving the after-operation pain, still some discomfort
should be expected for 2 to 5 days. Also the vision is blurry during
this period. This may delay PRK patients' resuming "the normal
life" which is the very next day for LASIK patients. Since PRK
is a technique that harms the epithelium of the cornea, a clear vision
should be expected after the total regeneration of the epithelium (2
to 15 days). Also achieving the final visual result may take up to six
months and the recovery modulating drops (such as steroids) should be
instilled during this time under the surveillance of regular doctor
visits. Two more unwanted effects of PRK should be mentioned. These
are especially valid for the treatment of high diopters and in case
of neglecting some preventive measures:
1. Persistent foggy vision: haze.
2. Regression: After having a normal vision for a while, a portion of
the old refractive error may come back.
When do we prefer PRK?
If
there is opacity (scarring) or a specific disease at the cornea
besides a refractive error, a dual-purpose laser therapy (PRK) may
be performed.
If
the anatomy of the eye does not allow placing a microkeratome safely
on the eye, then we may choose PRK instead of LASIK.
If
the cornea is too thin for LASIK then PRK or LASEK may be the procedure
of choice.
If
the patient wants to have an unnoticeable laser surgery even with
the microscope during an eye exam, then we consider performing PRK
or LASEK.
