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INTRODUCTION
PRK
stands for Photo-Refractive Keratectomy. LASEK stands for laser
epithelial keratomileusis and is synonymous with PRK. Both PRK and LASEK are synonymous with Flapless LASIK, which is also referred to as Epi-LASIK. Therefore, there is absolutely no difference between PRK, LASEK, Flapless LASIK, and Epi-LASIK. These are just different names for the same procedure. PRK was the original procedure developed to perform laser vision
correction in 1995 when the Excimer laser was approved to treat
focusing errors (nearsightedness, farsightedness, and astigmatism)
of the eye. Unlike LASIK, which was formally introduced in 1997, PRK is performed on the surface or superficial portion
of the cornea to correct these focusing errors, while LASIK is
performed beneath the surface or on the deeper portion of the cornea. You see, the critical step in the laser vision correction procedure is gaining access to the deeper layer of the cornea called the stroma. The laser treatment is applied directly to this deeper layer (the stroma) in order to correct the vision. LASIK entails creating a flap in order to gain access to the stroma. PRK, LASEK, Flapless LASIK, and Epi-LASIK all entail removing the surface skin layer of the cornea (the epithelium) in order to gain access to the stroma.
THE
PRK PROCEDURE
PRK Step
1:
The cornea is composed of five layers. The most important layer with respect to the focusing of light is the deeper layer called the stroma, which is colored gray in the diagram on the left below and comprises most of the cornea. PRK entails removing the
protective skin that covers the surface of the cornea, the epithelium (the blue layer in the diagram on the left below) in order to gain access to the stroma. (See diagram on the right below)
PRK Step
2:
Once the stroma is exposed, the
Excimer laser is then used to remove the proper amount of corneal
tissue to correct for the individual focusing error (nearsightedness,
farsightedness, astigmatism) and reshape the cornea.
PRK Step
3:
At
the conclusion of the PRK treatment, a bandage soft contact lens
is placed over the cornea to allow for the surface to heal.
PRK
INDICATIONS
Because
of the slower visual recovery, PRK is generally performed in those
individuals who do not qualify for LASIK, because their corneas
are too thin. The visual recovery following PRK is slower,
because the vision remains blurry until the surface epithelium
of the cornea regrows, which takes about five days. Although
the vision returns much more rapidly following LASIK, the final
visual outcomes for LASIK and PRK are the same at one year.
Using
our individualized approach to laser vision correction at the
Flowers Vision Institute, we often deploy PRK to
optimize the visual outcomes for those patients, who do not qualify
for LASIK.
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