Difference between revisions of "Photorefractive Keratectomy"
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== Additional Resources ==
== Additional Resources ==
== CME Resources ==
== CME Resources ==
Revision as of 08:57, February 6, 2011
PRK became less and less popular following the development of LASIK, a procedure that allowed patients to have their vision corrected without the need for extended recovery from surgery.
PRK vs. LASIK
LASIK, PRK, AND LASEK (a variant of PRK) are surgical techniques that use precise excimer laser energy to alter the refractive status of the eye. The difference in these procedures is where the excimer laser energy is applied.
LASIK consists of first making a corneal flap with a device called a microkeratome. A microkeratome is either a mechanical device that uses a blade or is laser-based. Here at Baylor Vision, we use the Intralase laser to create LASIK flaps. After the flap is created, the excimer laser removes small amounts of underlying tissue from the exposed cornea. Following the laser treatment, the flap is placed over the eye and carefully repositioned to complete the surgery.
LASEK is simply a variation of PRK in which the surface cells (epithelium) are soaked in a dilute solution of alcohol, pushed aside as a single sheet, and then pushed back over the surface of the corneal after the laser treatment is completed.
Therefore, all these operations involve use of the excimer laser to precisely remove the tissue. The primary difference is that the tissue removal is done under a flap with LASIK and on the surface of the cornea with PRK/LASEK.
Advantages of LASIK
There are several advantages to LASIK.
• Typically, there is little or no discomfort, both during and after the operation.
• Recovery of vision is rapid, and many people have useful vision within one day of surgery.
• If the outcome of the initial procedure does not meet expectations, then a retreatment can be performed. This is typically done at three months and consists of either lifting the flap that was made and applying an additional amount of laser treatment or doing the retreatment on the surface (like PRK).
Disadvantages of LASIK
• Because LASIK involves cutting a flap, it involves surgery that is deeper into the layers of the cornea. This could excessively weaken corneas of patients whose corneas are too thin.
• The creation of the flap also cuts corneal nerves and can increase dry eye symptoms in patients who are predisposed to this problem.
Advantages of PRK/LASEK
• PRK/LASEK avoids the use of the microkeratome or laser to make the LASIK flap. This leaves a greater portion of the cornea untouched by the surgery, which is important in patients who have thin corneas.
• In addition, there appears to be more rapid recovery of the function of the corneal nerves, which minimizes the amount of dryness that can be present following the procedure.
• PRK/LASEK may also provide an extra margin of safety in patients whose corneas have an unusual shape; this advantage is again due to leaving more of the cornea untouched by the surgery.
• If eye trauma were to occur following refractive laser surgery, there is less risk of complications with PRK/LASEK than with LASIK. With LASIK, the flap, in very rare instances, can become elevated or partially dislodged if the eye is struck at just the right angle with just the right object. This problem is obviously avoided with PRK/LASEK--because there is no flap. In PRK/LASEK, the trauma may cause a surface abrasion, but without a flap the abrasion would be the same as in an eye that had not undergone any laser surgery.
Disadvantages of PRK/LASEK
• For the first couple of days following PRK/LASEK, there can be mild to moderate eye discomfort. It takes several days for visual recovery, with good vision sometimes requiring 7-10 days, or in rare cases even longer. Depending on the rate of recovery of vision, patients can usually drive and return to work within 3 to 6 days after PRK/LASEK surgery.
• As in LASIK, if the outcome of the original procedure does not meet expectations, retreatment can be performed. This would essentially be the same process as the original surgery.
• PRK/LASEK patients are usually required to take cortisone drops for up to 4 months after surgery; the purpose of these drops is to minimize the risk of the development of haze in the cornea. A mild amount of haze is common, and this is not discernable by the patient. The purpose of the drops is to help prevent the development of any haze that might be noticeable to the patient.
Sachdeva R, Feldman B, Grewal S, Kreuger R.LASEK. E-Medicine from WebMD. June 21, 2007. Updated February 9, 2010. Available at:
2010 Focal Points Module: Innovations in Advanced Surface Laser Refractive Surgery.