What is the difference between LASIK, LASEK And PRK?
In general, there are three main Laser Eye Surgery methods for treating patients with refractive errors. In the video below, expert laser eye surgeon Mr Glenn Carp explains the differences between LASIK, LASEK and PRK.
There is a layer on the surface of the eye called the epithelium, which is replaced by the eye every 7 to 14 days.
In PRK—a type of ‘surface’ treatment—the epithelium is removed so the laser eye surgeon is able to reshape the permanent layer underneath.
Following this a contact lens is applied as a bandage to allow the epithelium to re-grow underneath the contact lens and re-populate the surface of the eye.
In LASEK—another surface treatment similar to PRK—the epithelium is also removed, but rather than discard it, it is just pushed to one side.
The permanent layer underneath is then reshaped and the epithelium moved back. A contact lens is again applied to the surface to protect it while the new layer re-populates underneath.
In LASIK Laser Eye Surgery, a thin flap is made in the epithelium that penetrates down to just below the surface of the permanent layer. This allows the surgeon a little doorway for re-shaping the permanent layer.
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By returning the flap to its original position, it’s only the edges of the flap that need to heal. Thus, the recovery time of LASIK is only a fraction of that of LASEK and PRK.
A closer look at refractive surgery
Removal of stromal tissue from the cornea does not usually lead to regeneration of stromal tissue; unlike removal of epithelial tissue which does lead to its re-growth. Therefore, removal of stromal tissue can result in permanent re-shaping of the cornea, and thus a stable change its focusing power.
The world’s most popular Laser Eye Surgery treatment: LASIK
LASIK (laser in situ keratomileusis), used to correct short-sightedness (myopia), long-sightedness (hyperopia), and astigmatism, is a form of refractive surgery in which a laser eye surgeon uses a specialised, precise, and computer-controlled corneal flap-making instrument, called a microkeratome, to create a thin flap in the epithelium.
The surgeon raises the corneal flap and lays it back whilst still attached to the cornea. Then using a state-of-the-art Excimer laser, they remove a pre-determined amount of stromal tissue from the exposed bed of the cornea.
The amount of tissue the laser removes is based on the pre-operative determination of the power of your eye; these measurements are usually in agreement with recent prescriptions for your glasses and/or contact lenses.
The surgeon replaces the flap, and within minutes natural forces hold it down on the cornea.
Usually within a few hours, the surface epithelium of the cornea begins to grow over the cut edge of the corneal flap and seal it into position.
Where it all began: PRK surgery
PRK (Photo-Refractive Keratectomy), is the original laser vision procedure which surgeons have successfully used to treat hundreds of thousands of patients since the 1980′s.
PRK was the first Laser Eye Surgery treatment to use the Excimer laser, an ultra-precise alternative to traditional scalpel-based refractive surgery procedures such as Radial Keratotomy (RK), which surgeons rarely perform.
The Laser Eye Surgery hybrid: LASEK
LASEK surgery is a hybrid of PRK and LASIK.
The goal of LASEK is the preservation of the corneal epithelium. Rather than creating a corneal flap with a microkeratome (as in LASIK), or scraping and removing the patient’s epithelium (as in PRK), LASEK treats the epithelium with alcohol to loosen and separate it from the layer underneath so the surgeon can then roll it back.
The laser does it work by removing the underlying stromal tissue, ready for the the surgeon rolls the epithelial cells back to their original place.
This method used in LASEK offers many advantages over traditional PRK, including reducing postoperative haze, speeding up visual recovery, and decreasing postoperative pain. Thus placing LASEK somewhere in the middle ground between PRK and LASIK surgery.
Generally, PRK and LASEK should only be used when it’s not possible to use LASIK. Whilst PRK and LASEK produce good results in the correction of a full range of prescriptions, including myopia, hyperopia, presbyopia and astigmatism, the advantages of LASIK make it an all-round more effective procedure.
That being said, in an expert’s hands, visual outcomes between LASIK, PRK and LASEK are the same.Go back