All refractive laser treatments adjust the curvature of the cornea using laser beams.
Near-sighted or myopic corneas are made flatter, while far-sighted or hyperopic corneas are made steeper.
This adjustment ensures that light focuses sharply on the retina without the need for glasses or contact lenses.
There are various methods, and here we will discuss PRK, FemtoLASIK, and SMILE—some of the most common techniques worldwide, including at Gasthuisberg.
PRK (PhotoRefractive Keratectomy) is the oldest and simplest technique among refractive laser treatments.
In this technique, the superficial layer of the cornea, the epithelium, is first removed. The epithelium can be removed mechanically or with alcohol. When the epithelium is removed by the laser, it is called transPRK.
The exposed layer, the stroma, is then treated with the Excimer laser.
The recovery period is more challenging and takes longer for optimal vision, but after a few weeks or months, the results are as good as those from FemtoLASIK or SMILE.
LASEK (Laser-assisted SubEpithelial Keratectomy) and epiLASIK are very similar techniques aiming to reposition the epithelium.
The recovery and results for PRK, LASEK, and epiLASIK are quite similar.
PRK has a slightly narrower range compared to FemtoLASIK and SMILE but sometimes makes laser treatments possible for thinner corneas where FemtoLASIK and SMILE might not be feasible.
FemtoLASIK is the most traditional laser therapy, combining the use of two lasers.
First, the Femtosecond laser creates the corneal flap in a highly controlled manner.
Using infrared pulses at a speed of 1 quadrillionth of a second, the cornea is split to a desired depth with an accuracy of 5 microns.
Previously, the flap was cut with a mechanical microkeratome—a small device with a metal blade oscillating back and forth. Although this technique was also very reliable and precise, it has been replaced by the Femtosecond laser, which is even more accurate and efficient.
The flap thicknesses are very predictable, and the homogeneity of the cut surface is perfect. Thinner flaps can be made, allowing for the safe treatment of higher refractive errors.
However, the Femtosecond laser treatment is noticeably more expensive due to the high-tech equipment and costly disposable materials required for each procedure.
After lifting the flap, the cornea is reshaped with the second laser, the Excimer laser.
Since the flap is neatly repositioned and covers the underlying stroma, the recovery process is short and minimally painful. Vision recovers faster than with PRK and even faster than with SMILE.
SMILE (SMall Incision Lenticule Extraction) or ReLex SMILE is the least invasive and most innovative laser treatment, using only the Femtosecond laser.
The laser cuts a disc-shaped piece of tissue, a lenticule, from the cornea. The thickness and shape of this lenticule determine which refractive error is corrected.
A small opening is used to remove the lenticule by the surgeon.
Some studies suggest that SMILE may result in fewer dry eye issues compared to LASIK.
The corneal integrity is less disturbed since no flap is created.
With these advanced techniques, there are fewer complaints about reduced night vision, halos, contrast sensitivity loss, etc.
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