A femtosecond laser is a class of lasers known as ultrashort lasers. They have the property that when the laser spot is shot into the cornea, it gets very tightly focused, and a small amount of corneal tissue (around 1 micron) gets converted into a gas bubble. Since these lasers fire at a very high frequency (in case of the lasers at New Vision, 500 Kilo Hertz), millions of shots can be laid down in a precise plane, wherein much of the tissue in a 1 micron thick layer gets converted into gas bubbles. Shots can even be stacked, one on top of the other, which allows the creation of a side cut incision. Thus, instead of using a high speed oscillating blade, as in a microkeratome, the laser is used to create the corneal flap.

Such a laser has many advantages over a microkeratome. Some flap complications, like irregular flaps, free flaps or buttonholes, simply don’t occur with a femtosecond laser. Even if there is a suction loss during the laser procedure, the laser procedure can be resumed immediately. So there is very little likelihood that a laser procedure would get postponed for any reason.

Second, the surgeon has a lot of flexibility while creating a flap with a femtosecond laser. The flap can be customized to a patient’s individual requirement, which is hard to do with a microkeratome. Further, studies show that fewer optical aberrations are induced in the eye by a femtosecond laser flap, compared with flaps made with a microkeratome.
Third, there is greater control over flap thickness. The VisuMax femtosecond laser that we use has a standard deviation in flap thickness of only 3 microns. This high level of accuracy means that the risk of ectasia is reduced to a large extent, because it is unlikely that a surgeon will get a surprise in the flap thickness.

Since the VisuMax laser suction is on the cornea, and it is quite a light suction, the patient does not experience a blackout during the procedure. Nor does the patient get any red spots. Thus the cosmetic irritant with microkeratome LASIK also does not exist.

Finally, there is less chance of a flap displacement with a femtosecond laser flap. Since the femtosecond laser is able to create a side cut incision, a vertical or acute angle incision can be created, which results in a “locked-in” flap, and a very strong bond between the flap and the remaining cornea. Thus, the chances that severely rubbing the eyes can cause a flap displacement are less than with a microkeratome.

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