Femtosecond Laser to Correct Myopia

More than 90% of all laser vision correction procedures are done using the LASIK technique. LASIK is a two step procedure. First, a hinged flap at 100 to 180 micron corneal depth is created using a microkeratome. The flap is lifted to one side, and then in a second step, an excimer laser is used to ablate a precise lens from the remaining stromal bed. The flap is then replaced, where it sticks back in place, held eventually by an epithelial "glue" around the flap edges.

The microkeratome is a precise and delicate instrument. Most LASIK complications start from this instrument. These complications include free caps, buttonhole flaps, irregular flaps, incomplete flaps, and displaced flaps. Most of these problems arise not from surgeon error, but from difficulties with the microkeratome, and quality issues with the microkeratome blades. The mechanical nature of the microkeratome also creates the likelihood of wide variations in flap thickness, a factor which has been implicated in many cases of keratesia following LASIK.

In recent years, to obviate the difficulties of the microkeratome, the Femtosecond Laser has been introduced to create the LASIK flap. The Femtosecond laser uses extremely short, Femtosecond pulses of tightly focused light to create photodisruption within the cornea. Each pulse causes a tiny volume of tissue to turn into gas. When millions of such pulses are laid down in a precise manner, a flap can be created using a Femtosecond laser. In the last few years, the Femtosecond laser has dramatically improved the safety profile of the LASIK procedure. Not only are most flap complications eliminated, but the deep gutter around the flap allows the flap to "lock-in" to the remaining stroma. There is also relatively tight control over the thickness of the flap, with much less variation than with standard microkeratomes.

At New Vision Laser Centers (www.newvisionindia.com), we have been doing LASIK since 1995. We have recently introduced a femtosecond laser into our practice (www.newvisionfemtosecondlasikindia.com)

Because of these advantages, the Femtosecond laser has very quickly become part of the refractive surgery mainstream, a significant percentage of laser vision correction procedures are now done with the Femtosecond Laser. But the introduction of a Femtosecond laser into a LASIK practise is not without its own drawbacks. First, there is the problem of having two lasers, and the costs of acquiring, maintaining, and paying for the consumables and licenses of two lasers. Second, the space required increases sharply. Third, there is significant disruption in the workflow within the laser suite. At worst, the patient must be moved physically from one laser bed to another. At best, the patient must be moved from one laser to another using a pivoting patient bed. A physician using a Femtosecond laser must be prepared to spend a significant amount of extra time on operating each patient, relative to a microkeratome.