LASIK is an acronym which means the letters each stand for a word.  In this case it is Laser Assisted Stromal In-situ Keratomileusis.  This is definitely a mouthful, and when we were in the early 1990's trying to come up with a word describing this procedure, this seemed to make sense.  It was preceded by another acronym, ALK, which stood for Automated Lamellar Keratoplasty, and was the non-laser predecessor of the LASIK procedure.  We began doing ALK in the early 1990's and this was a procedure where a flap was made with a microkeratome, some tissue was cut using the same microkeratome with some special settings, and the flap was replaced.  It worked fairly well, but when lasers came along, it seemed obvious that the increased accuracy of the laser would make this a better procedure for vision correction.  Thus the LA (Laser Assisted) in LASIK.  Next we have Stromal which refers to the part of the cornea that is removed, the stroma or the structural part of the front surface of the eye.  In making a flap, we bypass the outer two layers (the epithelium and Bowman's membrane, and directly reshape the target tissue, the Stroma.  In-situ simply means we do it right there, as opposed to removing tissue and taking it into the shop for reshaping, and then replacing it.  Although this may sound absurd, it is exactly what was done in an even earlier procedure, called by another acronym, MKM.  Myopic Kerato Mileusis is where the outer cornea is removed, frozen on a special lathe (the shop) and then returned and sewn back onto the eye.   This procedure was first invented by Jose Barraquer about 40 or so years ago and you might be starting to see some similarity to all of these procedures and names. The Keratomileusis in LASIK is very similar to the keratomileusis done by Barraquer except he froze and lathed the tissue while today we use a "cold" laser to do the same job more accurately and we can do it directly on the eye without having to remove any tissue.  Thus LASIK has been 40 or so years in the making to get to where it is today.

So how has LASIK changed in the last 15 years since we first started doing it?  It is basically the same but there have been some significant improvements.  First, instead of using a modified keratome, which is an electric razor, we use a special kind of laser, the femtosecond laser that was first introduced as the Intralase, and later improved with the other version we have known as the VisuMax.  The trick is to cut a very thin piece of tissue from the front surface of the eye to expose the stroma which is reshaped with the second laser, the excimer laser.  The laser is definitely better than the razor and makes the procedure an all laser and software controlled process not dependent on mechanical moving parts.  It is like the jet engine is much more simple and reliable as compared to older propeller engines which were good but we can see that a majority of air travel is jet engine based.  Similarly, there is now over 50% of cases of LASIK being done with the all laser method, a major advance from when we first introduced the Intralase laser about 10 years ago as one of the first 3 sites in the USA and 4th in the world.  In fact, we did 90% of the first 1000 Intralase cases, which now number in the millions!

The other part of the procedure has advanced as well.  In 1995 Dr. Dishler introduced LASIK to Colorado for the first time.  We used our own laser, the Dishler Excimer LASER which was later granted approval by the FDA (in 1999) and was one of a very few medical devices developed by a private practice doctor and granted this honor.  It was state of the art at the time, and used a commercial laser engine source which was delivered through very unique optics and produced excellent clinical results for thousands of patients.  In fact, one laser still in use today is based on similar principles to the Dishler laser. 

We now employ two different excimer lasers, both offering excellent clinical results and both working on similar principles of using tiny laser pulses, applied very rapidly under the control of an active eye tracker to produce special shapes that give the best possible vision to our patients.  These are the Zeiss Mel 80 laser, and the Allegretto laser by Alcon/Wavelight.  They are designed to produce a custom correction that is optimized to give the best possible vision to patients.

The flap laser, the femtosecond laser is a cutting laser, and it makes tiny spots in the cornea by focusing through the surface, all at a precise depth that when considered as a collection of spots, separates the tissue at a precise depth, thus creating a flap.  This is similar to perforating paper which can then be easily torn, but to a much, much finer degree.  The excimer laser works differently.  Here tiny pulses of ultraviolet light strike the surface of the eye, and remove extremely tiny amounts of tissue with each pulse.  The best comparison is that they are gently sanding the surface to a new smooth shape.

When the flap is replaced, the edge, or seam heals very quickly, sometimes in less than a day, and vision is restored to a quality comparable to wearing contact lenses.  This gives the "wow" effect that LASIK is known for and has helped to make it so popular.  Because the change is in the Stroma, which is quickly recovered by the outer layers, the eye does not experience a reaction that would occur if the outer layers were directly treated, and thus has led to the extreme happiness that so many LASIK patients have throughout the world.