LASEK or LASIK-Which is it?
Robert M. Kershner, MD, FACS
Eye Laser Center, Suite 303, 1925 West Orange Grove Road, Tucson, AZ 85704-1152, Phone (520) 797-2020, e-mail: Kershner@EyeLaserCenter.com
"LASEK" by any other name is still PRK.
The future of the Microkeratome is
bright. When Excimer laser technology was first developed the concept was to
remove tissue from the cornea to reshape it. This removal of tissue resulted
in removing the epithelium (about 50 microns) and then Bowman's membrane.
Those of us who were avid refractive surgeons in those early days, were very
worried that this removal of surface tissue would result in unacceptable
scarring. Time proved us to be right. PRK was all there was to offer until
Gholam Peyman, MD adapted the microkeratome to the excimer procedure. Those
of us who were already performing ALK or automated lamellar keratoplasty
based upon the work of Luis Ruiz, MD and Jorge Barra quer, MD were
performing "mechanical LASIK". The only downfall to this procedure was the
inaccuracy in achieving the "second cut" to remove refractive tissue. The
excimer laser solved this problem for us, just as the adaptation of the
keratome solved the surface ablation problem for it.
The microkeratome was never designed for what it is asked to do today.
Because of this, most surgeons consider the keratome to be the single biggest
hurdle to acceptance of LASIK by surgeon and patient. Most consider the
microkeratome to be the most dangerous part of the procedure. This of course
doesn't have to be the case. With today's designs, such as the BD K3000, a
unit which is specifically designed for the LASIK procedure, the flap
creation can be safe, predictable and reproducible.
So why the motivation to return to LASEK or PRK? It is NOT because the
procedure is better. It is because mastering the microkeratome is still a
problem, perceived or otherwise, by most surgeons.
The reason LASEK cannot replace LASIK is because the procedure doesn't offer
the patient any real advantages, only the surgeon. I agree that for some
surgeons it may be easier and in their hands safer. However, any procedure
that removes the anterior condensation of corneal stroma (that area which
adheres the epithelium and prevents stromal scarring, known by the misnomer
Bowman's "membrane") cannot prevail as an acceptable refractive procedure.
LASEK has distinct disadvantages. It is longer to perform. It hurts. It is
unpredictable. It requires a bandage contact lens and re-epithelialzation
that takes at least a week. It requires long term steroids and antibiotic
coverage. Visual recovery is slow and if compared to LASIK, patients will
not accept the delay. It may still predispose to late epithelial erosions
or scarring, or the pseudonym "haze" as in PRK, because the procedure still
breaches Bowman's membrane. In a small number of cases, it may have an
advantage, such as in thin corneas where the ablation depth may preclude use
of the keratome. However, in these cases, the patient probably should not
have excimer laser treatment anyway and may be better off considering an
intraocular lens procedure. Therefore although LASEK may experience a
rediscovery, it offers nothing new or advantageous.
Only if a new procedure allows laser ablation to occur without breaching
Bowman's membrane and without cutting the cornea would it be acceptable as an
advance in this field. Presently, I believe surgeons and manufacturers would
be better positioned if they placed all their efforts to create a safer,
better, easier to learn and to adapt method of preparing the eye for laser
stromal ablation, than to abandon it for a trip back to the future.
Robert M. Kershner, MD, FACS