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 Patients
with extremely thin corneas might be better off
with procedures other than IntraLASIK. A procedure
which does not create a flap would give us more
cornea to work with, to enable a more complete
correction and/or a bigger treatment zone diameter.
Advanced surface ablations are also known as LASEK
or PRK. These two techniques are extremely similar.
They involve removing the very surface layer of
the cornea, known as epithelium (usually about
50 microns thick), then lasering the exposed corneal
bed. This way, the laser is not vaporizing tissue
as deep in the cornea as with LASIK,
and the risk of ectasia (a de-stabilization of
the cornea caused by lasering too deeply into
the cornea) is lowered. With LASEK, a form of
alcohol is applied to the cornea, which loosens
the surface epithelium. After the laser part of
the procedure, the layer of alcohol-treated epithelial
cells is replaced over the treated area to act
as a bandage, and a contact lens is placed over
that. Much of the healing involves the regeneration
of new epithelium cells, over the course of a
week. With PRK, no alcohol is used, and the surface
epithelial cells are removed with a soft brush.
After the laser treatment, as with LASEK, a disposable
contact lens is placed on the eye, without replacing
the  damaged
epithelial cells. New epithelium regenerates naturally,
over two to three days. Both techniques are effective,
however Dr. Kawesch has found that the alcohol
used with LASEK causes significant inflammation
and delayed recovery of vision. In other words,
patients seem to see and recover more quickly
with PRK, without trying to salvage the surface
epithelium cells.
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