Custom PRK and
Advanced Surface Ablation at the San Diego LASIK Institute
Advanced surface ablation (ASA) is a group of procedures that
includes custom PRK with mitomycin C, LASEK, and Epi-LASIK. Patients who are candidates for this group of
procedures at the San Diego LASIK Institute include patients that are not candidates for LASIK and patients who
elect to have these procedures because they do not want to have a LASIK flap.
To understand the differences in these procedures it is
important to review corneal anatomy. The cornea has five layers. The important layers for laser vision
correction are the epithelial layer, Bowman's membrane, and the corneal stroma.
Layers of Cornea
- Epithelium (Dynamic Layer)
- Bowman's Membrane
- Stroma (Layer changed by the laser)
- Descemet's Membrane
The epithelium is the layer on top of the cornea. It is
composed of cells that are always actively piding, growing, and changing. This is like the epithelial layer of
our skin. It is a dynamic layer that always changes so if we lasered this layer only we will not make a
The difference in LASIK, custom PRK, and other ASA procedures
is how one gets to the deeper stroma layer. The stroma is a permanent layer.
Differences in Procedures
The LASIK surgeon creates a flap.
Either a microkeratome (blade) or a laser makes the flap. the surgeon opens the flap, the stroma is lasered and
the flap is placed back.
In custom PRK, the San Diego LASIK
Institute's surgeon uses a brush to remove the epithelial cells and let a new set grown in. The surgeon
essentially make a scratch on the eye, lasers, and then a new epithelial layer grows in and closes the
PRK has gone through two major
advances that have helped to reduce the incidence of corneal haze - lower spot sizes for the laser pulses and
the use of Mitomycin-C.
EPI-LASIK or LASEK:
In Epi-LASIK or LASEK, a surgeon
uses alcohol to loosen the epithelial layer. The surgeon then moves the epithelium to the side manually or with
a mechanical device. After the laser, the surgeon puts these alcohol weakened cells back on the cornea. The idea
with these two procedure is that there is less pain because the eye is covered up with cells as opposed to a
true "scratch" with PRK.
Unfortunately there is a high
failure rate in these alcohol weakened cells and they end up dying and then you would have a delayed PRK
Why the San Diego LASIK Institute Prefers Custom PRK with
- We do not have to use alcohol on the eye.
- Although the procedure is more painful, the healing is more
predictable in our opinion.
- There is no risk of nicking the eye with a mechanical device
- Our surgeon would rather a new layer of cells grow in than
put alcohol weakened cells back on the cornea.
*There are pros and cons to all procedures that any website
cannot completely cover. We would be happy to go in more detail with our patients at our consultation. All
viewpoints in this website are meant to be used as an education aide and are the sole viewpoints of the doctors
of the San Diego LASIK Institute.
© All content written and
copyrighted by the San Diego LASIK Institute
San Diego LASIK