In PRK Surgery, the thin corneal epithelial layer is removed. There are several approaches to doing this, including epi-LASIK and the use of an automated brush called the Amoils Brush. In my last blog, I looked at the differences between LASIK and PRK laser eye surgery. With LASIK, a flap is made, whereas with PRK, the thin surface coat — called the epithelial layer — is removed instead of making a LASIK flap. Because no LASIK flap is made, PRK can be used on corneas too thin for a LASIK flap and on corneas which are biomechanically too weak to support a LASIK flap.
There are various techniques for removing this microscopically thin epithelial layer covering the cornea. With older PRK technique, the epithelial layer was simply scraped off with a rough sponge. As the surgery evolved, however, other less traumatic approaches to removing the epithelial layer were evolved. A recent study compared recovery using two of these newer techniques. In particular, epi-LASIK was compared to use of a rotating automated brush to remove the corneal epithelial layer prior to applying the excimer laser to sculpt the cornea.
Epi-LASIK is a technique that uses a device called an “epi-keratome” to mechanically and abruptly slide the corneal epithelial layer off as one sheet. The goal is to make a very clean separation of the epithelial tissue from the underlying cornea. Originally, the technique was designed with the goal of replacing this epithelial sheet to cover the lasered cornea, much like a LASIK flap does in LASIK. Unfortunately, many researchers, including me, found that replacing this sheet actually caused more inflammation and slower healing than simply removing it. Removing — rather than replacing – the sheet is called “flap-off epi-LASIK” and is, in my opinion, a better way of performing epi-LASI. Flap off epi-LASIK technique was used in this military study.
The other approach in this study was the use of the Amoils automated rotating brush for epithelial removal. This brush looks similar to a miniature rotating car polishing brush. It is applied to the corneal tissue and “buffs” away the skin cells in the epithelial layer to remove them. Because it is soft, it will not harm the underlying cornea once it reaches it.
In this study, conducted through the U.S. military health care system, 120 eyes of 60 active-duty military patients with an average age of 27.3 years were studied. In one eye, epi-LASIK was performed (using the “flap-off” technique) whereas in the other eye, the epithelium was removed using the automated brush technique.
Results showed that the flap-off epi-LASIK group had significantly less discomfort in recovery than the automated brush removal eyes. The epi-LASIK eyes had smaller areas of epithelial layer removed than the brush group. The skin layer healed marginally quicker in the epi-LASIK group. Once the skin layer had healed, however, there was no statistically significant difference in vision between the two groups.
In the end, using “flap-off” epi-LASIK to remove the skin layer during PRK produced less pain and discomfort than using the automated brush, but the end results appear to have been the same.
See Also
Epi-LASIK Yields Less Pain Than Automated Brush Epithelial Removal in PRK
U.S. Military study comparing various techniques for removal of corneal epithelial layer in PRK laser eye surgery.
Taking the Pain out of PRK
An EyeWorld article looking a methods for reducing pain after PRK laser vision correction.
Classic Drawbacks of PRK Succumb to New Strategies
An article from the European Society of Cataract and Refractive Surgery reviewing different strategies to improve comfort and healing time after PRK laser eye surgery.
Epi-LASIK: Procedure of Choice
An expert opinion article about epi-LASIK in relation to other surface ablation PRK surgeries.
Epi-LASIK Eye Surgery: How It Works
All About Vision discussion of epi-LASIK.
LASIK vs. Other Treatments
A Doc Shop review of epi-LASIK compared to LASIK.