LASEK pioneer Massimo Camellin, MD, who is credited with creating the procedure as an alternative to LASIK, recently introduced a modification of LASEK to make it an even more attractive procedure.
LASEK is similar to LASIK, but the flap is much thinner and is created in a different way.
The LASEK flap consists only of the superficial layer of corneal cells (called the epithelium). A dilute alcohol solution is first applied to the eye for a brief period to loosen the epithelium from the underlying corneal tissue. The flap is then created by manually scraping the epithelial cells off to the side, leaving a hinge attached.
After the excimer laser treatment is completed, the flap of epithelial cells is replaced and covered with a bandage contact lens to promote healing.
The advantage of LASEK over LASIK is that LASEK often can be safely performed on corneas that may be too thin for LASIK. Also, because the epithelial cells grow back and adhere tightly to the underling corneal tissue after LASEK, there is no risk of delayed flap complications that can sometimes occur after LASIK.
While these advantages are also true of PRK, many surgeons prefer LASEK over PRK because the cornea may heal faster after LASEK, with less post-operative discomfort.
But one potential drawback of LASEK is that, in some cases, corneal haze may develop after surgery. It is believed that this haze, which may or may not affect vision, is due a toxic effect of the alcohol solution on corneal tissue, combined with the scraping motion required to create the epithelial flap.
Study of LASEK versus epi-LASIK
To improve LASEK outcomes and reduce the risk of corneal haze, Dr. Camellin first evaluated the surgical outcomes of LASEK and a similar laser eye surgery called epi-LASIK.
Epi-LASIK, like LASEK, creates an ultra-thin epithelial flap prior to laser treatment. But instead of the flap being created by scraping the alcohol-loosened epithelial cells to the side, in epi-LASIK the epithelial flap is created with a surgical instrument called an epikeratome. No alcohol solution is needed to first loosen the epithelium.
Dr. Camellin found that, though epi-LASIK avoided the toxic effect of alcohol on epithelial cells, the use of an epikeratome frequently would eliminate the hinge on the flap, causing a “free cap” — a complication where the epithelial flap is completely removed from the eye.
When this occurs, the epi-LASIK procedure essentially become the same procedure as PRK, in which the epithelium is intentionally removed and no flap is created. After PRK, the epithelium must grow back without the bandage effect provided by an overlying flap of epithelial tissue. Typically, this does not affect visual outcomes, but it can take a longer time for the eye to heal after PRK compared to LASEK or epi-LASIK.
To compare the results of LASEK versus epi-LASIK, Dr. Camellin evaluated the surgical outcomes of 67 patients. With each patient, LASEK was performed on one eye and epi-LASIK was performed on the other.
Study results showed:
- Flap quality was typically better in the epi-LASIK eyes, but frequently there were hinge problems and the formation of free caps with epi-LASIK.
- In the first two months after surgery, the LASEK eyes had less astigmatism.
- Though no clinically significant corneal haze developed in either group, a slight amount of haze was found three months after surgery in a minority of the LASEK eyes. This haze did not influence visual outcomes.
- Corneal topography and wavefront measurements indicated the epi-LASIK eyes had more irregularities in the central cornea in the first eight weeks after surgery, but this difference disappeared as more time passed.
- Some patients found the suction applied to the eye during the use of the epikeratome in the epi-LASIK procedure caused minor discomfort.
New epi-LASEK procedure combines best features of LASEK and epi-LASIK
To improve surgical outcomes, Dr. Camellin decided to develop a hybrid procedure that combines the best features of traditional LASEK and epi-LASIK. In this new procedure, which he calls “epi-LASEK,” Dr. Camellin soaks the cornea in a 20 percent alcohol solution for 20 seconds, and then uses an epikeratome to create the epithelial flap.
In a study of 45 patients, in which one eye was treated with traditional epi-LASIK and the other eye was treated with the new epi-LASEK procedure, results showed:
- The epi-LASEK eyes had significantly less astigmatism in the first eight weeks after surgery.
- The corneal surface was smoother in the epi-LASEK eyes.
- Flap quality was better in the epi-LASEK eyes, and no free caps occurred.
- Uncorrected visual acuity was slightly better in the first month in the epi-LASEK eyes. (Thereafter, the results were comparable).
- There was no significant difference in haze formation between the epi-LASEK and epi-LASIK eyes.
Because there was no significant corneal haze created by the epi-LASEK procedure, Dr. Camellin believes the corneal haze that sometimes occurs in traditional LASEK is likely due to the mechanical scraping of the eye that occurs in that procedure after the alcohol soak, rather than because of the alcohol solution itself.
Dr. Camellin concludes that the new epi-LASEK procedure is an improvement over traditional LASEK and epi-LASIK procedures and offers advantages over LASIK and PRK as well.
SOURCES:
- Epi-LASEK aims to minimize drawbacks of LASEK and epi-LASIK. Ocular Surgery News. February 10, 2009.
- Epi-LASIK versus epi-LASEK. Journal of Refractive Surgery. January 2008.