Epi-LASIK more comfortable, restores vision faster than PRK
Though LASIK is currently the most popular laser vision correction surgery, there are times when an alternative procedure may be preferred. This is especially true if your corneas appear to be too thin for a safe LASIK procedure.
Alternative procedures include PRK and epi-LASIK. Both of these surgeries are called "surface ablation" procedures because only the thin outer protective layer of the cornea (the epithelium) is removed prior to the laser treatment.
By comparison, in LASIK, the corneal flap that's created prior to the laser treatment includes the epithelium and some of the underlying tissue of the cornea, called the stroma. With PRK and epi-LASIK, all of the stroma remains intact prior to the laser treatment, so the surgeon has more corneal thickness to work with.
How PRK and epi-LASIK differ
Though PRK and epi-LASIK are both considered surface ablation procedures, they differ in how the epithelium is removed.
In PRK, the epithelium usually removed manually after it has been softened with a dilute alcohol solution. (It also can be manually removed without application of alcohol, or it can be removed with a laser.) The removed epithelium is discarded, and an excimer laser is used to treat the underlying cornea. After the laser treatment, a bandage contact lens is applied to the eye for several days, until the epithelial layer of the corneal grows back.
In epi-LASIK, the epithelium is removed with a hand-held instrument called an epikeratome. The device is very similar to a microkeratome used in LASIK surgery, but the epikeratome removes only the thin epithelium from the underlying cornea. The surgeon may elect to keep the epithelium attached to the eye at one point (forming a "hinge," like on a LASIK flap), or discard it. After the laser treatment, a bandage contact lens is applied, like in PRK.
Surgeons prefer epi-LASIK over PRK
In a recent article in Ocular Surgery News, refractive surgeons Elizabeth Davis, MD, David Hardten, MD, and Richard Lindstrom, MD, all practicing at Minnesota Eye Consultants (Minneapolis), explain why they prefer epi-LASIK over the PRK procedure.
"Faster visual recovery is probably the biggest benefit," says Dr. Davis, noting that epi-LASIK patients at Minnesota Eye Consultants achieve good vision 1 to 2 days faster than PRK patients.
Dr. Lindstrom reports that 60% of eyes that had epi-LASIK at their practice attained 20/40 or better visual acuity (the legal requirement for driving in most states) the day after surgery. In comparison, only about 20% of PRK patients see this well 24 hours after surgery.
Three days after surgery, about 75% of epi-LASIK patients could see 20/40 or better, and at 1 week post-op, 90% were 20/40 or better.
Dr. Hardten agrees that though visual recovery after epi-LASIK still takes longer than after LASIK, it's faster than after PRK surgery. He also notes that new pain medications have significantly reduced post-operative discomfort in both epi-LASIK and PRK.
"We basically found minimal pain with either standard PRK or epi-LASIK because of our medical regimen," adds Dr. Lindstrom.
SOURCE: Epi-LASIK has faster recovery time, better pain management. Ocular Surgery News; Vol 25, No 17, Sept 15, 2007.
Last updated: February, 2010
