LASIK and Surface Treatment

Note: "Surface Treatment" has variously been called PRK, LASEK, epi-LASIK, ASA and "flapless LASIK"

In LASIK (Laser ASsisted Intra-stromal Keratomileusis), a precision instrument called a microkeratome is used to create a flap of corneal tissue a few thousandths of an inch thick. The flap is opened like the cover of a book, and the laser sculpts the desired optical correction into the collagen under the flap. When this is complete, the flap is closed, and seals almost immediately.

In Surface Treatment, the cells covering the outer corneal surface (called the epithelium) are removed, and the laser is employed to sculpt the front layers of collagen. The cells heal over the treated area in about 2-3 days. A 'band-aid' soft contact lens is placed to afford comfort during this time. After surface treatment, visual recovery to optimum levels usually takes several days to a few weeks. Eyedrops are necessary to help guide the healing process, and these usually need to be continued for several weeks after treatment.

There are various terms for surface treatment that have been employed since the inception of laser vision correction. The first procedure to be performed was called PRK (Photo-Refractive Keratectomy). In PRK, the surface lining cells are polished and removed, then laser treatment is rendered, and then the surface cells grow back. A newer term for this procedure is ASA (for "Advanced Surface Ablation")

LASEK - Epithelium lifted, then replaced ©2002 Robert Meyers Studio

To further confuse the consumer, some centers that strictly perform surface treatment market their services as a form of "flapless LASIK".  This is simply misleading.

All of these techniques use the excimer laser to perform the optical sculpting in exactly the same fashion.

Performing the laser sculpting under a flap, as in LASIK, eliminates the removal of the epithelial cells (as for surface treatment), and thereby dramatically reduces any 'scratchy' foreign body sensation, discomfort or pain after surgery. Also, visual recovery is typically faster with LASIK than with surface treatment - virtually immediate in some cases - as the optical integrity of the cornea is preserved. The benefits of LASIK include faster visual recovery, faster healing, less risk of haze or scarring, and less potential discomfort than with surface treatment.

Another perceived advantage of LASIK arises if enhancement or subsequent laser treatment is ever contemplated. After LASIK, re-treatment can usually be rendered simply by lifting the original flap. This is considered easier and more comfortable even than initial LASIK by the majority of patients who have enhancement. After PRK or LASEK, if retreatment is planned, the epithelium must again be removed as in the initial procedure; with the same healing and recovery considerations. In patients with myopia up to moderate ranges, both PRK and LASIK have shown comparably excellent visual results.

PRK may be recommended in situations where corneal thickness is not adequate to retain mechanical stability after taking into account the anticipated flap thickness and calculated depth of laser sculpting treatment. Experienced physicians do differ in their opinion on these issues. At LA Sight, all relevant factors are measured, and taken into consideration as a part of determining your candidacy for vision correction. To learn more about the testing we perform at the initial evaluation, see our page on the  Vision Consultation.