Epi-LASIK with new device produces promising results

January 1, 2005

Epi-LASIK is a promising new refractive procedure that potentially offers the visual recovery and minimal pain of LASIK without some of the well-known stromal flap complications.

Epi-LASIK is a promising new refractive procedure that potentially offers the visual recovery and minimal pain of LASIK without some of the well-known stromal flap complications.

Traditional LASIK, whether the flap is cut by a laser or a blade, involves certain biomechanical effects, possibly inducing aberrations. This can hinder the full benefits of sophisticated wavefront-driven ablations. Finally, creation of a LASIK flap can induce or increase the incidence of dry eye through the severing of corneal nerves. For all of the above reasons, we believe many surgeons would prefer surface ablation-if it could be done as painlessly as LASIK and with similar visual recovery.

The two most common surface ablation procedures-LASEK and PRK-have achieved only limited acceptance among surgeons and patients due to the recovery and pain issues. These procedures generate biochemical healing risks that include apoptosis, scarring, and irregular collagen formation. Furthermore, LASEK involves the administration of alcohol, which causes devitalization of corneal epithelial cells.

Unlike LASEK, in an Epi-LASIK procedure, there is no toxicity from chemicals such as alcohol. Although some of the epithelial cells do die during Epi-LASIK, it appears that more than 80% remain viable. After the epithelial flap is repositioned, these cells are distributed across the entire corneal surface, creating a very regular surface and a better physiological environment for cell regrowth. By contrast, after LASEK, the epithelial cells must regrow from the side. Epi-LASIK also avoids the haze and loss of best-corrected visual acuity (BCVA) sometimes associated with PRK.

Although we believe Epi-LASIK is an excellent alternative for all refractive patients, it is particularly worth considering in cases with thin corneas, high preoperative aberrations, and high K readings where a stromal flap might potentially produce worse results.

Unlike other devices designed for Epi-LASIK, the Epi-K has a disposable plastic head with an applanation front plate. Its pre-assembled dull metal blade is angled to cleave rather than cut the epithelium. Precision machining produces a uniformly and reproducibly blunt edge that separates the epithelium along the plane of least resistance, which appears to allow for a viable epithelial layer.

As it commences cleaving, the Epi-K makes a slow pass across the cornea, gently rubbing down to, but not cutting, Bowman's membrane. We have never cut stroma in any eye treated with the Epi-K.

The epithelial separator has dual suction ports located on the side, so that it can maintain lid position even in deep-set eyes with narrow fissures. There is also an on-top adjustable stop that avoids problems of short flaps in narrower eyes.

In addition to its clinical advantages, the Epi-K device is extremely easy to use and offers the surgeon the flexibility of working on one control unit to perform a variety of procedures, including LASIK and specialized lamellar procedures.

Intraoperative considerationsThe operation of the Epi-K feels like that of a standard LASIK keratome. After placing the suction ring on the eye and attaching the handpiece, the surgeon depresses the foot pedal to begin the Epi-K pass. The procedure is somewhat slower than LASIK but much faster than manual debridement of the epithelium.