8 Butterfly LASEK
Puwat Charukamnoetkanok, MD
Massachusetts Eye and Ear Infirmary, Schepens Eye Research Institute,
Harvard Medical School
Boston, MA
Suphi Taneri, MD
Zentrum für Refraktive Chirurgie Munster, Germany
In 1999, Vinciguerra developed a butterfly laser subepithelial keratomileusis (LASEK) to preserve the limbal connection of epithelial stem cells and limbal vascular connections
(1). He postulates that these connections enhance epithelial viability and are essential for re-establishing corneal epithelial adhesion and stratification (2). To date, he has treated more than 1,000 patients using this technique.
SURGICAL TECHNIQUE (FIG. 1)
Preoperative preparation: topical anesthetics, nonsteroidals, and/or antibiotics are applied before surgery. This is followed by preparation of the eyelids and positioning of the eye under the operating microscope. An eyelid drape is applied and a speculum is placed as described in Chapter 6.
Corneal marks, used in the Azar LASEK technique, may assist in replacement of the flap, but most surgeons do not use them when performing the Vinciguerra butterfly LASEK. A corneal alcohol well is used to apply the alcohol on the corneal epithelium (Fig. 2). There is no need to create a trephine mark to maximize the continuity between the epithelial flaps and the peripheral epithelium. Sharp-edged trephines can be used to apply to the alcohol but they should not be rotated, so as to avoid cutting the epithelium (Fig. 3).
The butterfly LASEK involves making a narrow paracentral epithelial incision from 8 to 11 o’clock. The 20% alcohol solution was applied to the corneal epithelial for 5 to 30 seconds (3). A specially designed spatula is used to separate epithelium from Bowman’s layer starting from the center and proceeding to the periphery on both sides (Fig. 4). A special retractor facilitates moving of the two epithelial flaps toward the limbus. Excimer laser photoablation proceeds after drying the stromal surface. The flaps are repositioned to cover the central cornea in an overlapping fashion (See Fig. 5.).
Vinciguerra et al. (2) compared conventional LASEK in one eye with the butterfly LASEK in the fellow eye of 35 patients. Preoperative mean spherical equivalent
LASEK, PRK, and excimer laser stromal surface ablation 96
refraction was −5.30±3.7 diopters (D). At 12 months postoperatively, mean spherical equivalent
Figure 1 Schematic illustration of the
Vinciguerra butterfly technique. (From
Taneri S, Zieske JD, Azar DT.
Evolution, Techniques, Clinical
Outcomes, and Pathophysiology of
LASEK: Review of the Literature.
Surv Ophthalmol. November-
December 2004 In press.)
Figure 2 Janach alcohol well (JANACH 2941).
Butterfly LASEK 97
Figure 3 Janach epithelial trephine (JANACH 2900).
Figure 4 Vinciguerra PRK/LASEK spatula (ASICO AE-2766).
refraction was within −1.0±0.4. There was no loss of best-corrected visual acuity (BCVA). At 12 months, 96.2% of the corneas were completely clear. The rest of the corneas had no more than trace of haze. Furthermore, 97% of the patients reportedly preferred butterfly LASEK to conventional LASEK because of increased comfort. The authors observed a more rapid return to epithelial transparency and visual recovery, which he attributed to a better flap viability in the butterfly LASEK.
CRUCIFORM LASEK
S. Percy Amoils developed the cruciform LASEK using a rotating microbrush to cut the cross (1). The surgeon created thin cruciate microgrooves using specially designed microbrush. The diluted alcohol solution is applied for 30 seconds. After removal of excess alcohol solution with sponge spear, the four flaps are then dissected back. The excimer laser is applied and the flaps are repositioned. Postoperatively, a bandage contact lens is placed for 3 days.
Advocates for this techniques reason that because all four flaps are left attached to the limbus, they are more viable because of better nutrition. Also, thinner epithelial incisions may result in faster healing.
LASEK, PRK, and excimer laser stromal surface ablation 98
Figure 5 (A) Star-shaped incision of epithelium as another variant of our technique. (B) Z-shaped incision of epithelium as another variant of our technique.
Butterfly LASEK 99
Figure 5 (CONT) (C) Ying-yang or S- shaped cut of epithelium as a variant of our technique. (D) Variant of Vinciguerra butterfly technique (without epithelial abrasion prior to alcohol application). (From Taneri S, Zieske JD, Azar DT. Evolution, Techniques, Clinical Outcomes, and Pathophysiology of LASEK: Review of the Literature. Surv Ophthalmol. November-December 2004 In press.)
LASEK, PRK, and excimer laser stromal surface ablation 100
REFERENCES
1.Samalonis LB. LASEK techniques. EyeWorld; 2002; 7:31–32.
2.Vinciguerra P, Camesasca FI. Butterfly laser epithelial keratomileusis for myopia. J Refract Surg; 2002; 18:S371–S373.
3.Chen CC, Chang JH, Lee JB, Javier J, Azar DT. Human corneal epithelial cell viability and morphology after dilute alcohol exposure. Invest Ophthalmol Vis Sci; 2002; 43:2593–2602.