[Examination of blades used in LASIK by scanning electron microscopy]

To evaluate and compare, by scanning electron microscopy (SEM), the sharpness of the edge of brand new surgical blades and consecutively used surgical blades in laser-assisted in situ keratomileusis (LASIK).

Twenty-five AccuGlide (Bausch & Lomb, USA) surgical blades were evaluated, divided into 3 groups: Group 1 (control), non-used surgical blades; Group 2, ten surgical blades used twice (simultaneous bilateral procedure); Group 3, ten surgical blades used four times (two consecutive simultaneous bilateral procedures). Each blade was analyzed by SEM at four random points, two central and two peripheral points, with magnification of 50x, 350x, and 1,000x.

Blade body irregularities and organic material were observed on all used surgical blades (Groups 2 and 3), but not on new surgical blades (Group 1). In addition, Group 3 revealed more irregularities in both central (p=0.0094) and peripheral points (p=0.0098) than Group 2, as well as organic material deposition (p=0.0204 and p=0.0909, respectively). Neither metallic material nor irregularities in the cutting edge of the blade were observed in any group.

No difference regarding the cutting edge was observed between new and blades reused up to four times, however irregularities and organic material were observed in all reused blades. Reusing blades for LASIK may produce structural changes and its clinical implications need to be evaluated due to the possible relation with interlamellar postoperative complications.