Femtosecond LASIK flaps: excellent, but superior?

s 2012 begins, femtosecond lasers have been used for more than a decade to create LASIK fl aps. 1 Starting with a single model, these lasers have gone through multiple iterations, and now multiple competing technologies are available in the market place worldwide. In the United States, recent surveys demonstrate continued increasing market share. Now more than half of all LASIK procedures are performed using femtosecond lasers, suggesting that there is some real or perceived superiority of these devices over mechanical microkeratomes. This increased utilization has occurred despite the increased cost of performing LASIK using a femtosecond laser; the absolute cost may vary from practice to practice, but invariably femtosecond LASIK is more costly for surgeons to perform. So, at this time when femtosecond lasers have surpassed microkeratomes in utilization and are making inroads into cataract procedures, again at increased expense but with the promise of superiority over current techniques, it seems reasonable to compare the perception to the data regarding femtosecond lasers and modern mechanical microkeratomes in the most relevant variables, including visual acuity and refractive outcomes , fl ap thickness parameters and reproducibility, and potential complications. VISUAL ACUITY AND REFRACTIVE OUTCOMES In this issue, Chen and colleagues 2 performed a meta-analysis comparing the IntraLase femtosecond laser (Abbott Medical Optics, Santa Ana, California) to a variety of mechanical microkeratomes, specifi cally focus-ing on uncorrected and corrected distance visual acu-ity, spherical equivalent and cylinder correction, and fl ap thickness. In short, the authors found no significant differences between technologies except for fl ap thickness predictability. These results mirror another meta-analysis performed by a separate group who utilized randomized controlled trials only. 3 These results and methodology will surely be thoroughly scrutinized ; however, the data appear to be a compelling report of equivalence between technologies. FLAP THICKNESS, VARIABILITY, AND ARCHITECTURE Chen and colleagues 2 did fi nd signifi cant differences in fl ap thickness predictability between the IntraLase and mechanical microkeratomes included in their analysis—a difference that has been echoed by numerous authors. The preponderance of evidence suggests that femtosecond lasers create thinner, more predictable fl aps than most mechanical microkeratome units. 4-7 However, fl ap thickness variability certainly exists with femtosecond lasers as well as microkera-tomes, 7 and at least some modern mechanical micro-keratomes appear equivalent to their femtosecond laser counterparts in creating thin, reproducible fl aps to their femtosecond laser counterparts. A recent study by my colleagues 8 …