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Thin-flap femtosecond or microkeratome LASIK safe in eyes of Chinese patients
J Refract Surg. 2010;26(2):99-106.
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LASIK with thin flaps created by femtosecond laser or microkeratome proved safe, effective and predictable in a Chinese population of high myopes, according to a study.
"The knowledge we gained in this study will likely help the process of introduction and education of Chinese surgeons in the understanding and adopting of this new laser technology," the study authors said.
The nonrandomized clinical trial included 274 eyes of 148 Chinese patients with mean spherical equivalent refraction of –8.94 D. Patients chose to receive femtosecond or microkeratome flaps. The femtosecond flap group comprised 134 eyes of 76 patients with a mean age of 28.7 years. The microkeratome group included 140 eyes of 72 patients with a mean age of 29.1 years.
Flaps were created with the 15-kHz IntraLase femtosecond laser (Abbott Medical Optics) or the Moria M2 microkeratome. Ablation was performed with the Visx S4 IR excimer laser (AMO) without wavefront-guided correction. No intraoperative complications or flap complications were reported.
At 3-month follow-up, both flap groups had similar uncorrected visual acuity, refraction, percentage of patients whose postoperative UCVA was better than preoperative best corrected visual acuity, tear production and tear breakup time.
In addition, 60.4% of eyes in the femtosecond flap group had spherical equivalent refraction within 0.5 D of the target and 87.3% of eyes had spherical equivalent refraction within 1 D of the target. In the microkeratome group, 57.9% of eyes had spherical equivalent refraction within 0.5 D of the target and 82.9% of eyes had spherical equivalent refraction within 1 D of the target.
Both groups showed similar induction of higher-order aberrations, the authors said.
In the article, the authors find predictable outcomes with both the femtosecond laser and the microkeratome, which has been shown previously in several studies. However, previously reported differences in outcomes between the laser and the microkeratome were not seen in this current study. As time has progressed, the microkeratomes have improved in flap predictability and quality, improving overall outcomes. However, so too has the femtosecond laser platform improved with time. Uncorrected visual acuity in the femtosecond laser group vs. the microkeratome group for 20/20 at 3 months was 83% and 86%, which is similar to previously reported series. The previously reported differences between higher-order aberrations (except for increased spherical aberrations in the microkeratome group compared with the femtosecond laser group); tear break-up time; Schirmer tests; and refractive predictability were not seen with this study. The authors offer randomization, flap thickness, and follow-up as possible differences between previous studies and theirs. I would add to that the fact of comparing an older femtosecond laser platform to newer microkeratome technology also is a possible reason for the differences. Whatever the case, this is an excellent study and shows the safety and efficacy of LASIK at this level of refractive error.
– Karl G. Stonecipher, MD
Medical
Director, TLC-Greensboro, N.C., Surgical Director, Amsurg-Greensboro, N.C.
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