title: Comparison of corneal flap thickness using a FS200 femtosecond laser and a moria SBK microkeratome.
abstract: OBJECTIVE
  To evaluate differences in flap thickness resulting from use of an Alcon Wavelight FS200 femtosecond laser and a MORIA SBK microkeratome when making a 110-µm-thick corneal flap and to identify the potential factors that affect corneal flap thickness.
  
  
  METHODS
  A prospective case study was performed on 120 eyes of 60 patients who were divided into two groups for LASIK, each group consisting of 60 eyes (30 patients). The corneal flaps were created using an Alcon Wavelight FS200 femtosecond laser or a MORIA SBK microkeratome. The central corneal flap thickness was calculated by subtraction pachymetry. Age, central corneal thickness (CCT), spherical equivalent refraction, mean keratometry, and corneal diameter were recorded preoperatively for analysis.
  
  
  RESULTS
  Cutting of all flaps was easily performed without intraoperative complications. In the Alcon Wavelight FS200 femtosecond laser group, the mean right and left corneal flap thicknesses were 114.0±6.6 µm (range: 98-126) and 111.4±7.6 µm (range: 98-122), respectively. The difference (2.6±9.1 µm) in the corneal flap thickness between the right and left eyes was not significant (t=1.59, P=0.12). Stepwise regression analysis indicated that the resulting corneal flap thickness was unrelated to the patient's age, preoperative CCT, spherical equivalent refraction, mean keratometry, or corneal diameter. In the MORIA SBK microkeratome group, the mean right and left corneal flap thicknesses were 110.6±7.4 µm (range: 97-125 µm) and 108.2±6.1 µm (range: 78-123 µm), respectively. The difference in the corneal flap thickness between the right and left eyes (2.4±6.5µm) was not significant (t=2.039, P=0.0506). The corneal flap thickness was positively correlated with the preoperative CCT through stepwise regression analysis (r=0.297, P=0.021). The corneal flap thickness was not related to age, spherical equivalent refraction, mean keratometry, or corneal diameter. The corneal flap thickness was estimated using the following equation: Tflap=67.77+0.076 CCT (F=5.63, P=0.021).
  
  
  CONCLUSIONS
  Both the Alcon Wavelight FS200 femtosecond laser and the MORIA SBK microkeratome produced 110-µm-thick corneal flaps. The central corneal flap thickness was positively correlated with the preoperative CCT in MORIA SBK microkeratome surgery.
authors.affiliation: New Vision Eye Clinic, Shanghai 200011, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: New Vision Eye Clinic, Shanghai 200011, China.
authors.forename: Shi-Sheng
authors.initials: SS
authors.lastname: Zhang
authors.affiliation: New Vision Eye Clinic, Shanghai 200011, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Yu
authors.affiliation: New Vision Eye Clinic, Shanghai 200011, China.
authors.forename: Jiang-Xiu
authors.initials: JX
authors.lastname: Wu
authors.affiliation: New Vision Eye Clinic, Shanghai 200011, China ; Department of Ophthalmology, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200025, China.
authors.forename: Jing-Cai
authors.initials: JC
authors.lastname: Lian
keywords: corneal flap thickness; femtosecond laser; laser in situ keratomileusis; microkeratome