title: [Predictability of the corneal flap creation with the femtosecond laser in LASIK].
abstract: OBJECTIVE
  To observe the predictability of corneal flap creation with the FEMTO LDV femtosecond laser and analyze preliminarily the factors correlating to the thickness and diameter of the flap .
  
  
  METHODS
  It was a study of serial cases. 260 eyes of 130 consecutive patients were treated with the FEMTO LDV. The eyes were assigned to two groups according to intended flap thickness, 110 µm (208 eyes) and 90 µm (52 eyes). Intended flap diameter varied from 8.5 to 9.5 mm. Difference analysis of flap diameter and intended diameter as well as flap thickness and intended thickness were made. The data was analyzed with SPSS to sum up a multiple stepwise regression formula that could express their quantitative relationship.
  
  
  RESULTS
  The 90 µm flap group had a average flap thickness of (95.12 ± 7.65) µm, while for the 110 µm group the average flap thickness was (104.81 ± 3.09) µm. The difference between right and left eyes was not statistically significant (t(110 µm) = -1.223, t(90 µm) = -1.343, P > 0.05). Corneal flap thickness was inversely correlated with flap diameter (r(110 µm) = -0.143, r(90 µm) = -0.315, P < 0.05), but was not related to preoperative patient age, corneal thickness, keratometric value K or intraocular pressure (r(110 µm) = -0.160, 0.054, -0.011, -0.363; r(90 µm) = 0.024, 0.074, -0.212, -0.434, all P > 0.05). Corneal flap diameter was positively correlated with preoperative corneal keratometric value K and thickness (P < 0.001, P < 0.05). Multiple stepwise regression analysis showed flap diameter was an influencing factor for flap thickness. Preoperative corneal keratometric value K and thickness were influencing factors for flap diameter.
  
  
  CONCLUSIONS
  The LASIK flap creation with the FEMTO LDV laser has relatively good predictability. Flap diameter is an influencing factor for flap thickness.
authors.affiliation: Department of Ophthalmology, Henan Armed Police Force General Hospital, Zhengzhou 450052, China.
authors.forename: Zhi-bin
authors.initials: ZB
authors.lastname: Mai
authors.forename: Su-bing
authors.initials: SB
authors.lastname: Liu
authors.forename: Xiao-li
authors.initials: XL
authors.lastname: Nie
authors.forename: Hong-xia
authors.initials: HX
authors.lastname: Sun
authors.forename: Bao-li
authors.initials: BL
authors.lastname: Xin
authors.forename: Xiu-xia
authors.initials: XX
authors.lastname: Tang
mesh_terms: D000293:Adolescent; D000328:Adult; D003315:Cornea / Q000033:anatomy & histology / Q000601:surgery*; D016039:Corneal Transplantation; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D008297:Male; D009216:Myopia / Q000601:surgery*; D013524:Surgical Flaps; D055815:Young Adult