title: Accuracy of corneal flap thickness achieved by two different age MK-2000 microkeratomes.
abstract: OBJECTIVE
  To investigate the accuracy of corneal flap thickness (FT) using two different age MK-2000 microkeratomes.
  
  
  METHODS
  The prospective cohort study enroled 260 patients with refractive error. Flaps were created using two microkeratomes A and B (new and aged, respectively) with 130-mum heads in two patient groups and two times the same blade in both treated eyes of each patient. The variations in FTs were compared between two groups and between both operated eyes of each patient. The correlations were analysed between FT and CCT or keratometric power.
  
  
  RESULTS
  In the A and B groups, the average FTs were 123.3+/-18.7 and 147.5+/-19.1 mum respectively. Difference in measurements between the actual FTs of first eye operations in the A group and intended 130 mum of FTs was not significant (P=0.462), but those of second operated eyes in the A group and both treated eyes in the B group were significant (P<0.001). Second cut achieved a thinner flap and increased the variability in FT, and an aged microkeratome achieved a thicker flap than a new microkeratome and than that claimed by the manufacturer. Positive correlations were observed between preoperative CCT and FT (P<0.05).
  
  
  CONCLUSIONS
  The first eye operation by a new MK-2000 microkeratome achieves the accuracy of the intended FT. FTs varied between first and second cuts of each patient and between two different age MK-2000 microkeratomes. LASIK surgeons should compare FT when using an aged MK-2000 microkeratome, and frequent and periodic comparison of FT achieved by all microkeratomes may be also recommended.
authors.affiliation: Department of Ophthalmology, Buddhist Tzu Chi General Hospital and Institute of Medicine and Medicine Science, College of Medicine, Tzu Chi University, Hualien, Taiwan.
authors.forename: S-Y
authors.initials: SY
authors.lastname: Hsu
authors.forename: Y-L
authors.initials: YL
authors.lastname: Liu
authors.forename: M-S
authors.initials: MS
authors.lastname: Chang
authors.forename: C-P
authors.initials: CP
authors.lastname: Lin
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000601:surgery; D015331:Cohort Studies; D003319:Corneal Stroma / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000295:instrumentation* / Q000592:standards; D008297:Male; D009216:Myopia / Q000601:surgery; D011446:Prospective Studies; D054140:Refractive Surgical Procedures; D013524:Surgical Flaps / Q000473:pathology*