title: Reproducibility of flap thickness in sub-Bowman keratomileusis using a mechanical microkeratome.
abstract: OBJECTIVE
  To examine the predictability of flap thickness using a mechanical microkeratome (One Use-Plus) and identify factors related to variations in flap thickness in sub-Bowman keratomileusis (SBK).
  
  
  METHODS
  Tadawi Surgical Center, Taif, Saudi Arabia.
  
  
  METHODS
  Retrospective case series.
  
  
  METHODS
  Patients with a stable refraction for 1 year, corrected distance visual acuity (CDVA) of at least 20/20 in each eye, and minimum central corneal thickness of 480 μm in each eye had microkeratome-assisted SBK. Parameters included manifest refraction, uncorrected distance visual acuity (UDVA), CDVA, pachymetry, and higher-order aberrations (HOAs).
  
  
  RESULTS
  Seventy eyes (36 patients) were enrolled. The mean flap thickness was 88.74 μm ± 15.40 (SD) and the mean change in HOAs, 0.11 ± 0.30 μm(2). There was no correlation between flap thickness and age (r = -0.10), preoperative manifest refraction spherical equivalent (MRSE) (r = -0.08), preoperative cylinder (r = 0.13), postoperative CDVA (r = -0.17), or postoperative change in HOAs (r = -0.07). A strong positive correlation with preoperative pachymetry (r = 0.41) and a weak negative correlation with preoperative sphere (r = -0.21) were observed. There was no or a moderate negative correlation of pachymetry with age (r = -0.14), preoperative sphere (r = -0.36), cylinder (r = -0.04), or MRSE (r = -0.36).
  
  
  CONCLUSIONS
  The microkeratome was reliable with reasonable predictability for SBK flap creation. Extra caution in handling the flaps to avoid flap striae or tears is advised. Flap thickness correlated positively with preoperative pachymetry; however, the variation in flap thickness did not affect visual outcomes.
  
  
  BACKGROUND
  The author has no financial or proprietary interest in any material or method mentioned.
authors.affiliation: From Taif University, Taif, Saudi Arabia. Electronic address: tthomali@hotmail.com.
authors.forename: Talal Abdulrahman
authors.initials: TA
authors.lastname: Althomali
mesh_terms: D000293:Adolescent; D000328:Adult; D050541:Bowman Membrane; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000473:pathology*; D057108:Corneal Wavefront Aberration / Q000503:physiopathology; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000295:instrumentation; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D012029:Refraction, Ocular / Q000502:physiology; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013524:Surgical Flaps; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult