title: Prediction of flap response.
abstract: OBJECTIVE
  To find predictors of the induced biomechanical and optical effects of lamellar flap creation on the cornea.
  
  
  METHODS
  Optimed Eye and Laser Clinic, Pretoria, South Africa, and the Department of Ophthalmology and Biomedical Engineering Center, The Ohio State University, Columbus, Ohio, and Bausch & Lomb Vision Research Laboratory, Rochester, New York, USA.
  
  
  METHODS
  This prospective study monitored the refractive, wavefront aberration, and corneal topographic changes in 29 eyes of 15 patients for 3 months after the creation of a corneal lamellar flap. The main outcome measures for statistical analysis were refraction, total corneal thickness, residual corneal bed thickness, horizontal white-to-white corneal diameter, horizontal flap diameter, topography data, and wavefront data.
  
  
  RESULTS
  Statistically significant changes were seen in the autorefraction mode. Wavefront data showed significant change in 4 Zernike modes-90/180-degree astigmatism, vertical coma, horizontal coma, and spherical aberration. The topography data indicated the corneal biomechanical response was significantly predicted by stromal bed thickness in the early follow-up period and by total corneal pachymetry and flap diameter in a 2-parameter statistical model in the late follow-up period.
  
  
  CONCLUSIONS
  Uncomplicated lamellar flap creation is responsible for systematic changes in corneal topography and induction of higher-order optical aberrations. Predictors of this response include stromal bed thickness, flap diameter, and total corneal pachymetry.
authors.affiliation: Optimed Eye and Laser Clinic, Pretoria, South Africa. dr.potgieter@lasik.co.za
authors.forename: Frederik J
authors.initials: FJ
authors.lastname: Potgieter
authors.forename: Cynthia
authors.initials: C
authors.lastname: Roberts
authors.forename: Ian G
authors.initials: IG
authors.lastname: Cox
authors.forename: Ashraf M
authors.initials: AM
authors.lastname: Mahmoud
authors.forename: Edward E
authors.initials: EE
authors.lastname: Herderick
authors.forename: Marlize
authors.initials: M
authors.lastname: Roetz
authors.forename: Wouter
authors.initials: W
authors.lastname: Steenkamp
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D003315:Cornea / Q000503:physiopathology*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D013524:Surgical Flaps; D014792:Visual Acuity / Q000502:physiology