title: Ocular residual astigmatism: effects of demographic and ocular parameters in myopic laser in situ keratomileusis.
abstract: OBJECTIVE
  To analyze the influence of demographic and ocular factors on ocular residual astigmatism (ORA) in myopic laser in situ keratomileusis (LASIK).
  
  
  METHODS
  University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
  
  
  METHODS
  Retrospective cross-sectional data analysis.
  
  
  METHODS
  Eyes of consecutive myopic patients scheduled for LASIK were studied to evaluate the influence on preexisting ORA of age, sex, ocular dominance, subjective cylinder and topographic astigmatism, subjective sphere, and mesopic pupil size. The ORA was determined using Alpins vector analysis. Two subgroups, defined by the ratio of ORA to preoperative refractive cylinder (R), were formed: ORA:R ≥ 1.0 and ORA:R <1.0).
  
  
  RESULTS
  The study comprised 2991 eyes (2991 patients). The mean ORA was 0.75 diopter (D) ± 0.39 (SD) (range 0.00 to 2.00 D); 1372 (46%) eyes had ORA of 1.00 D or more. Ordinary least square estimations and odds ratios showed that subjective sphere, male sex, and dominant eye were negative predictors of the degree of preoperative ORA, while increasing age and larger mesopic pupils did not indicate ORA orientation. With-the-rule astigmatism meridian was more likely in eyes with low ORA, while oblique and against-the-rule meridians were related to high ORA.
  
  
  CONCLUSIONS
  The preoperative assessment of refractive surgery candidates should consider the interaction between topographic, refractive, and ORA because corneal refractive surgery is more successful in eyes in which the cylinder mainly originates from the anterior cornea. The current data can help identify patients at high risk for having a significant difference between subjective cylinder and topographic astigmatism.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors: From the Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Electronic address: a.frings@uke.de.
authors: Andreas
authors: A
authors: Frings
authors: From the Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors: Toam
authors: T
authors: Katz
authors: From the Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors: Johannes
authors: J
authors: Steinberg
authors: From the Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors: Vasyl
authors: V
authors: Druchkiv
authors: From the Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors: Gisbert
authors: G
authors: Richard
authors: From the Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors: Stephan J
authors: SJ
authors: Linke
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001251:Astigmatism / Q000175:diagnosis / Q000503:physiopathology*; D003315:Cornea / Q000503:physiopathology*; D019781:Corneal Topography; D003430:Cross-Sectional Studies; D003710:Demography; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D016017:Odds Ratio; D057234:Preoperative Period; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult