title: Distribution of corneal spherical aberration in a comprehensive ophthalmology practice and whether keratometry can predict aberration values.
abstract: OBJECTIVE
  To determine the spherical aberration of the cornea in the general population and whether keratometry readings are predictive of corneal spherical aberration values.
  
  
  METHODS
  Private comprehensive ophthalmology practice.
  
  
  METHODS
  Corneal spherical aberration and keratometry readings were measured in 696 normal eyes of patients presenting for ocular examination to a comprehensive ophthalmologist. The Easygraph (Oculus) was used to measure the corneal topography and keratometry readings in patients with healthy corneas. The analysis was performed using software in the Easygraph to determine the Zernike coefficients for each cornea. The keratometry and spherical aberration (Zernike coefficient Z(4)(0)) were then statistically analyzed.
  
  
  RESULTS
  The corneal spherical aberration, analyzed by the Kolmogorov-Smirnov test for normality, fit a normal Gaussian distribution. The spherical aberration value was (+0.274 +/- 0.089) x 10(-3), measured at an optical zone of 6.0 mm. A very weak correlation was found between corneal spherical aberration and central keratometry readings of the cornea: Corneal spherical aberration = {0.017 x (mean keratometry) - 0.457} x 10(-3).
  
  
  CONCLUSIONS
  The corneal spherical aberration distribution was a normal Gaussian curve. However, the mean value was significantly different when the sex of the patient was considered. Corneal keratometry readings could not be reliably used to predict corneal spherical aberration.
authors.affiliation: Ontario Street Site of the Niagara Health System, St. Catharines, Ontario, Canada. george.beiko@sympatico.ca
authors.forename: George H H
authors.initials: GH
authors.lastname: Beiko
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Haigis
authors.forename: Andreas
authors.initials: A
authors.lastname: Steinmueller
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015350:Contrast Sensitivity; D003316:Corneal Diseases / Q000175:diagnosis*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016011:Normal Distribution; D009885:Ophthalmology; D011364:Professional Practice; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000175:diagnosis*