title: Accuracy of the WASCA aberrometer refraction compared to manifest refraction in myopia.
abstract: OBJECTIVE
  To evaluate the accuracy of myopic refraction by a single measurement using the Wavefront Supported Custom Ablation (WASCA) aberrometer (Carl Zeiss Meditec AG, Jena, Germany).
  
  
  METHODS
  We retrospectively compared the refractive errors obtained by manifest refraction and wavefront refraction (WASCA) in 50 eyes of 25 consecutive myopic patients undergoing laser refractive surgery. The sphere ranged from -1.00 to -8.25 diopters (D) and cylinder from 0 to -3.75 D. WASCA measurements under cycloplegia were made and WASCA refractions calculated for a 6-mm analysis zone using the Seidel method within the WASCA. We used the manifest refraction as our best estimate of the true refractive error, therefore accuracy was defined as the difference between manifest refraction and that of the WASCA. Correlation coefficients and mean vector errors between manifest and WASCA refraction were calculated.
  
  
  RESULTS
  High correlation was shown between manifest and WASCA refractions, with correlation coefficients (R2) of 0.97, 0.85, and 0.79 for M, J180, and J45, respectively. Mean power vector error (standard deviation) was 0.22 D (0.39), +0.03 D (0.21), and +0.03 D (0.13) for M, J180, and J45, respectively. Total dioptric power vector error was 0.43 D with 74% eyes within 0.50 D.
  
  
  CONCLUSIONS
  When measuring normal myopic eyes, the concordance between manifest and WASCA refractions was found on average to be high; however, outlier measurements occurred.
authors.affiliation: London Vision Clinic, United Kingdom. dzr@londonvisionclinic.com
authors.forename: Dan Z
authors.initials: DZ
authors.lastname: Reinstein
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Archer
authors.forename: Darren
authors.initials: D
authors.lastname: Couch
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000175:diagnosis; D003315:Cornea / Q000473:pathology / Q000503:physiopathology; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D012029:Refraction, Ocular; D015203:Reproducibility of Results; D012189:Retrospective Studies