title: A new subjective refraction method--the meridional polarized vernier optometer.
abstract: BACKGROUND
  The purpose of this study was to develop a more accurate and precise method for measuring subjective sphero-cylindrical refractive errors. It employed the principles of a vernier optometer and meridional refraction.
  
  
  METHODS
  A meridional polarized vernier optometer was used to measure the refraction of three subjects. Trial lenses were added to change the refractive error by known amounts and refractions were repeated to assess accuracy.
  
  
  RESULTS
  Refractions were within the range expected. The instrument had a slight bias (+0.04D) and 95 percent confidence interval of +/- 0.45D for measuring change in refractive error. Mean standard deviation for repeated measurements was 0.08D.
  
  
  CONCLUSIONS
  This new approach has the potential to measure subjective refractive errors more accurately than is possible with current methods.
authors.affiliation: Indiana University School of Optometry, Bloomington 47405, USA.
authors.forename: T O
authors.initials: TO
authors.lastname: Salmon
authors.forename: D G
authors.initials: DG
authors.lastname: Horner
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007909:Lenses; D008297:Male; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000175:diagnosis* / Q000503:physiopathology; D014787:Vision Tests / Q000379:methods*; D014792:Visual Acuity