title: Trial frame refraction versus autorefraction among new patients in a low-vision clinic.
abstract: OBJECTIVE
  To determine the relationship between refractive error as measured by autorefraction and that measured by trial frame refraction among a sample of adults with vision impairment seen in a university-based low-vision clinic and to determine if autorefraction might be a suitable replacement for trial frame refraction.
  
  
  METHODS
  A retrospective chart review of all new patients 19 years or older seen over an 18-month period was conducted and the following data collected: age, sex, primary ocular diagnosis, entering distance visual acuity, habitual correction, trial frame refraction, autorefraction, and distance visual acuity measured after trial frame refraction. Trial frame refraction and autorefraction were compared using paired t-tests, intraclass correlations, and Bland-Altman plots.
  
  
  RESULTS
  Final analyses included 440 patients for whom both trial frame refraction and autorefraction data were available for the better eye. Participants were mostly female (59%) with a mean age of 68 years (SD = 20). Age-related macular degeneration was the most common etiology for vision impairment (44%). Values for autorefraction and trial frame refraction were statistically different, but highly correlated for the spherical equivalent power (r = 0.92), the cylinder power (r = 0.80) and overall blurring strength (0.89). Although the values of the cross-cylinders J(0) and J(45) were similar, they were poorly correlated (0.08 and 0.15, respectively). The range of differences in spherical equivalent power was large (-8.6 to 4.9).
  
  
  CONCLUSIONS
  Autorefraction is highly correlated with trial frame refraction. Differences are sometimes substantial, making autorefraction an unsuitable substitute for trial frame refraction.
authors.affiliation: Department of Ophthalmology, School of Medicine, University of Alabama at Birmingham, Birmingham, AL 35233, USA. ddecarlo@uab.edu
authors.forename: Dawn K
authors.initials: DK
authors.lastname: DeCarlo
authors.forename: Gerald
authors.initials: G
authors.lastname: McGwin
authors.forename: Karen
authors.initials: K
authors.lastname: Searcey
authors.forename: Liyan
authors.initials: L
authors.lastname: Gao
authors.forename: Marsha
authors.initials: M
authors.lastname: Snow
authors.forename: John
authors.initials: J
authors.lastname: Waterbor
authors.forename: Cynthia
authors.initials: C
authors.lastname: Owsley
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D005139:Eyeglasses; D005260:Female; D006801:Humans; D008297:Male; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000175:diagnosis*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014787:Vision Tests / Q000295:instrumentation / Q000379:methods*; D015354:Vision, Low / Q000534:rehabilitation*; D014792:Visual Acuity / Q000502:physiology