title: Repeatability of the modified Thorington card used to measure far heterophoria.
abstract: OBJECTIVE
  To determine the interexaminer and intraexaminer repeatability of the modified Thorington test (TH) for distance vision in young adults and to compare these results with those observed for the heterophoria tests most commonly used in clinical practice. Agreement among tests was also assessed.
  
  
  METHODS
  Distance heterophoria was quantified on two separate occasions by two examiners in 110 subjects aged 18 to 32 years (mean, 19.74 years; SD, 2.5 years) using four different tests: cover test (CT) Von Graefe, Maddox rod, and modified TH. The repeatability of the tests and agreement between them was estimated by the Bland and Altman method whereby the mean difference and the 95% limits of agreement were determined as the coefficient of repeatability (COR) and coefficient of agreement.
  
  
  RESULTS
  The Thorington test showed best interexaminer repeatability (COR = ±1.43Δ), followed closely by CT (COR = ±1.65Δ), whereas best intraexaminer repeatability was observed for CT (COR = ±1.28Δ) followed by TH (COR = ±1.51Δ). Among the different combinations of tests, TH and CT showed best agreement indicated by the lowest coefficient of agreement (±2.23Δ) and a low mean difference (-0.63Δ) between measurements.
  
  
  CONCLUSIONS
  Good interexaminer and intraexaminer repeatability was observed for both TH and CT, and agreement between the two tests was also good. Given the simple administration of the TH, we recommend its clinical use to quantify distance horizontal heterophoria.
authors.affiliation: *BSc †PhD Department of Optics II (Optometry and Vision), Faculty of Optics and Optometry, Complutense University of Madrid, Madrid, Spain (all authors).
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Cebrian
authors.forename: Beatriz
authors.initials: B
authors.lastname: Antona
authors.forename: Ana
authors.initials: A
authors.lastname: Barrio
authors.forename: Enrique
authors.initials: E
authors.lastname: Gonzalez
authors.forename: Angel
authors.initials: A
authors.lastname: Gutierrez
authors.forename: Isabel
authors.initials: I
authors.lastname: Sanchez
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D013285:Strabismus / Q000175:diagnosis*; D014787:Vision Tests / Q000295:instrumentation / Q000592:standards*; D055815:Young Adult