title: A comparison of near-dissociated heterophoria tests in free space.
abstract: BACKGROUND
  Many clinical techniques exist to quantify the magnitude of heterophoria in free space. In this article, we determine the agreement between the modified Thorington test and three different tests for dissociated heterophoria at near distance in free space.
  
  
  METHODS
  The modified Thorington, Maddox rod, von Graefe and alternate cover tests were performed on 49 university students at near distance in free space. The 95% limits of agreement between the modified Thorington and other tests were compared in pairs by using the Bland-Altman statistical test.
  
  
  RESULTS
  While the Maddox rod-modified Thorington pair showed narrow 95% limit range (2.5 to -3.34(Δ) ) between each other compared to the von Graefe-modified Thorington (4.2 to -3.15(Δ) ) and alternate cover test-modified Thorington pairs (4.52 to -2.77(Δ) ), none of the three tests showed good agreement with the modified Thorington test.
  
  
  CONCLUSIONS
  The modified Thorington test cannot be interchanged with the other three near tests for heterophoria in free space. The accuracy in the measurement and the different methods of dissociation may play a crucial role in comparisons of the different tests for heterophoria.
authors.affiliation: Department of Optometry, Manipal College of Allied Health Sciences, Manipal University, Karnataka, India. nijilsanker@gmail.com
authors.forename: Nijil
authors.initials: N
authors.lastname: Sanker
authors.forename: Avinash
authors.initials: A
authors.lastname: Prabhu
authors.forename: Avik
authors.initials: A
authors.lastname: Ray
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009801:Oculomotor Muscles / Q000502:physiology*; D009907:Optometry / Q000379:methods*; D012016:Reference Values; D013285:Strabismus / Q000175:diagnosis / Q000503:physiopathology; D014787:Vision Tests; D055815:Young Adult