title: Cyclotorsion Measured in a Patient Population Using Three Different Methods: A Comparative Study.
abstract: OBJECTIVE
  To establish if cyclotorsion measurements obtained in a patient population using different methods of testing give equivalent results, and if the results from each test are repeatable over time.
  
  
  METHODS
  Twenty referrals, from the orthoptic waiting list at Sahlgrenska University Hospital, Mölndal, Sweden, with vertical deviation stated as the primary reason for referral, were examined. Subjective cyclotorsion measurements using three different methods were performed. The methods included two standard tests: a synoptophore, with slides A17a/18a, the single Maddox rod test (SMR), and a new test method: the KMScreen method. Measurements were repeated 3 times for fixing either eye, and on two separate test occasions, for repeatability within each of the methods.
  
  
  RESULTS
  During the first test measurements, 11 (55%) showed excyclotorsion measured with the synoptophore method, 18 (90%) with the SMR test, and 15 (75%) with the KMScreen method. During the second set of measurements, 11 (55%) showed excyclotorsion with the synoptophore method, 17 (85%) with the SMR test, and 10 (50%) with the KMScreen test. Median perceived torsional measurements at the first visit for the synoptophore, SMR, and KMScreen tests were -1°, -5°, and -1°, respectively. There were significant differences between the synoptophore and SMR (P=0.025), and the SMR and KMScreen (P=0.025), but not between the synoptophore and KMScreen (P=0.90) methods on measuring the affected eye. All three tests showed repeatable values. The 95% limits of agreement (LoAs) between visits, defined as mean torsional difference ± 1.96 SD of difference, for the synoptophore, SMR, and KMScreen methods were -0.5° ± 4.5°, -0.3° ± 5°, and -0.7° ± 3.5°, respectively. P values for differences between visits were P=0.45, P=0.75, and P=0.90, respectively, using an exact permutation test.
  
  
  CONCLUSIONS
  In this small study group, the three different methods used for testing cyclotorsion showed significantly different results. However, all methods showed significant repeatability (test-retest reliability) over time. This finding is of clinical importance when investigating cyclotorsion in patients. Clinicians need to be aware of the differences between methods when monitoring recovery or changes in patients, and in particular when planning surgical correction for cyclotorsion.
authors.affiliation: a Department of Ophthalmology , Sahlgrenska University Hospital , Mölndal , Sweden.
authors.forename: Sara
authors.initials: S
authors.lastname: Flodin
authors.affiliation: a Department of Ophthalmology , Sahlgrenska University Hospital , Mölndal , Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Karlsson
authors.affiliation: a Department of Ophthalmology , Sahlgrenska University Hospital , Mölndal , Sweden.|b Department of Ophthalmology, Institute of Neuroscience and Physiology/Ophthalmology , Sahlgrenska Academy at the University of Gothenburg , Gothenburg , Sweden.
authors.forename: Marita
authors.initials: M
authors.lastname: Andersson Grönlund
mesh_terms: D000328:Adult; D000368:Aged; D003941:Diagnostic Techniques, Ophthalmological; D004172:Diplopia / Q000175:diagnosis / Q000503:physiopathology; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015835:Ocular Motility Disorders / Q000175:diagnosis* / Q000503:physiopathology; D009801:Oculomotor Muscles / Q000503:physiopathology; D009988:Orthoptics; D015203:Reproducibility of Results; D013285:Strabismus / Q000175:diagnosis / Q000503:physiopathology
keywords: Cyclotorsion; KMScreen; repeatability; single Maddox rod; synoptophore