title: A pilot study examining density of suppression measurement in strabismus.
abstract: OBJECTIVE
  Establish whether the Sbisa bar, Bagolini filter (BF) bar, and neutral density filter (NDF) bar, used to measure density of suppression, are equivalent and possess test-retest reliability. Determine whether density of suppression is altered when measurement equipment/testing conditions are changed.
  
  
  METHODS
  Our pilot study had 10 subjects aged ≥18 years with childhood-onset strabismus, no ocular pathologies, and no binocular vision when manifest. Density of suppression upon repeated testing, with clinic lights on/off, and using a full/reduced intensity light source, was investigated. Results were analysed for test-retest reliability, equivalence, and changes with alteration of testing conditions.
  
  
  RESULTS
  Test-retest reliability issues were present for the BF bar (median 6 filter change from first to final test, p = 0.021) and NDF bar (median 5 filter change from first to final test, p = 0.002). Density of suppression was unaffected by environmental illumination or fixation light intensity variations. Density of suppression measurements were higher when measured with the NDF bar (e.g. NDF bar = 1.5, medium suppression, vs BF bar = 6.5, light suppression).
  
  
  CONCLUSIONS
  Test-retest reliability issues may be present for the two filter bars currently still under manufacture. Changes in testing conditions do not significantly affect test results, provided the same filter bar is used consistently for testing. Further studies in children with strabismus having active amblyopia treatment would be of benefit. Despite extensive use of these tests in the UK, this is to our knowledge the first study evaluating filter bar equivalence/reliability.
authors: Department of Vision Sciences, Glasgow Caledonian University , Glasgow , United Kingdom and.
authors: Marianne
authors: M
authors: Piano
authors: David
authors: D
authors: Newsham
mesh_terms: D000328:Adult; D000550:Amblyopia / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D005139:Eyeglasses; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D015203:Reproducibility of Results; D013285:Strabismus / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy; D014787:Vision Tests / Q000379:methods*; D015348:Vision, Binocular / Q000502:physiology
keywords: Amblyopia; binocular vision; strabismus; suppression