title: Validity of the convergence insufficiency symptom survey: a confirmatory study.
abstract: OBJECTIVE
  The objectives of the present study were to evaluate whether investigator bias influenced the Convergence Insufficiency Symptom Survey (CISS) scores of children with normal binocular vision (NBV) in our original validation study, reevaluate the usefulness of the cutoff score of 16, and reexamine the validity of the CISS.
  
  
  METHODS
  Six clinical sites participating in the Convergence Insufficiency Treatment Trial (CITT) enrolled 46 children 9 to <18 years with NBV. Examiners masked to the child's binocular vision status administered the CISS. The mean CISS score was compared with that from the children with NBV in the original, unmasked CISS study and also to that of the 221 symptomatic convergence insufficiency (CI) children enrolled in the CITT.
  
  
  RESULTS
  The mean (+/-standard deviation) CISS score for 46 subjects with NBV was 10.4 (+/-8.1). This was comparable with our prior unmasked NBV study (mean = 8.1 (+/-6.2); p = 0.11) but was significantly different from that of the CITT CI group (mean = 29.8 +/- 9.0; p < 0.001). Eighty-three percent of these NBV subjects scored <16 on the CISS, which is not statistically different from the 87.5% found in the original unmasked study (p = 0.49).
  
  
  CONCLUSIONS
  Examiner bias did not affect the CISS scores for subjects with NBV in our prior study. The CISS continues to be a valid instrument for quantifying symptoms in 9 to <18-year-old children. These results also confirm the validity of a cut-point of > or = 16 in distinguishing children with symptomatic CI from those with NBV.
authors.affiliation: Southern California College of Optometry, Fullerton, California 92831, USA. mrouse@scco.edu
authors.forename: Michael
authors.initials: M
authors.lastname: Rouse
authors.forename: Eric
authors.initials: E
authors.lastname: Borsting
authors.forename: G Lynn
authors.initials: GL
authors.lastname: Mitchell
authors.forename: Susan A
authors.initials: SA
authors.lastname: Cotter
authors.forename: Marjean
authors.initials: M
authors.lastname: Kulp
authors.forename: Mitchell
authors.initials: M
authors.lastname: Scheiman
authors.forename: Carmen
authors.initials: C
authors.lastname: Barnhardt
authors.forename: Annette
authors.initials: A
authors.lastname: Bade
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Yamada
authors.forename: Tomohike
authors.initials: T
authors.lastname: Yamada
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D015835:Ocular Motility Disorders / Q000503:physiopathology*; D012016:Reference Values; D012720:Severity of Illness Index; D016037:Single-Blind Method; D011795:Surveys and Questionnaires / Q000592:standards*; D015348:Vision, Binocular