Validity of the convergence insufficiency symptom survey: a confirmatory study.
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.
Rouse
Michael
M
Southern California College of Optometry, Fullerton, California 92831, USA. mrouse@scco.edu
Borsting
Eric
E
Mitchell
G Lynn
GL
Cotter
Susan A
SA
Kulp
Marjean
M
Scheiman
Mitchell
M
Barnhardt
Carmen
C
Bade
Annette
A
Yamada
Tomohiko
T
Yamada
Tomohike
T
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