The objectives of the present study were to evaluate whether investigator bias influenced the Convergence Insufficiency Symptom Survey
) 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
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
enrolled in the CITT.
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).
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 ≥16 in distinguishing children
with symptomatic CI from those with NBV.