The results of this study indicate that the CISS is a valid and reliable instrument for use as a primary outcome measure for 9- to18-year-old children enrolling in the CITT. Children with CI scored significantly higher than the NBV group on the CISS, suggesting that the survey is valid. In addition, an ICC of approximately 0.8 indicates that the CISS has good reliability.
The results of this study are similar to those found by Borsting and colleagues. 13,14 Both studies found that children with CI had significantly higher symptom scores than children with NBV. The total symptom score in this study is higher than that found in both of our previous studies 13,14; this is primarily because of the increased number of questions (13 to 15) and the expanded response categories (3 or 4 to 5) in the modified CISS. Our results are also consistent with those of McKeon and colleagues, 26 who used the Vision Function Scale in patients with intermittent exotropia. The Vision Function Scale has many items that are similar to the revised CISS (e.g., How often do you lose your place?). The intermittent exotropia group was found to have a higher symptom score than the visually normal group.
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