Gladys Mitchell


PURPOSE. The purpose of this pilot study was to evaluate the utility of the Convergence Insufficiency Treatment Trial Symptom Survey (CITT-SS) as the primary outcome in a clinical trial. As such, it was important to show that the instrument was repeatable and could distinguish between convergence insufficiency (CI) and normal binocular vision (BV) subjects.

METHOD. The symptom survey was administered twice to 41 children (ages 9-18) with CI. The average time between completion of the surveys was 12.5 days (SD=7.7). The same survey was administered to 27 children with normal BV. To assess repeatability, the intraclass correlation coefficient (ICC) and the 95% limits of agreement (LoA) were determined. The ability of the CITT-SS to discriminate CI and normal BV subjects was assessed by comparing the mean score between the two groups. In addition, the sensitivity and specificity of the survey at various cutpoints was examined.

RESULTS. The mean symptom survey score for CI subjects was 32.0 (SD=8.2) at time 1 and 32.8 (SD=8.2) at time 2. The ICC was 0.764 and the 95% LoA were-1.0 to 2.6. Both of these statistics indicate good repeatability. The BV group mean score was 6.3 (SD=4.3). The score between the two groups was significantly different (p<0.0001). Using a cutpoint score of 15, the sensitivity and specificity are 95.7% and 96.3% respectively indicating an excellent ability to discriminate between CI and normal BV children. In fact, these results are consistent with the original symptom survey designed as part of the Convergence Insufficiency and Reading Study (CIRS).

CONCLUSIONS. The moderate ICC value and small range for LoA indicate that the CITT-SS has good repeatability. The instrument also has the ability to differentiate CI and normal BV subject. As a result, the CITT-SS is appropriate to use as the primary outcome in a clinical trial.


Year: 2001

Program Number: 3:20 pm

Author Affiliation: The Ohio State University College of Optometry

Co-Authors: Mitchell Scheiman, Eric Borsting, Michael Rouse, Paul De Land, Marjean Taylor-Kulp, Susan Cotter, Jeffery Cooper, Richard London, CITT Study Group

Co-Author Affiliation: Pennsylvania College of Optometry, Southern California College of Optometry, Southern California College of Optometry, California State University Fullerton, The Ohio State University, Southern California College of Optometry, State University of New York, Pacific University

Room: Room 108