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M.T. Kulp, E. Borsting, G.L. Mitchell, M. Scheiman, S. Cotter, J. Cooper, M. Rouse, R. London, J. Wensveen, Convergence Insufficiency Treatment Trial (CITT) Study Group; Feasibility of Using Placebo VT/Orthoptics in a Multicenter Clinical Trial . Invest. Ophthalmol. Vis. Sci. 2005;46(13):5636.
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Purpose: The Convergence Insufficiency Treatment Trial (CITT) Study Group conducted a preliminary study assessing the effectiveness of home–based pencil push–up therapy and office–based vision therapy/orthoptics (VT/orthoptics) as compared to placebo VT/orthoptics for the treatment of convergence insufficiency (CI). The CITT group developed a placebo VT/orthoptics program that would provide the perception of real VT/orthoptics but did not stimulate accommodation, vergence, or involve small sequential saccadic eye movements. The purpose of this paper is to report the effectiveness of this therapy program in serving as a control. Methods: 93 subjects (ages 9 to 30 years) stratified into two groups by age and then randomized to 3 groups: push–up therapy, office–based VT/orthoptics, or office–based placebo VT/orthoptics. At the end of treatment, subjects in the two office–based VT/orthoptics groups (placebo and real) were asked: 1) which treatment do you think you received? and, 2) how sure are you about your answer? Results: 45 of 61 patients assigned to one of the VT/orthoptics groups responded to the two questions [69% (N=22 of 32) assigned to real VT/orthoptics and 79% (N=23 of 29) assigned to placebo VT/orthoptics]. Ninety–five percent (N=21/22) of the subjects assigned to real VT/orthoptics and 83% (N=19/23) assigned to placebo VT/orthoptics thought they were in the real VT/orthoptics group. Subjects assigned to placebo VT/orthoptics were no more or less likely to respond "real vision therapy" than those truly assigned to the real group (Fisher’s exact test, p=0.346). Of the patients who thought they received real VT/orthoptics, 90% assigned to real VT/orthoptics and 89% assigned to placebo VT/orthoptics were "somewhat", "pretty" or "very sure" of their answer. Those assigned to real VT/orthoptics had more responses in the "very sure" category, however. Conclusions: The CITT placebo VT/orthoptics program was effective in serving as a control in this multi–center clinical trial.
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