Improved assessment of control in intermittent exotropia using multiple measures.

Purpose: To develop and validate an improved measure of control in intermittent exotropia (XT).
Design: Prospective, noninterventional case series.
Methods: Twelve children with intermittent XT were evaluated during 4 sessions (2 hours apart) over a day, on 2 separate days (8 sessions per child). Control was standardized using a scoring system and quantified 3 times during each examination. Overall control for a day was calculated as the mean of all 12 measures. Single measures of control and the mean of 2 (double) and 3 (triple) measures over the examination were compared with the respective day mean, and first-day measures were compared to the second-day mean.
Results: At distance, 17% (49/287, 95% confidence interval [CI] 13% to 22%) of single measures differed from the day mean, whereas only 8% (16/191, 95 CI 5% to 13%) of double measures and 5% (5/95, 95% CI 2% to 12%) of triple measures differed. Comparing day 1 measures to overall mean for day 2, 17% (24/143, 95% CI 11% to 24%) of single measures and 17% (22/130, 95% CI 11% to 24%) of double measures differed by more than 1 level, whereas 11% (5/47, 95% CI 4% to 23%) of triple measures differed.
Conclusions: The mean of 3 assessments of control during a clinic examination better represents overall control than a single measure.
(Copyright © 2011 Elsevier Inc. All rights reserved.)