Improved assessment of control in intermittent exotropia using multiple measures.

Abstract

To develop and validate an improved measure of control in intermittent exotropia (XT). Prospective, noninterventional case series. 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. 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. The mean of 3 assessments of control during a clinic examination better represents overall control than a single measure.