A Comparison of the Maximum Deviation Measured in Intermittent Exotropia Using Various Clinical Conditions

Abstract

In the Intermittent Exotropia (IXT) population determining the largest exodeviation for surgical planning has been suggested for desired surgical outcomes (Kushner, 1998; Kim & Hwang, 2005). In this study the exodeviation of 24 IXT participants were measured at near and distance fixation, and additionally using +3.00D lenses, an increased fixation distance (20m), and after prolonged monocular occlusion (PMO), to elicit the largest exodeviation. The results of this study indicate that all near conditions increase the exodeviation. Larger deviations were observed with +3.00D lenses and +3.00D after PMO. There was no statistically significant difference between those two conditions. At distance, PMO did not produce a statistically significant increase, but 20m and 20m after PMO did. There was no statistically significant difference between the 20m conditions. This research indicates that the +3.00D lens measurement and the 20m measurement are the most clinically efficient measurements for the maximum deviation in IXT patients.