The Clinical Course of Intermittent Exotropia With Small Initial Deviation

To address the clinical course of patients who initially presented with small exodeviation (≥ 10 and ≤ 18 prism diopters [PD]) and to investigate the risk factors associated with progression.

The clinical records of patients who were first diagnosed as having intermittent exotropia of small initial deviation from August 2008 to March 2011 and were followed up for 2 or more years were reviewed retrospectively. The initial clinical features associated with the risk of disease progression and surgical intervention were analyzed.

Among 86 patients who met the inclusion criteria, 37 reached a distance deviation of 20 PD or greater and 51 underwent surgical correction for exodeviation during the follow-up. Cumulative percentages of patients whose distance deviation reached 20 PD or greater and who underwent surgery at 24 months were 47.5% and 47.7%, respectively. Mean initial stereoacuity was significantly worse in patients whose final exodeviation progressed to 20 PD or greater. The cumulative probability of surgery was significantly higher in patients who showed constant deviation at the initial examination.

Nearly half of patients with small exodeviation are expected to reach a final distance deviation of 20 PD or greater or to undergo surgery after 2 years of follow-up. Initial constant deviation was associated with increased cumulative probability of surgical intervention.