Variability of preoperative measurements in intermittent exotropia and its effect on surgical outcome

To investigate the variability of preoperative measurements in patients with intermittent exotropia and to compare surgical outcomes according to the variability.

Patients who underwent unilateral lateral rectus recession and medial rectus resection and had 24 months' postoperative follow-up were enrolled. Patients were divided into three groups according to variability, which was defined as the largest angle minus the smallest angle ever measured during the preoperative visits; group C comprised patients with consistent exodeviation; group V_L, patients with less variability (<10^Δ); and group V_M, patients with more variability (≥10^Δ). Surgical outcomes of the three groups were compared.

A total of 344 patients were included: 128 in group C, 155 in group V_L, and 61 in group V_M. The largest variability was 20^Δ and 62.8% (216/344, group V_L + group V_M) of the patients showed variable angles of deviation during the preoperative measurements. The postoperative exodeviation increased in all groups over the 24-month follow-up; however, the postoperative exodeviation of group V_M was lower than that of both groups C and V_L (repeated-measure ANOVA, P = 0.032). There was a trend toward decreased rates of reoperation from group V_M compared with groups V_L and C (linear by linear association, P = 0.004).

More than half of patients with intermittent exotropia showed variable angles of deviation during the preoperative measurements. The surgical outcomes were better in those with variable preoperative measurements than in those with consistent preoperative measurements.