The Relationship Between Velocity of Early Exotropic Drift and Recurrence

PURPOSE: To evaluate the relationship between velocity of exotropic drift and recurrence after surgical correction of intermittent exotropia. METHODS: The medical records were retrospectively reviewed preoperatively and at the following postoperative time periods: 1 and 5 weeks and 3, 6, and 12 months. The monthly change in alignment velocity in patients who demonstrated tendencies of exotropic drift was measured. The correlation between each data point and the velocity of total period (from 1 week to 12 months) was analyzed. According to the best correlated velocity of the time period, the patients were divided into 2 groups, and the motor success rates were assessed. Each group was further divided into 3 subgroups (esotropia, orthophoria and exotropia) according to angle of deviation at 1 week, and motor success rates were assessed again. RESULTS: Exotropic drift tendency was exhibited in 113 patients (91.13%). The mean postoperative monthly change in alignment velocity of total period showed the highest correlation with 1 month (Pearson, r = 0.61). The 2 groups divided by 3.57 PD/M were not different in motor success rate. The group showing exotropia at 1 week and high exotropic drift velocity at 1 month had a low success rate (Mann-Whitney, p = 0.03). CONCLUSIONS: The velocity of exotropic drift at postoperative 1 month best reflected the total velocity but did not influence the recurrence rate. Based on the results from the present study, patients with exotropia and high exotropic drift velocity at postoperative 1 month have a greater likelihood of recurrence compared to the others.

Postoperative Exotropic Drift: Comparison of Surgical Methods Combined with Lateral Rectus Muscle Recession in Exotropia

PURPOSE: To assess the difference in the change of postoperative ocular alignment in intermittent exotropia corrected by horizontal muscle transposition or inferior oblique muscle recession together with lateral rectus muscle recession. METHODS: A total of 110 patients with intermittent exotropia with a follow-up period of more than 6 months after lateral rectus muscle recession were enrolled in the present study. The patients who received lateral rectus muscle recession only were classified as group 1, patients who received both lateral rectus muscle recession and horizontal muscle vertical transposition in both eyes were classified as group 2, and patients who underwent lateral rectus muscle and inferior oblique muscle recession were classified as group 3. The differences in postoperative ocular alignment among the patient groups were compared. RESULTS: Among the 3 groups, group 2 demonstrated the smallest amount of esotropic deviation in mean postoperative ocular alignment measured 1 day and 1 month after surgery. There was no significant difference among the groups in the mean postoperative ocular alignment and mean amount of exotropic drift at 6 months. The difference in the amount of postoperative exotropic drift 1 year after surgery among the 3 groups was statistically significant. The largest amount of postoperative exotropic drift was observed in group 1. CONCLUSIONS: In correcting intermittent exotropia, the largest amount of postoperative exotropic drift was observed in patients who received only lateral rectus muscle recession. By contrast, the smallest amount of postoperative exotropic drift was observed in patients who received lateral rectus muscle recession with vertical transposition of the horizontal muscle.

The Change in Deviation Angle with Time Course after Surgical Correction of Intermittent Exotropia

PURPOSE: To evaluate the amount and pattern of change in deviation angle with time course after surgical correction of intermittent exotropia and to evaluate the effect of pre-operative deviation and operation age on post-operative deviation change. METHODS: 54 patients who followed more than 60 months (60~120 months, mean 71.7 months) after surgical correction of intermittent exotropia were selected. We defined 'satisfactory results' that alignment of orthotropia, under 10delta esotropia and under 10delta exotropia. RESULTS: Of 54 patients, satisfactory results obtained in 96.2%(52 patients), immediate post-operation day and decreas with time course to 35.1% (19 patients) at post-operative 5 years. To quantification of change of deviation, author defined exotropic drift as +, esotropic drift as -, and no change as 0. The change of deviation between immediate post-operation and 2 years after operation is +14.55delta, between 2 years after and 5 years is +2.70delta. The change of deviation developed between immediate post-operation and 2 years after operation has statistical significance in comparison with change of deviation developed between after 2 years and 5 years after operation (P=0.0001). Pre-operative deviation has no effect on post-operative deviation change (P=0.4472) and operation age was same (P=0.3461). CONCLUSIONS: The results of surgical correction of intermittent exotropia is significantly deteriorated with time course. Exotropic drift was more pronounced between immediate post-operation and 2 years after operation and then decreased. Therefore we recommend that after surgery of intermittent exotropia patients should be followed by schedule more than 2 years and thereafter the tendency for exotropic drift will more stable. After 2 years, however, small amount exotropic drift can be possible.