Postoperative changes in spatial localization following exotropia surgery

Purpose: To measure changes in spatial localization following exotropia surgery using a computer touch-screen method of measurement. Methods: Enrolled in the study were 60 exotropia patients, all of whom had undergone corrective muscle surgeries under general anesthesia: 37 patients had undergone unilateral lateral rectus or bilateral lateral rectus muscle recession procedures (recession group) and 23 patients had undergone unilateral lateral and medial rectus muscle resection (R&R), or unilateral medial rectus resection only (resection group). We evaluated spatial localization by having patients point to targets on a computer touch-screen before surgery, and 1 day and 1 month after surgery. The pointing error, Δp, is defined as the difference between the actual location of the target and the pointed-to location of the target by unsigned value, was recorded as the mean of five tests. We compared the extent of postoperative changes in Δp between the two groups. Results: The mean Δp before surgery did not differ statistically between the two groups (p = 0.93). One day after surgery, however, the postoperative change in Δp of the resection group compared with that of the recession group (2.0plusmn;.7° and 0.4plusmn;.5°, respectively) was significant (p = 0.01 and p = 0.86 respectively). Conclusions: The ability for spatial localization is decreased in patients immediately following medial rectus resection, but is regained by 1 month following surgery.