Postoperative Exodrift Patterns after Bilateral or Unilateral Lateral Rectus Recession in 20 Prism-diopter Intermittent Exotropia

Purpose: In the present study, the surgical outcome and postoperative exodrift pattern between bilateral lateral rectus recession (BLR) and unilateral lateral rectus recession (ULR) in intermittent exotropia of 20 prism diopters (PDs) were compared. Methods: In this retrospective study, 5.0 mm BLR or 8.5 mm ULR was performed on 82 patients for the treatment of intermittent exotropia of 20 PDs with a follow-up period of 2 years. The main outcome measures were postoperative 1-week, 1-month, 6-month, 1-year and 2-year exodeviation angles with their patterns and success rates. A surgical success was considered an alignment within 10 PDs and sensory success was defined at 100 seconds of arc. Results: The mean deviation angles at postoperative 1 week were 4.7 +/- 5.1 PD esodeviation in the BLR group (44 patients) and 1.2 +/- 4.2 PD esodeviation in the ULR group (38 patients). The BLR group was significantly more overcorrected than the ULR group (p= 0.001), but postoperative exodrift occurred in the BLR group at 1 week, 1 month, 6 months, 1 year, and 2 years. In the ULR group, the postoperative exodrift occurred at 1 week, 1 month, and 6 months which was followed by stabilized alignment. Surgical success rate at the postoperative 2-year follow-up was 75.0% in the BLR group and 81.6% in ULR group (p = 0.717). Conclusions: ULR showed less overcorrection and early exodrift up to only 6 months, resulting in stabilization of the alignment afterwards; surgical success rate at the final 2-year follow-up was similar to BLR.