Abstract

Background/aims: To evaluate the effectiveness and dose–effect relationship of unilateral medial rectus advancement to the original insertion and lateral rectus recession in the surgical management of consecutive exotropia.

Patients/methods: The charts of 62 patients operated on for consecutive exotropia in a single-surgeon paediatric ophthalmology practice with a minimum follow-up time of 6 weeks were reviewed.

Results: Fifty-two patients were managed with unilateral surgery involving medial rectus advancement and lateral rectus recession. The medial rectus was advanced to the original insertion, and the lateral rectus was recessed by the amount of millimetres it had originally been resected for patients with precise records on previous surgery (within one millimetre of the above). The mean age at surgery for exotropia was 12.86 years. The mean postoperative follow-up time was 2.5 years. The mean preoperative distance exodeviation was 33.4 prism dioptres (PD), and the mean reduction in the angle of strabismus was 33.5 PD. A successful surgical outcome, defined as ocular alignment within 10 PD of orthophoria, was obtained in 41 patients (78.8%) at final follow-up. The mean dose–effect relationship between the reduction in the angle of deviation and the sum of millimetres of the reoperation was 2.9 PD/mm. It varied widely among patients and was strongly correlated with the amount of preoperative exodeviation, that is the patients tended to respond more per millimetre of surgical intervention the greater the preoperative exodeviation.

Conclusion: The standard reversal of unilateral medial rectus recession and lateral rectus resection is a simple and effective means for correcting secondary exotropia. The dose–effect relationship varied widely among patients and tended to correlate with the amount of preoperative exodeviation.